58537348 GPRS EGPRS Planning Xavier

Section 1 � Module 1 � Page 1

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EVOLIUM BSS - GPRS and EGPRS Radio Network Planning


GPRS and EGPRS Radio Network Planning




Radio Network Planning - GPRS and EGPRS

All Rights Reserved © Alcatel-Lucent 2007EVOLIUM BSS - GPRS and EGPRS

Radio Network Planning

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Objectives

� By the end of the course, participants know:

� GPRS Session Management,

� TBF Management,

� Location Management,

� System Information Management,

� Cell Selection and Re-selection,

� Power Control and RLC Measurements,

� Coding Scheme and Link Adaptation,

� Radio Resources Re-allocation,

� (E)GPRS Planning Principles,

� (E)GPRS Network Planning,

� Network Evolution Scenarios,

� (E)GPRS QoS Enhancement Features,

� (E)GPRS with GSM Capacity Enhancement Features







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Objectives







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Table of Contents

Switch to notes view! Page

1 Basics 91.1 Service Overview GPRS 101.2 Service Overview EGPRS 111.3 Support of GPRS QoS classes 121.3.1 Radio Network Planning Impact 13

1.4 Dual Transfer Mode 141.4.1 Radio Network Planning Impact 15

1.5 (E)GPRS MS Multislot Classes 161.6 (E)GPRS General Architecture 171.7 Alcatel (E)GPRS Architecture 191.8 (E)GPRS Protocol Layers (Transmission Plane) 221.9 Alcatel (E)GPRS BSS Hardware support 231.10 Modulation Technique: 8-PSK only for EGPRS 241.11 8-PSK TRA Power Aspects 251.12 (E)GPRS Radio Blocks Structure 291.13 GPRS Channel Coding 311.14 EGPRS Channel Coding 341.15 Radio Link Adaptation Overview 391.16 Automatic ReQuest for repetition (ARQ) 401.17 Type-I ARQ mechanism 411.18 Type-I ARQ in GPRS 421.19 Type-I ARQ in EGPRS 431.20 (E)GPRS radio physical channel: PDCH Concept 471.21 (E)GPRS Multiframe 481.22 (E)GPRS Logical Channels 491.23 Master/Slave PDCH concept 511.24 Temporary Block Flow 521.25 Resources Sharing 541.26 MS multiplexing co-ordination 581.27 GPRS mobility management (GMM) states for MS 611.28 Radio Resource (RR) operating modes for MS 621.29 Attach procedure 631.30 PDP context activation 651.31 Location management 661.32 Routing Area 671.33 Network Mode of Operation (NMO) 681.34 TBF establishment 691.35 UL TBF establishment on CCCH, 1 phase access 701.36 UL TBF establishment on CCCH, 2 phases access 721.37 DL TBF establishment on CCCH 741.38 System information broadcasting on BCCH 751.39 System information broadcasting on PBCCH 771.40 (E)GPRS Transmission Aspects 801.40 TRX Classes Concept 811.41 Two Abis Links per BTS 84

2 B9 features 852.1 Enhanced Packet Cell Reselection (R4 MSs) 862.1.1 Radio Network Impact 87

2.2 Extended Uplink TBF Mode 882.2 Radio Network Planning Impact 892.3 Enhanced support of E-GPRS (EDGE) in uplink 912.3.1 Radio Network Planning Impact 93

2.4 Counter Improvements for Release B9 942.4.1 Radio Network Planning Impact 98

2.5 Autonomous Packet Resource Allocation 99







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Table of Contents [cont.]


2.5.1 Radio Network Planning Impact 1012.6 2G/3G Inter-working 1022.6.1 Radio Network Planning Impact 105

2.7 M-EGCH Statistical Multiplexing 1062.7.1 Radio Network Planning Impact 108

2.8 Dynamic Abis allocation 1092.8.1 Radio Network Planning Impact 110

2.9 Enhanced transmission resource management 1112.10 RMS_I1 Improvements 1122.10.1 Radio Network Planning Impact 113

2.11 RMS_I2 Improvements 1142.11.1 Radio Network Planning Impact 115

3 (E)GPRS Radio Algorithms 1163.1 Cell Reselection Overview 1173.2 Cell reselection: NC0 mode, no PBCCH established 1213.3 Cell reselection: NC0 mode, PBCCH established 1233.4 Cell reselection execution: NC0 in PTM 1303.5 Cell reselection: NC2 mode 1323.6 GPRS redirection 1433.7 GPRS Power Control: Overview 1453.8 GPRS Power Control: Measurements 1463.9 GPRS Power Control: Algorithm 1503.10 Link adaptation: DL GPRS Radio Link Control 1533.11 Link adaptation: UL GPRS Radio Link Control 1573.12 Link adaptation in EGPRS: New metrics 1603.13 Link adaptation: DL EGPRS Radio Link Control 1613.14 EGPRS Link Adaptation Decision 1633.15 TRX ranking/TRX transmission pool set-up 1643.16 TRX capability for PS traffic 1663.17 Radio Resource Allocation: Overview 1673.18 Radio Resource Allocation: PDCH state 1683.19 TRX selection for EGPRS TBFs 1713.20 Radio Resource Allocation: EGPRS TBFs 1763.21 Radio Resource Allocation: TBF Re-allocation 1793.22 Radio Resource Allocation: Min_PDCH 1803.23 Radio Resource Allocation: Fast initial (E)GPRS access 181

4 General (E)GPRS planning principels 1824.1 Throughput Dependency -> Interference (and Level) 1834.2 Packet data throughput 1844.3 Reference performance point 1854.4 Saturation effect 1864.5 Cell area and throughput 1884.6 Throughput <-> C/I 189

5 (E)GPRS Network intoduction 1915.1 GPRS network planning 1925.2 GPRS Greenfield planning 1935.3 GPRS traffic calculation and traffic analysis 1955.4 GPRS traffic calculationand PS traffic 1965.5 GPRS traffic calculation and user profile 1985.6 GPRS traffic calculation and market applications 1995.7 GPRS traffic calculation and user behavior 2005.8 Customer questionnaire 2015.9 Traffic Model (Example) 2035.10 User mapping 2045.11 Multi-Service 205







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Table of Contents [cont.]


5.12 QoS per User Application 2065.13 GPRS traffic calculation 2075.14 Exemplary results of the 3 traffic calculation methods 2125.15 GPRS traffic calculation result 217

6 (E)GPRS Network design 2186.1 General 2196.2 Frequency planning 2226.3 Throughput 2246.4 Link budget 2256.5 Interference analysis on BCCH frequencies 2286.6 Interference analysis on TCH frequencies 2296.7 TRX assignment to GPRS service 2306.8 GPRS Analysis 2316.9 LA and RA planning 2356.10 Quality of Service 245

7 Considerabele features to react (E)GPRS target 2487.1 General 2497.1 Optimization campaign on parameters 2507.2 MPDCH 2517.3 Enhanced PDCH Adaptation & Fast pre-emption 2547.4 User multiplexing 2557.5 PDCH Resource Multiplexing 2567.6 Radio (TBF) Resource Reallocation 2577.7 Coding Scheme Adaptation 2597.8 Cell Reselection 2607.8 GPRS Power Control 2627.8 Features on DL TBF establishment and release 2637.8.1 Delayed DL TBF release 2647.8.2 Fast Downlink TBF re-establishment process 2667.8.3 Non-DRX feature 267

8 GPRS introduction into oerational GSM network 2688.1 General 269

9 GSM Network enhancement features & GPRS 2759.1 Frequency Hopping 2769.2 µ-cell 2789.3 Dual Band 2809.4 Concentric cell 283

10 E-GPRS 28410.1 E-GPRS main differences 285

11 GPRS traffic calculation example 28811.1 Customer questionnaire (Example) 28911.2 User and area distribution determination 29111.3 Traffic demand for CS traffic 29211.4 Traffic demand for packet traffic 29311.5 Network capacity calculation 29711.6 Traffic dimensioning 301







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1 Basics







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1 Basics

1.1 Service Overview GPRS

� GPRS “General Packet Radio Service”

� GPRS is a GSM feature

� It has been introduced to provide end-to-end packet-switched (PS) data transmission between MS users and fixed packet data networks

� GPRS provides efficient utilization of the radio resources:

� multislot operation

� flexible sharing of radio resources between MS

� resources are allocated only when data are transmitted

� Charging is mainly based on data volume transmitted and not on the connection time







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1 Basics

1.2 Service Overview EGPRS

� EDGE “Enhanced Data rates for GSM Evolution”

� ETSI standardized solution and can be introduced in two ways:

� CS enhancement: Enhanced circuit-switched data or ECSD

� PS enhancement for GPRS � EGPRS

� EGPRS relies on the introduction of 8-PSK (Eight Phase Shift Keying)modulation technique:

� Same qualities in terms of generating interference on an adjacent channel as GMSK � makes possible to integrate EDGE channels into existing frequency plan

� 8-PSK Symbol rate = GMSK Symbol rate, but one symbol represents now 3 bits instead of 1 bit in GMSK � increased data rates







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1 Basics

1.3 Support of GPRS QoS classes

� Four QoS classes (or traffic classes) are defined:

� The conversational class will be very likely dedicated to real-time conversation. Speech and video conferencing tools are some examples of such applications

� The streaming class corresponds to a real-time stream and enforces mainly constraints on jitter. Video streaming or PoC (Push to takover Celullar) are typical applications for the streaming traffic class.

� The interactive class corresponds to mainly to traditional Internet applications like web browsing. Some differentiation can be donebetween two services by using the traffic handling priority attribute.

� The background class is typically corresponding to Best Effort services. Applications that make use of this class might be e-mail downloading, SMS, or even ftp downloading.

� PFC procedure

• Packet Flow Context (PFC) is a concept introduced starting with R99 3GPP release to ensure that the

BSS is involved in the R99 QoS negotiation. The interest of PFC is to differentiate on the radio

interface the conversational and streaming traffics and to reserve resources for these traffics.

Without the PFC, the BSS only knows the R97/98 QoS parameters (correspond to the interactive and

background R99 QoS classes). It enables to perform admission control and QoS based resource

allocation in the BSS.

• R99 QoS is taken into account if the PFC (Packet Flow Context) procedures are supported by the MS,

the BSS and the SGSN. It allows the BSS B9 to handle streaming and interactive traffics and also to

negotiate the QoS parameters.

• R97/98 QoS should be also taken into account (OP12) if PFC is not supported by the MS or the SGSN in

order to handle interactive traffics or some specific applications as PoC (Push over Cellular).







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1 Basics

1.3.1 Radio Network Planning Impact

� QoS subfeatures are of great interest in traffic-driven networks (number of sites determined by the traffic to be carried, not by the coverage per site). They will define the actual traffic shape in the cell by allocating, in a selective manner, resources for (CS and) PS calls. Here a traffic capacity gain is expected (higher traffic levels can be handled with feature activated than without).

� Radio interface impact

• a) Support of PFC feature by RLC/MAC :

- PFC_FEATURE_MODE: this 1 bit field is a part of the R99 extensions in the GPRS_Cell_Options. It is

broadcasted on BCCH (SI13) or PBCCH (PSI1, PSI13 and PSI14) and indicates to the MSs if the network supports

the PFC feature.

- The PFC impact on the one phase access: "If the PFC_FEATURE_MODE is set in the system information and if a

PFC exists for the LLC data to be transferred then the PFI shall be transmitted along with the TLLI of the

mobile station in the RLC extended header during contention resolution. The PFI is not used for contention

resolution but is included to indicate to the network which PFC shall initially be associated with the uplink

TBF.„

• b) RLC/MAC/… messages impacts:

- PI bit (PFI indicator) is created, it indicates the presence of the optional PFI field:

› 0 PFI is not present

› 1 PFI is present if TI field indicates presence of TLLI

› The PFI field indicates a PFI coded as it is defined in TS 44.018.

� RLC/MAC messages impacted are:

• Packet Resource Request : PFI field is added

• (EGPRS) Packet DL ACK/NACK: PFI field is added (if a Channel Request Description is also present)

• UL (EGPRS) RLC data blocks : PFI field is added after the TLLI field (see 44.060 § 10.2.2 and 10.3a.2).

� PFI is included in the following SM messages :

• Activate_PDP_Context_Accept,

• Activate_Secundary_PDP_Context_Accept,

• Modify_PDP_Context_Request (sent by the network) and

• Modify_PDP_Context_Accept (in case the request to modify is sent by the MS).

� PFC_FEATURE_MODE is included in the MS_Network_Capability I.E. (which is sent in the Attach_Request and

RA_Update_Request GMM messages).







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1 Basics

1.4 Dual Transfer Mode

� This feature allows a dual transfer mode capable MS to use a radio resource for CS traffic and simultaneously one or several radio resources for PS traffic.

� Single slot operation DTM MSs are not supported in Alcatel BSS because the implementation of these MSs is difficult compared to the throughput expected in PS services. Only multislot operation DTM MSs are supported.

� In Alcatel’s implementation, the Gs interface is required to support DTM to ensure CS paging co-ordination. It avoids the BSS to ensure the paging co-ordination.

� While in dual transfer mode, the BSS only allocates full rate PDCH to the MS.

� The dynamic Abis feature allows to simplify the radio resource allocations. It avoids defining new TBF re-allocation triggers.

!!!!! B10 FEATURE ONLY !!!!







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1 Basics


� Some restrictions towards BSS in deploying DTM exist. They are presented below: � Half rate

� Support of half rate configurations (one single timeslot encompassing one half rate circuit channel + one half rate packet channel) was not considered in the first implementation of DTM.

� Inter-cell handovers� The number of inter-cell handovers should be minimized for DTM calls, as an inter-cell HO leads to the re-allocation of the packet session. Therefore, handover causes having a low priority should be inhibited for the time the MS is operating in DTM.

� Intra-cell handovers� The number of intra-cell handovers should be minimized for DTM calls, as an intra-cell HO leads to the re-allocation of the packet session.

� Hierarchical networks� As (E)GPRS are preferentially offered in macro cells, the BSS shall ensure that at least one PDCH can be used in micro cells to re-direct the MS towards the macro cells. It means that the BSS shall allow a PDCH used by a MS operating in DTM mode to be shared by other (E)GPRS MS.

!!!!! B10 FEATURE ONLY !!!!







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1 Basic

1.5 (E)GPRS MS Multislot Classes

Multislot

Class1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

RX Timeslots 1 2 2 3 2 3 3 4 3 4 4 4 3 4 5 6 7 8 6 6 6 6 6 8 8 8 8 8 8

TX Timeslots 1 1 2 1 2 2 3 1 2 2 3 4 3 4 5 6 7 8 2 3 4 4 6 2 3 4 4 6 8

Sum of

Timeslots2 3 4 4 4 4 4 5 5 5 5 5 n.a.n.a.n.a.n.a.n.a.n.a.n.a.n.a.n.a.n.a.n.a.n.a.n.a.n.a.n.a.n.a.n.a.

� EGPRS MS is characterized by two multislot classes:� GPRS multislot class

� EGPRS multislot class

� Typically, EGPRS multislot class < GPRS multislot class E.g. the multislot class of the mobile can be 3 RXs + 2 TXs (class 6) in pure GPRS mode and 2 RXs + 1 TX (class 2) in pure EGPRS mode

� Type 1: class 1-12, class 19-29 recognized as class 10

� Type 2: class 13-18, allocation is limited to max. 5+5 timeslots

� MS type

• Type 1 are simplex MSs, i.e., without duplexer: they are not able to transmit and receive at the same time

• Type 2 are duplex MSs, i.e., with duplexer: they are able to transmit and receive at the same time

� Rx

• The maximum number of received time slots that the MS can use per TDMA frame. The receive TS shall be

allocated within window of size Rx, but they do not need to be contiguous. For SIMPLEX MS, no transmitted

TSs shall occur between receive TS within a TDMA frame. This does not take into account the measurement

window (Mx).

� Tx

• The maximum number of transmitted time slots that the MS can use per TDMA frame. The transmitted TS

shall be allocated within the window of size Tx, but they do not need to be contiguous. For SIMPLEX MS, no

received TS shall occur between transmit TS within a TDMA frame.

� SUM

• The maximum number of transmitted and received time slots (without Mx) per TDMA frame.

� The meaning of Ttb, Tra et Trb changes regarding MS types.

• For SIMPLEX MS (type 1):

- Ttb is the minimum time (in time slot) necessary between the Rx and Tx windows.

- Tra is the minimum time between the last Tx window and the first Rx window of the next TDMA in

order to be able to open a measurement window.

- Trb is the same as Tra without opening a measurement window.

• For DUPLEX MS (type 2):

- Ttb is the minimum time necessary between 2 Tx windows belonging to different frames.

- Tra is the minimum time necessary between 2 Rx windows belonging to different frames in order to be

able to open a measurement window.

- Trb is the same as Tra without opening a measurement window.







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1 Basics

1.6 (E)GPRS General Architecture

� (E)GPRS defines a network architecture dedicated to packet service domain, with radio access, which allows service subscriber to send and receive data in an end-to-end packet transfer mode

� (E)GPRS uses the BSS architecture, but defines a fixed network (GPRS backbone) which is different from the NSS, and which links the BSS to PDNs (packet data networks). The BSS is used for both circuit-switched and (E)GPRS services

� The BSS has 2 clients:

� the MSC, for circuit-switched services (A interface)

� the GPRS backbone network, for GPRS (Gb interface)

� one or more 64 kbit/s channels on one or more 2 Mbit/s links

� Gb interface: Layer 1 specified in GSM 08.14The protocol stack defined in the stage 2, GSM 03.60







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1 Basics

1.6 (E)GPRS General Architecture [cont.]

� (E)GPRS general architecture

GbInterface

PDNGPRS

backbone

Gi

Packet Switched services domain

BSS

MSC/VLR PSTN

Circuit Switched services domain

A

Interface

� GPRS network = IP network

• Note: Additional IP routers might be used to route the information between the GSNs (intra-PLMN

backbone network). All the elements connected to this backbone have private permanent IP

addresses.

� Signaling protocols:

• MAP/TCAP/SCCP/MTP on Gr, Gd and Gc (through the SGSN for the latter),

• GTP/UDP/IP on Gn, BSSAP+/SCCP/MTP on Gs,

• GMM/SM/LLC on Gb/Um.

� Gc: for Network-Requested PDP contexts Activation (the GGSN asks the HLR for SGSN Routing

Information).

� Gs: defines the Network Mode of Operation I. It allows to perform LA + RA combined Location Update,

and PS and CS Paging Coordination.

� Gr: exchange of Subscription Information at Attachment Phase.

� Additional interfaces:

• Gf (to the EIR).

• Gd to deliver the SMS to the mobiles via the GPRS network (SGSN option and subscriber feature).







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1 Basics

1.7 Alcatel (E)GPRS Architecture

� Packet Control Unit (PCU) function is defined by the GSM standard:� controls the (E)GPRS activity in a cell

� handles RLC/MAC functions

� may be either implemented in the BTS, BSC or the SGSN

� Alcatel choice:� PCU implemented in a new network element, A 9135 MFS (Multi-BSS Fast Packet Server)

� smooth and cost effective introduction of the GPRS

� The standard specifies that the PCU function shall be implemented in one of the 3 following entities:

• BTS,

• BSC,

• after the BSC (in the SGSN for instance)

� The implementation of the PCU functions determines the position of the Gb interface. ALCATEL chose

the MFS integration in order to offer a faster implementation inside the BSS as well as an easier

maintenance and supervision.

� MFS: Multi BSS Fast packet Server.







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1 Basics

1.7 Alcatel (E)GPRS Architecture [cont.]

� Alcatel packet-switched service domain architecture:

BTS

Internet/

Intranet

SGSN GGSNMFSBSCFire-

wall

Other

PLMN

Packet domain

GnGbAterAbis

MS

Gi

Gp







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1 Basics

1.7 Alcatel (E)GPRS Architecture [cont.]

� GPRS backbone is an IP network and is composed of routers:

� Serving GPRS Support Node (SGSN), at the same hierarchical level as the MSC, which is linked to several BSSs. It keeps track of the individual MS’s location and performs security functions and access control

� Gateway GPRS Support Node (GGSN), which is linked to one or several data networks, provides interworking with external packet-switched networks and is connected with SGSNs via an IP-based GPRS backbone network







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1 Basics

1.8 (E)GPRS Protocol Layers (Transmission Plane)

NSNetwork Service

GSM 08.16

RLCRadio Link Control

GSM 04.60

httpHypertext Transfer

Protocol

relay

MACMedium Access

Control

GSM 04.60

LLCLogical Link Control

GSM 04.64

Physical

Link LayerL1bisLayer 1bis

GSM 08.14

Um Abis / AterMS MFSBTS Gb SGSN

L1-GCHLayer 1 GPRS

Channel

L2-GCHLayer 2 GPRS

Channel

BSSGP

BSS GPRS Protocol

GSM 08.18

UDPUser Datagram

ProtocolRFC 768

TCPTransmission Control

ProtocolRFC 793

or:

IPInternet Protocol

RFC 791

GTPGPRS Tunneling

Protocol

GSM 09.60

Gn GGSN

SNDCPSubnetwork

Dependent

Convergence

Protocol

GSM 04.65

Ethernet

FRFrame Relay

ATMAsynchronous

Transfer Mode

E1 (PCM30)G.703 / G.704

Gi

relay

relay


Protocol

RFC 793

RLCRadio Link Control

GSM 04.60

MACMedium Access

Control

GSM 04.60

L1-GCHLayer 1 GPRS

Channel

L2-GCHLayer 2 GPRS

Channel

NSNetwork Service

GSM 08.16

BSSGP

BSS GPRS Protocol

GSM 08.18

LLCLogical Link Control

GSM 04.64

SNDCPSubnetwork

Dependent

Convergence

Protocol

GSM 04.65

IPInternet Protocol

RFC 791

GTPGPRS Tunneling

Protocol

GSM 09.60

IPInternet Protocol

RFC 791

and/or:

or:

UDPUser Datagram

ProtocolRFC 768


ProtocolRFC 793

or:

Ethernet

FRFrame Relay

ATMAsynchronous

Transfer Mode

E1 (PCM30)G.703 / G.704

IPInternet Protocol

RFC 791

and/or:

or:

Application example

wwwWorld Wide Web

Physical

RF Layer

Physical

Link Layer

Physical

RF Layer

L1bisLayer 1bis

GSM 08.14

� For the exact purposes of the tracing, please refer to “Introduction to GPRS & E-GPRS Quality of

Service Monitoring” It can be said from this protocol stacks diagram that after allocation of a GCH by

the BSC to the MFS, the data carried over the GCH are transparent for the BSC.

� The RLC function defines the procedures for segmentation and reassemble of LLC PDUs into RLC/MAC

blocks and, in RLC acknowledged mode of operation, for the Backward Error Correction (BEC)

procedures enabling the selective retransmission of unsuccessfully delivered RLC/MAC blocks. In RLC

acknowledged mode of operation, the RLC function preserves the order of higher layer PDUs provided

to it. The RLC function provides also link adaptation. In EGPRS in RLC acknowledged mode of

operation, the RLC function may provide Incremental Redundancy (IR).

� The MAC function defines the procedures that enable multiple mobile stations to share a common

transmission medium, which may consist of several physical channels. The function may allow a

mobile station to use several physical channels in parallel, i.e., use several time slots within the TDMA

frame. For the mobile station originating access, the MAC function provides the procedures, including

the contention resolution procedures, for the arbitration between multiple mobile stations

simultaneously attempting to access the shared transmission medium. For the mobile station

terminating access, the MAC function provides the procedures for queuing and scheduling of access

attempts.







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1 Basics

1.9 Alcatel (E)GPRS BSS Hardware support

� BTS: Support of EGPRS (EDGE) in all BTS A9100 EVOLIUM™ Evolution equipped with TRA transceiver:

� G1 MK2 and G2 with DRFU: GPRS only, CS-1 and CS-2 only

� A9100 EVOLIUM (G3): GPRS only, CS 1-4

� A9100 EVOLIUM Evolution (G4): (E)GPRS, CS 1-4, MCS 1-9

� micro BTS: support of EDGE in micro BTS A9110-E� Micro BTS A9110 (M4M): GPRS only, CS 1-4

� Micro A9110-E (M5M): (E)GPRS, CS 1-4, MCS 1-9

� BSC A9120 (G2)

� MFS A9135

� TC A9125 (Transcoder)� G2 and G2.5







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1 Basics

1.10 Modulation Technique: 8-PSK only for EGPRS

Q

I

010

011

100

101

111

110

001

000

Q

I

111

110

001

000100

101

010

011

I

Q110

100

000

010

101

001

011

111

t

Q

I

010

011

100

101

111

110

001

000

Q

I

010

011

100

101

111

110

001

000

Q

I

111

110

001

000100

101

010

011

Q

I

111

110

001

000100

101

010

011

I

Q110

100

000

010

101

001

011

111

I

Q110

100

000

010

101

001

011

111

t

Q

I

Q

IdB

(147 bits)

PN

0

-20

� 8-PSK = Phase Shift Keying� 8-PSK is not a constant envelope modulation. Part of the information

is conveyed by the amplitude of the carrier which varies over time

� An 8PSK signal carries three bits per modulated symbol over the radio path which allows to tripled the data transmission rates

� GMSK = the Gaussian Minimum Shift Keying belongs to a subset of phase modulations

� 8-PSK = 8-state Phase Shift Keying

• 8-PSK is not a constant envelope modulation. Part of the information is conveyed by the amplitude of the carrier which varies over time.

• An 8-PSK signal carries three bits per modulated symbol over the radio path, which allows to triple the data transmission rates.

� Modulation gross bit rate

• The normal burst is divided into 156.35 symbol periods. A normal burst has a duration of 3/5.2 seconds (577 µs). (3GPP TS 05.02).

• For GMSK modulation, a symbol is equivalent to a bit (3GPP TS 05.04)

• A GMSK burst is composed of 156.35 bits (6 tail bits + 26 training sequence bits + 116 encrypted bits + 8.25 guard period (bits))

• Modulation gross bit rate = (156.35 bits) / (3/5.2 seconds) = 270 Kbit/s

� For 8-PSK modulation, one symbol corresponds to three bits (3GPP TS 05.04).

• An 8-PSK burst is composed of 156.35 x 3 = 468.75 bits (18 tail bits + 78 training sequence bits + 348 encrypted bits + 24.75 guard period (bits)).

• Modulation gross bit rate = (468.75 bits) / (3/5.2 seconds) = 810 Kbit/s

Amplitude variesconstantCarrier envelope

EGPRSGPRS / EGPRSPacket radio service

810 Kbit/s270 Kbit/sGross bit rate per

carrier

200 KHz200 KHzChannel spacing

Phase modulationFrequency modulationModulation type

8-PSKGMSK







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1 Basics

1.11 8-PSK TRA Power Aspects

25 W / 44 dBm60 W / 47.8 dBm1800 HP

30 W / 44.8 dBm45 W / 46.5 dBm900 EDGE+

30W / 44.8 dBm35 W / 45.4 dBm1800 EDGE+

12 W / 40.8 dBm35 W / 45.4 dBm1800 MP

25 W / 44 dBm60 W / 47.8 dBm900 HP

15 W / 41.8 dBm45 W / 46.5 dBm900 MP

8-PSK output powerGMSK output powerTRA

� Nominal output power (PN) of the transmitter represents the average power during the active burst

� GMSK average power is identical to GMSK peak power

� 8-PSK peak power is equal to GMSK peak power but the 8-PSK average power is lower than the peak power

� 8-PSK power < GMSK power

� the difference is called average power decrease (APD) or power back off

� G3 TREs are not able to handle the 8-PSK modulation. Only G4 TREs (also called TRA) are EDGE capable.

� The TRA sensitivity is as follows :

• GMSK : - 111 dBm.

• 8-PSK : - 108 dBm for MCS5, - 99 dBm for MCS9.







1 � 1 � 26

1 Basics

1.11 8-PSK TRA Power Aspects [cont.]

� Unbalanced BTS configuration

� Case 1: BS_TXPWR_MAX=0

� Case 2: BS_TXPWR_MAX<>0

� APD, takes into account the BS_TXPWR_MAX and consequently the Effective GMSK Sector Power

� Always 8 PSK pwr ≤ GMSK pwr

� APD = 0 if 8 PSK pwr > GMSK pwr

� Used by Link Adaptation process

� 8-PSK Delta power (∆ 8-PSK) considers only the GMSK sector power without the BS_TXPWR_MAX

� 8-PSK ∆ ≤ 3 dB indicates that is a high power TRE

GMSK POWER

8-PSK POWER

ATTENUATION

BS_TXPWR_MAX

∆ 8-PSK

APD

GMSK LEVELING

LEGEND

OUTPUT PWR

@ BTS ant.

connector

SECTOR GMSK

8-PSK TRE 1

8-PSK TRE 2

HP TRE 1 MP TRE 1 HP TRE 1 MP TRE 2

∆-8PSK= APD

∆-8PSK= APD APD = 0

Case 1 Case 2

� APD: Average Power Decrease

• The back-off between average GMSK and 8-PSK output power comes from physics since 8-PSK is a non

constant envelope modulation unlike GMSK.

• As a consequence power amplifiers can not be used at their maximum power. This results in a

difference between mean output powers for GMSK and 8-PSK modulations.

� Output power handling

• The BTS sets all the TRE which transmit GMSK output powers at the same level which is the minimum

value among the maximum TRE output power in a sector and in a given band.

• On a TRE, the maximum GMSK output power is higher than the maximum 8-PSK output power.

• An O&M parameter (BS_TXPWR_MAX) allows a static power reduction of the maximum GMSK output

power of the sector.

• The TRE transmit power in 8-PSK shall not exceed the GMSK transmit power in the sector.

• The BTS determines for each TRE, the difference between the 8-PSK output power of the TRE and the

GMSK output power of the sector (8-PSK delta power).

• According to the 8-PSK delta power value, a TRE is called “High Power” or “Medium Power”.

• When a GCH channel is activated, the BTS sends the 8-PSK delta power to the MFS.

Together with BS_TXPWR_MAX (static power reduction), the 8-PSK delta power allows the MFS to

determine:

- a possible attenuation (BS_TX_PWR) for the 8-PSK DL RLC block emission, in order not to exceed

the GMSK power of the sector (for GMSK DL RLC block, the attenuation is BS_TXPWR_MAX).

- an Average Power Decrease which is the difference between the 8-PSK output power and the GMSK

output power after having taken into account BS_TXPWR_MAX. The Average Power Decrease is taken into account in the link adaptation tables.







1 � 1 � 27

1 Basics


� Example:� GSM 900, a mix BTS sector configuration is considered:

� ANc combined with 4 TRA (TRAs = EGPRS capable TRE):

� TRE 1 (BCCH): 60W GMSK (25W in 8-PSK)

� TRE 2..4: 45W GMSK (15W in 8-PSK)

� BS_TXPWR_MAX = 2 dB;

� RESULTS:

� 1st step: Output power at BTS antenna connector (after combiner and duplexer stage):

� TRE 1 GMSK = 43.4 dBm; 8-PSK = 39.6 dBm

� TRE 2..4 GMSK = 42.1 dBm; 8-PSK = 37.4 dBm

� 2nd step: LEVELING (BTS automatic GMSK power balancing):

� TRE 1..4 GMSK = 42.1 dBm (Sector GMSK power)







1 � 1 � 28

1 Basics


� 3rd step: 8-PSK Delta computation

� ∆ TRE 1 = 42.1 – 39.6 = 2.5 dB < 3 dB � recognized as HP TRE

� ∆ TRE 2..4 = 42.1 – 37.4 = 4.7 dBm � recognized as MP TREs

� 4th step: static attenuation (only on GMSK power)

� TRE 1..4 GMSK = 42.1 – 2 = 40.1 dBm (Effective GMSK Sector Power)

� 5th step: GMSK power ≥ 8-PSK power ?� YES, since 40.1 dBm ≥ 39.6 dBm ≥ 37.4 dBm � no reduction of 8-PSK power

� 6th step: APD computation

� APD TRE 1 (BCCH) = 40.1 – 39.6 = 0.5 dB

� APD TRE 2..4 = 40.1 – 37.4 = 2.7 dB

3GPP 05.08 constraint on the transmitted power of BCCH frequency:

BCCH frequency shall usually be transmitted at a constant level. A tolerance has been introduced with 8-PSK: a fluctuation of up to 2 dB is allowed

�� If APD is greater than 2 dB, a static power attenuation should be applied or EGPRScapability should not be activated on the BCCH TRE

� Radio Network Planning Impact

• Frequency hopping is not recommended for E-GPRS (MCS-1 to MCS-9)

• Therefore, the system is allocating a higher priority for the packet-switched traffic for non-hopping

TRX in a cell.

• In addition, the non-hopping TRX may benefit from a special radio planning with higher reuse cluster

size, in order to ensure higher C/I conditions and offer better throughputs, both for GPRS and EDGE.

APD should be considered in the A9155 planning tool for the throughput estimation (based on

interference calculation per pixel approach) and also to determine the 8-PSK coverage.

• The IR gain should also be considered in the throughput estimation. 3 dB can be taken for the average

IR gain.

• PS_PREF_BCCH_TRX is a flag at cell level which indicates whether the operator wishes to allocate

packet on the BCCH TRX with highest priority. Actually, is recommended to activate GPRS/EDGE

traffic on the BCCH TRX due to its high RCS. However the activation of EDGE on the BCCH TRX should

be performed cautiously.

• 3GPP Rec. 05.08 has defined a constraint on the transmitted power of BCCH frequency. This

frequency shall usually be transmitted at a constant level. A tolerance has been introduced with 8-

PSK: a fluctuation of up to 2 dB is allowed. Depending on the configuration in the BTS, it may happen

that the difference between GMSK and 8-PSK power on the BCCH TRX is greater than 2dB. A possible

solution for this constraint, in case of a BTS (e.g. ANc combined) equipped only with MP TRX (most of

the cases) is presented below: The BCCH MP TRX will be replaced by a HP TRX (to take also

advantage from 8-PSK 25W power and ∆<3dB) BS_TXPWR_MAX will be set to 2 dB The difference

between GMSK and 8-PSK power on BCCH TRX will be: (42.1 – 2) – 39.6 = 0.5 dB which respects the

ETSI constraint. The drawback is that CS and GPRS service may be affected by the GMSK output

power reduction.







1 � 1 � 29

1 Basics

1.12 (E)GPRS Radio Blocks Structure

� In order to be transmitted over the air interface, the LLC data is segmented at RLC layer into packets, called (E)GPRS radio blocks

� Radio block characteristics:

� a block is the smallest data unit assigned to an user

� one radio block is always entirely assigned to one user; inside a block there is no multiplexing of different users possible

� the whole information belonging to one radio block is transmitted upon channel coding, in a certain timeslot over 4 consecutive TDMA frames

� the data amount carried in one (E)GPRS radio block is: � 456 bits in GPRS (GMSK modulation)

� 464 bits in EGPRS (GMSK modulation)

� 1392 bits in EGPRS (8-PSK modulation)







1 � 1 � 30

� EGPRS Radio Block (data transfer)

� RLC/MAC header: control fields which are different for uplink and downlink directions

� RLC Data Field: LLC PDUs bytes; contains one or two RLC data blocks� Block Check Sequence (BCS): for error detection of the data part

� Header Check Sequence (HCS): for error detection of the header part

1 Basics

1.12 (E)GPRS Radio Blocks Structure [cont.]

� GPRS Radio Block (data transfer)

� MAC header: control fields which are different for uplink and downlink directions

� RLC header: control fields which are different for uplink and downlink directions

� RLC Data Block: bytes from one or more LLC PDUs

� Block Check Sequence (BCS): used for error detection

MAC header RLC data blockRLC header BCS

BCSHCSRLC/MAC header RLC data block 1 RLC data block 2only MCS-7/8/9







1 � 1 � 31

1 Basics

1.13 GPRS Channel Coding

� Channel coding provides error detection and error correction

� Essential for managing the impairments on the air interface

� Data rates in GPRS on the air interface

� The useful data rates on the air interface depend on the channel coding procedure

� For (E)GPRS, different channel coding levels are applied depending on the actual radio conditions







1 � 1 � 32

1 Basics

1.13 GPRS Channel Coding [cont.]

� Four different coding schemes, CS-1 to CS-4, are defined for the GPRS Radio Blocks carrying RLC data, and are applied depending from the actual radio conditions

� The first step of the channel coding procedure is to add a BlockCheck Sequence (BCS) for error detection

� For CS-1 to CS-3, the second step consists of pre-coding USF (except for CS-1), adding four tail bits and a half rate convolutional coding for error correction that is punctured to give the desired coding rate

� For CS-4 there is no coding for error correction

� The most protected mode is CS-1 which is therefore always used for GPRS signaling (even for EGPRS)







1 � 1 � 33

1 Basics

1.13 GPRS Channel Coding [cont.]

8.00.50Half rate convolutional

coding

GMSKCS-1


coding, punctured

GMSKCS-2


coding, punctured

GMSKCS-3

20.01.00No codingGMSKCS-4

Maximum data rate

per TS (RLC payload)[kbps]

Code

rate

Coding schemes

for RLC data block

Modulation

schemes

Scheme

8

12

14.4

CS-1

CS-2

CS-3

CS-420

GMSK modulation

Header + Protection

Maximum User Payload [kbps]

USF BCS

rate 1/2 convolutional coding

456 bits

puncturing

Interleaving of GPRS Radio Block over 4 consecutive TDMAs (4 PDCH)

GPRS RADIO BLOCK

Release B8







1 � 1 � 34

1 Basics

1.14 EGPRS Channel Coding

� Nine different coding schemes are defined: MCS-1 to MCS-9

� First step of the EGPRS coding procedure, is to add a Block Check Sequence (BCS) to each RLC data block, for error detection

� Second step consists of adding six tail bits (TB) and a 1/3 rate convolutional coding for error correction that is punctured to give the desired coding rate

� The Pi (puncturing schemes) for each MCS correspond to differentpuncturing schemes achieving the same coding rate

� Puncturing is a technique of removing bits in predetermined locations of the data block after the block has been channel coded

� MCS-9, MCS-8, MCS-7, MCS-4, MCS-3: are possible P1, P2, and P3

� MCS-6, MCS-5, MCS-2, MCS-1: P1 and P2 are possible

The puncturing process consists of transmitting only some of the coded bits obtained after the rate 1/3

convolutional coding. Depending on the considered puncturing scheme, different coded bits are transmitted.

Therefore, when the receiver receives two versions of the same RLC block sent with two different puncturing

schemes, it obtains additional information leading to an increased decoding probability.







1 � 1 � 35

1 Basics

1.14 EGPRS Channel Coding [cont.]

� MCSs are divided into 4 different families: A, A’, B and C� Each family has a different basic payload unit:

� 37 bytes: family A

� 34 bytes: family A’ (padding)

� 28 bytes: family B

� 22 bytes: family C

� When switching to MCS-3 or MCS-6 from MCS-8, 3 or 6 padding bytes, are added to the data bytes

�� Within a family different throughputs are achieved by transmitting a different number of basic payload units within one block

�� impact on retransmission

� Offset the GPRS disadvantage on retransmission







1 � 1 � 36

1 Basics


8.8

11.2

14.8

11.2 x 2 = 22.4

14.8 x 2 = 29.6

11.2 x 4 = 44.8

padding (MCS-3/6) 54.4

14.8 x 4 = 59.2

MCS-1

MCS-2

MCS-3

MCS-4

MCS-5

MCS-6

MCS-7

MCS-8

MCS-9

8.8 x 2 = 17.6

GMSK

8-PSK

Header + Protection

Maximum User Payload [kbit/s]

37 octets 37 octets 37 octets37 octets

MCS-3

MCS-6

Family A

MCS-9


MCS-2

MCS-5

MCS-7

Family B

22 octets22 octets

MCS-1

MCS-4

Family C

34 +3 octets34 +3 octets

MCS-3

MCS-6Family A’padding

MCS-8


� The main GPRS imperfections are linked to:

• the design of the GPRS coding schemes which were designed independently from the others with

their own data unit.

• the fact that once the information contained in an radio block has been transmitted with a

certain CS, it is not possible via the Automatic ReQuest for repetition (ARQ) mechanism to

retransmit with another CS.

- This could lead to the release of the TBF and to the establishment of a new one in order to

transmit the LLC frame.

� EGPRS coding schemes have been designed to offset this problem. Four MCS families have been

created with for each of them a basic unit of payload.

• This allows the re-segmentation of the RLC data blocks when changing of modulation and coding

schemes (within the same family).

- Example: if one MCS-6 radio block has not been received correctly by the receiver and if

radio conditions have degraded in the meantime, it is possible to re-send the same

information in two radio blocks with MCS-3 (more protection).

• The level of protection applied (MCS usage) in case of retransmissions is in line with the radio

conditions.

� The different code rates within a family are achieved by transmitting a different number of payload

units within one radio block. When 4 payload units are transmitted, these are split into 2 separate RLC

blocks (i.e., with separate sequence numbers).







1 � 1 � 37

1 Basics


MCS-9 basic payload unit = 37 bytes = 296 bits

MCS-9 RLC data block = 2 x basic payload unit =2* 296 bits = 592 bits

MCS-9 RLC payload throughput= 592 bits / 10 ms = 59.2 Kbps

USF HCSRLC/MAC

headerE FBI

RLC Data Block = 592 bits

BCS TB E FBIRLC Data Block =

592 bitsBCS TB

36 bits

3 bits

135 bits 1836 bits 1836 bits

SB=8 36 bits 124 bits 612 bits 612 bits 612 bits 612 bits 612 bits 612 bits

puncturingpuncturing

P3P1 P2 P1 P2 P3

45 bits 612 bits 612 bits

1392 bits

Rate 1/3 convolutional coding Rate 1/3 convolutional coding

puncturing

Interleaving of the EGPRS Radio Block over 4 consecutive TDMAs

EGPRS MCS-9 RADIO BLOCK

� MCS-9 Example:







1 � 1 � 38

1 Basics


8.80.531/3 rate convolutional

coding, punctured

GMSKMCS-1


coding, punctured

GMSKMCS-2


coding, punctured

GMSKMCS-3


coding, punctured

GMSKMCS-4


coding, punctured

8PSKMCS-5


coding, punctured

8PSKMCS-6


coding, punctured

8PSKMCS-7


coding, punctured

8PSKMCS-8


coding, punctured

8PSKMCS-9

Maximum data rate per TS (RLC payload) [kbps]

Code rate

Coding schemesfor RLC data block

Modulationschemes

Scheme

Uplink

&

Downlink

transfer







1 � 1 � 39

1 Basics

1.15 Radio Link Adaptation Overview

� (M)CS schemes are dynamically selected based on the quality of the radio channel, in order to maximize the throughput

� Two different mechanisms exists for GPRS and EGPRS:

� CS Adaptation in case of GPRS TBF mode and

� Link Adaptation (LA) in case of EGPRS TBF mode

� Selection of the most suitable (M)CS is based on measurements reported by the MS for the downlink path and by the BTS for the uplink path







1 � 1 � 40

1 Basics

1.16 Automatic ReQuest for repetition (ARQ)

� In the ARQ method, when the receiver detects the presence of errors in a received RLC block, it requests and receives a re-transmission of the same RLC block from the transmitter

� The retransmission can be performed using:

� Type-I ARQ mechanism. This applies for both GPRS and EGPRS mode

� Type-II hybrid ARQ mechanism, also called Incremental Redundancy (IR). This applies only for DL EGPRS mode

� IR is optional for the BTS, but is mandatory for the EGPRS MS (3GPP requirement)

B9!!! ARQ type-II applies for UL and DL EGPRS mode !!!







1 � 1 � 41

1 Basics

1.17 Type-I ARQ mechanism

� In the selective type-I ARQ mechanism, the receiver discards the erroneous blocks, and indicates in the acknowledgement messages the reference of these erroneous blocks for their retransmission. Then, the sending side has to retransmit the erroneous data RLC blocks

MS

Uplink RLC data block B1 / PDTCH (1)

MFS

Packet UplinkAck/Nack /PACCH (3)




The Block 2 has been

unsuccessfully received

MS retransmits the uplink

RLC data block B2

� With the type 1 ARQ mechanism, the decoding of a re-transmitted RLC block does not use the

previously transmitted versions (not correctly received) of this RLC block. The decoding of a RLC data

block is only based on the current transmission.

� The type 1 ARQ mechanism is always used for the GPRS







1 � 1 � 42

1 Basics

1.18 Type-I ARQ in GPRS

� GPRS CSs are designed independently from the others with its own basic payload unit size, so the family concept does not exists in GPRS

� Before its transmission over the radio interface, the LLC frame is segmented into payload units according to CS that will be used to transmit the radio block

� In case of erroneous reception, the RLC data block can be retransmitted only with the same CS (segmentation is not possible)

�� If the radio conditions have changed and the coding rate is not appropriate to them, the receiver will never be able to decode the retransmission of the RLC data block. This will lead to the release of the TBF and the establishment of a new one in order to transmit the LLC frame

� In order to avoid this problem, the choice of the CS on the network side has to be made carefully. This often results in an non-optimized use of the radio interface, leading to a reduction of network capacity compared with its theoretical capacity

GPRS D

RAW

BACK







1 � 1 � 43

1 Basics

1.19 Type-I ARQ in EGPRS

� MCSs have been designed to offset the GPRS disadvantage

� MCS family concept is applied

� In EGPRS, in case of retransmission request (type-I ARQ) for a RLC data block, the same or a next lower MCS within the same family is used

� The retransmission can be performed with or w/o RLC data segmentation (e.g. from MCS-9 to MCS-6 w/o, and MCS-6 to MCS-3 with segmentation)

� When one RLC data block is retransmitted with a lower MCS, the coding rate is decreased by two, but the redundancy transmitted is increased

�� That increases the capability to decode the radio block !

� Retransmission operates in connection with the link adaptation

� E.g. if the LA mechanism orders the usage of MCS-5 and the first transmission of an erroneous RLC block was with MCS-6, the transmission will be performed with MCS-3. The blocks that are sent for the first time will be transmitted with the last-ordered MCS







1 � 1 � 44

1 Basics

1.19 Type-I ARQ in EGPRS [cont.]

� Type-II ARQ (IR) is an efficient combination of 2 techniques:

� Automatic Repeat reQuest : in case of error detection in a received RLC block, a re-transmission of the same RLC data block is requested

� Forward Error Correction : adds redundant information to the user information at the transmitter, the receiver uses the info to correct errors causes by radio disturbances

� In the IR mechanism:

� The information which is sent first results from an initial “puncturing scheme” (PS1) applied to the encoded RLC data block

� If an error is detected by the receiver:

� the received message is stored

� selective retransmission of the RLC data block is requested

� a second “puncturing scheme” (PS2) is applied to the same MCS, by the sender

� the receiver decodes (combines) the resulting message together with the previously received message(s)

� multiple retransmission can be requested until decoding succeeds

� The type 2 ARQ mechanism or incremental redundancy (IR) is an ETSI function, mandatory for the EGPRS MS

receiver (downlink path) and optional for the BTS receiver (uplink path). In B8 release, the IR feature is only

available on the downlink path. It is important to notice that the IR feature is always running in the EDGE MS

receiver (except in case of MS memory shortage). The DL incremental redundancy is not used for the signaling

blocks, the GPRS data blocks and the data blocks in RLC unacknowledged mode. It is only used for the EGPRS data

blocks in RLC acknowledged mode.

� In the type II ARQ mechanism (IR):

• the first emission of a RLC data block is done using a first puncturing scheme (PS1),

• in case of re-transmission of this RLC block, the transmitter uses the same MCS or a MCS of the same family

than the one used for the initial block. On the DL path, depending on the value of the parameter

EN_FULL_IR_DL, re-segmentation of the RLC block may be performed or not,

• at the output of the demodulator, the receiver combines the information of soft bits corresponding to the

first transmission of the block and its different re-transmissions, thus increasing the decoding probability of

the RLC block.

• Remark : according to the 04.60 (RLC/MAC layers) GSM recommendation, the soft-combining inside the MS

receiver is only performed between an :

- MCSx block and MCSx block (that is the same MCS is used for the re-transmission),

- MCS9 block and an MCS6 block (in that case the RLC data blocks carry the same number of payload

units),

- MCS7 block and an MCS5 block (in that case the RLC data blocks carry the same number of payload

units).

� If the "MS OUT OF MEMORY" field is set by the mobile in the EGPRS Packet DL Ack/Nack message, the type I ARQ

shall apply in the MS receiver (ARQ without IR). This occurs when the memory for IR operation runs out in the MS

(that is when the memory of the MS is full due to the storage of the different versions of a RLC block not

correctly decoded).







1 � 1 � 45

1 Basics


puncturing

scheme 1

puncturing

scheme 2

Nack

MS BTS MFS

Data Block

Data Block

Data Block

Data Block

Data Block

Data Block

� (1) The BSS sends a DL data block using the puncturing scheme P1 and MCS-6. B1 is not successfully decoded by the MS. The MS stores the received block

� (2) The MS requests a selective retransmission of the erroneous block, in the next EGPRS Packet DL Ack/Nack

� (3) The MS retransmits the DL data block using a new puncturing scheme P2 and the same MCS-6.If the block header is correctly decoded, the MS decodes the data making soft combination with the previous transmission

� In the puncturing scheme selection for re-transmission, 2 cases have to be considered:

• if the selected MCS has not changed : if all the different punctured versions of the data block have

been sent, the procedure shall start over and PS1 shall be used, followed by PS2, then by PS3 (if

available for the considered MCS), so that the PS selection is cyclic,

• if the selected MCS has changed : the PS to be used is indicated by the table below.

Previous MCS New MCS Previous PS New PS

PS1 or PS3 PS1 MCS9 MCS6

PS2 PS2

PS1 PS3 MCS6 MCS9

PS2 PS2

MCS7 MCS5 PS1, PS2 or PS3 PS1

MCS5 MCS7 PS1 or PS2 PS2

All other combinations Any PS1







1 � 1 � 46

1 Basics


� B9 release: the IR mechanism is implemented in uplink and downlink

� This mechanism is associated with link adaptation in order to provide superior radio efficiency on the air interface

� IR feature is always running in the EGPRS MS receivers, except when a memory shortage is reported by the MS � the stored packets are discarded and type-I ARQ is set !

� Parameter for IR activation:

� EN_FULL_IR_DL which enable or disable the RLC data segmentation for retransmissions

� EN_FULL_IR_DL = disable; e.g. if MCS-5 is ordered by LA, and the first transmission was with MCS-6 then, the retransmission is performed with MCS-3 (segmentation on the initial RLC data block, ARQ Type-I)

� EN_FULL_IR_DL=enable; even if MCS-5 is ordered, the retransmission is performed with MCS-6 (no segmentation, ARQ Type-II)







1 � 1 � 47

1 Basics

1.20 (E)GPRS radio physical channel: PDCH Concept

� Packet Data Channel (PDCH)� (E)GPRS radio access method = GSM TDMA (8 timeslots per carrier)

� One PDCH represents a physical channel (1 timeslot) dedicated to packet data traffic (GPRS/EDGE), over the radio interface

� PDCH group� The available PDCH’s are grouped into “PDCH groups”

� One PDCH group contains consecutive timeslots (without TS holes)belonging to the same TRX, having the same radio configuration

� possible to have hopping and non hopping PDCH groups in one cell

� maximum number of PDCH groups/cell is equal to 16 (equal to maximum number of TRX / cell)� 16 TRX/cell achieved with help of the B7 feature “cell split over 2 BTS’s”, EVOLIUM™ BTS







1 � 1 � 48

1 Basics

1.21 (E)GPRS Multiframe

� 12 radio blocks (B0 to B11) form a 52-(E)GPRS multiframe� The frames 25 and 51 are idle frames and the frames 12 and 38 are

used for the PTCCH

One TDMA frame

= 8 TS (4,615 ms)

One PDCH

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 47 48 49 50

One 52 -multiframe (240 ms)

Block B0 Block B1 Block B2 Block B3

16

TPTCCH

Block B11

51

Xidle

0 1 2 3 4 5 6 7







1 � 1 � 49

1 Basics

1.22 (E)GPRS Logical Channels

� EGPRS is reusing the existing GPRS logical channels

� Packet logical channels are mapped in one physical channel (PDCH) using the technique of ‘multiframing’

� The sharing of the PDCH is done on blocks basis

� PBCCH (Packet Broadcast Control Channel) used for broadcasting system information (SI)

� PCCCH (Packet Common Control Channel) used to initiate packet transfer

� PRACH (Packet Random Access Channel)

� PPCH (Packet Paging Channel)

� PAGCH (Packet Access Grant Channel)

!!! MASTER CHANNEL ONLY !!!







1 � 1 � 50

1 Basics

1.22 (E)GPRS Logical Channels [cont.]

� PTCH (Packet Traffic Channel) used for user data transmission and its associated signaling

� PDTCH (Packet Data Traffic Channel) used to carry user data (LLC PDU segmented is RLC/MAC blocks)

� PACCH (Packet Associated Control Channel)

� Bidirectional channel, dynamically allocated on block basis, used to carry control data

� In Alcatel BSS is always allocated on one of the PDCHs on which PDTCHs are allocated

� PTCCH (Packet Timing Advance Control Channel) used for continuous timing advance mechanism

� Bidirectional channel allocated on the same PDCH as the PACCH







1 � 1 � 51

1 Basics

1.23 Master/Slave PDCH concept

� A PDCH which carries a PCCCH or/and a PBCCH channel is called Master PDCH (MPDCH)� MPDCH which carries the PBCCH is called Primary MPDCH

� Primary MPDCH is the ‘GPRS BCCH’

� MPDCH which carries only PCCCH is called Secondary MPCH

� All other PDCHs, active as slaves, are called Slave PDCH (SPDCH)

� B8 release:� MPDCHs are statically established only on BCCH TRX

� Up to 4 MPDCHs can be supported per cell (max Nb_TS_MPDCH=4)







1 � 1 � 52

1 Basics

1.24 Temporary Block Flow

� The packet data ‘call’ is a Temporary Block Flow (TBF)� For a data packet transmission, a temporary physical connection (TBF) will be set up as an unidirectional link

� Each TBF is unidirectional: Uplink TBF and Downlink TBF for the same mobile are uncorrelated

� One TBF allocates radio resources on one or more PDCH and comprise a number of RLC/MAC blocks carrying one or more LLC PDUs

� TBF is only temporary and maintained for the duration of the data transfer

� Either the mobile or the network can initiate a TBF

� Temporary Flow Identity (TFI):

• Each TBF is assigned a TFI by the MFS.

� Important:

• Since B7, it is possible to establish 32 TBFs per PDCH group (See sub-session 2.2 for ‘PDCH group’

definition).

� TBF

• is a group of blocks dynamically allocated to one MS for one transfer of RLC blocks in one direction

inside one cell.

• A Temporary Block Flow is a temporary, unidirectional physical connection across the Um interface,

between one mobile and the BSS. The TBF is established when data units are to be transmitted across

the Um interface and is released as soon as the transmission is completed.







1 � 1 � 53

1 Basics

1.24 Temporary Block Flow [cont.]

� TFI (Temporary Flow Identity)� RLC layer

� Each TBF is assigned a TFI by the MFS

� TFI is unique on a given PDCH, in a given direction

� A TBF is addressed by a Temporary Flow Identity (TFI)

� More than 32 TFI values per TRX (PDCH group) for each direction (i.e. DL and UL)

� TLLI (Temporary Logical Link Identity)� LLC layer

� The TLLI identifies the logical link between the MS and the SGSN

� The TLLI is allocated by the SGSN to the MS in Standby and Ready states







1 � 1 � 54

1 Basics

1.25 Resources Sharing

� Two different resource sharing mechanisms exists:� PDCH multiplexing

� Multislot usage

Allows optimum usage of the available radio resources

� PDCH Multiplexing� PDCH multiplexing refers to the sharing of one PDCH by more than two users

(TBFs)

� It occurs when there are more requests for PDCH resources than available PDCH’s

� A maximum number of UL/DL_TBF can share the same PDCH in UL and DL direction respectively

� MAX_UL_TBF_SPDCH=6; MAX_DL_TBF_SPDCH=10

� When a PDCH is shared between an UL GPRS TBF and a DL EGPRS TBF, then the DL EGPRS shall be limited to GMSK (i.e. MCS-4) � GPRS MS becomes candidate for radio resource reallocation







1 � 1 � 55

1 Basics

1.25 Resources Sharing [cont.]

� Multislot usage� Refers to the case when 1 user can request at once more than 2 PDCH resources for the data transmission

� Up to 5 PDCH on different (but consecutive) timeslots on the same frequency could be allocated to one mobile at the same time (MS multislot capability)

� B8 & B9 release supports 4+2 slots for Type 1 MS and 5+5 for Type 2 MS

� The PDCH blocks will be consecutively transmitted over the PDCH only if there is no user multiplexing







1 � 1 � 56

1 Basics


� PDCH Multiplexing example:

� lets assume that the data for user 1 has a length of 3 blocks (length of TBF 1=3 blocks) and is transmitted over PDCH #2

� as soon as one block of user 1 was entirely transmitted, another user 2can use the same PDCH #2 to transmit the blocks of its own TBF of e.g. length = 4 blocks, followed by the user 3 transmission...

� the blocks of user 1, user 2 and user 3 will not be transmitted in consecutive order:

� as soon as one block of user 1 is transmitted, another block of user 2 can be transmitted, continued with a block of the user 3 over the same PDCH #2

� Multislot usage example:

� User 1 has (1+1) and users 2 & user 3 have (3+1) MS multislot capability







1 � 1 � 57

1 Basics


� PDCH Multiplexing and Multislot Usage example

User 1:no multislot

capability

User 2:with multislotcapability

User 3:with multislotcapability

TFI = 5

TFI = 9

TFI = 13

PDCH 2

PDCH 1

PDCH 3

User 1 User 1

User 2 User 2

User 2

User 2

User 2

User 2

User 2

User 2

User 2

User 3

User 3

User 3

User 3

User 3

User 3 User 3

Multislot capability

Block n+1 n+2 n+3 n+4 n+5 ...

User multiplexing

n

User multiplexing







1 � 1 � 58

1 Basics

1.26 MS multiplexing co-ordination

� DL TBF (PDTCH and PACCH)

� MS decodes all blocks on its allocated PDCH

� The MS can identify the PDCH blocks intended for it by TFI present on the RLC block header

� UL TBF (PDTCH and PACCH)

� For an UL TBF, the mobile receives one USF (Uplink State Flag) per PDCH to be used during the TBF

� If the MS receives its USF on the DL block n of PDCH 5, it can transmit in UL using the block n+1 of PDCH 5

� Downlink PDTCH and PACCH blocks multiplexing:

• The multiplexing of the different MSs is performed thanks to the TFI which is present in the RLC block header.

• An MS decodes all the blocks of all its allocated PDCHs and keeps the blocks carrying its TFI in the

RLC header.

� Uplink PDTCH and PACCH for a UL TBF:

• At UL TBF establishment, a MS receives a USF (Uplink State Flag, 8 values, MAC header) per allocated

PDCH.

• If the MS receives its USF on the downlink block n of PDCH I, it can transmit in uplink using the block

n+1 of PDCH i.

� NB: the values of the USF are entirely dedicated to PDTCH and PACCH transfers. See further (MPDCH

and RRBP) The TFI is use in the UL as well: each mobile shall put its TFI in the UL header of the UL

blocks during a UL TBF, as well as in the RLC header of the UL PACCH blocks of a DL TBF. So we can say

that the de-multiplexing of the blocks is achieved by the use of a TFI.







1 � 1 � 59

1 Basics

1.26 MS multiplexing co-ordination [cont.]

� Uplink PACCH for a DL TBF :

� By the means of the polling mechanism, periodically an UL PACCH block is allocated during DL transfer, e.g. to allow an MS to request the establishment of an UL TBF by including a Channel Request description in a Packet DL Ack/Nack message

� the MS has no USF because it is involved in a DL TBF

� use of the RRBP (Relative Reserved Block Period) field transmitted in downlink

� RRBP values indicates the number of TDMA frames the MS shall wait before transmitting its uplink RLC/MAC block

� a special USF value is used: USF = no emission

� RRBP: Relative Radio Block Period

� Allocation of a PACCH block for the sending of acknowledgements in the UL of blocks received in the

DL:

• The MS has no USF because it is involved in a DL TBF

• Use of the RRBP field transmitted in the downlink (MAC header) in association with the TFI of the DL TBF in the RLC header.

• At the exact occurrence of the RRBP, a special USF value is used for the UL TBF taking place on the

same PDCH: USF=no emission.

� It is a semi-boolean parameter. The RRBP field of a RLC/LAC block is checked each time by the MS

whose TFI is written in the RLC header.

• When S/P is false, no UL PACCH is scheduled.

• When the RRBP field is valid, the value gives the number of blocks to wait before sending its PACCH

block in the UL

� S/P is false means MS has to send an acknowledgement message to the MFS.







1 � 1 � 60

� Example of a Uplink Block Flow scheduling:

1 Basics

1.26 MS multiplexing co-ordination [cont.]

DownlinkDownlinkDownlinkDownlink UplinkUplinkUplinkUplink

Blocknumber

TFI USF RRBP

Bn TFIa USFj

Bn+1 TFIb USFk PDTCHj

Bn+2 TFIa USFj +3 PDTCHk

Bn+3 TFIb FREE PDTCHj

Bn+4 TFIb NoEmission

PRACH

Bn+5 TFIb USFj PACCHa

Bn+6 TFIa USFk PDTCHj







1 � 1 � 61

1 Basics

1.27 GPRS mobility management (GMM) states for MS

Idle

Ready

Standby

GPRSattach

GPRSdetach

PDU transmissionTimerexpiry

Timerexpiry

� Idle� the MS is not attached to the

packet network: paging is not possible

� Ready� the MS location is known with

the cell accuracy

� Standby

� the MS is attached to the network: paging is possible

� the MS location is known with the RA accuracy

� Idle: the MS is not attached to the network: paging is not possible.

� Standby:

• the MS is attached to the network: paging is possible.

• the MS location is known in the CN with the RA accuracy.

� Ready:

• the MS location is known with the cell accuracy.

• timer T_READY keeps the MS in the Ready state just after data transfer.

� Packet Idle Mode:

• no Temporary Block Flow exists. Upper layers can require the transfer of an LLC PDU which, implicitly, may trigger the

establishment of TBF and transition to packet transfer mode.

• the MS listens to the PBCCH and to the paging sub-channel for the paging group the MS belongs to in idle mode. If PCCCH is not

present in the cell, the mobile station listens to the BCCH and to the relevant paging sub-channels.

� Packet Transfer Mode:

• In packet transfer mode, the mobile station is allocated radio resource providing a Temporary Block Flow on one or more

physical channels. Continuous transfer of one or more LLC PDUs is possible. Concurrent TBFs may be established in opposite

directions. Transfer of LLC PDUs in RLC acknowledged or RLC unacknowledged mode is provided.

• When selecting a new cell, mobile station leaves the packet transfer mode, enters the packet idle mode where it switches to

the new cell, read the system information and may then resume to packet transfer mode in the new cell.

� The timers regulating the transition between states are SGSN timers, not tunable in the BSS. Caution: Idle mode in GPRS and Idle

mode in GSM are two different states.

• A GSM MS in Idle mode is attached to a MSC and can be paged

• A GPRS MS in Idle mode is NOT attached to a SGSN, so it cannot be paged but can monitor the GPRS information broadcast in

the SI13 of the BCCH.

� Standby is the closest GPRS MS state to Idle GSM.

� The MS state in the SGSN shall be considered apart from the Packet Transfer Mode in the BSS:

• MS in Standby mode can be in Packet Transfer Mode.

• MS in Ready mode can be in Packet Idle Mode.

� The detach procedure is usually triggered by the MS. Three other types of detach are triggered by the CN:

• HLR Detach,

• SGSN Detach upon SGSN overload,

• SGSN Detach upon timer.







1 � 1 � 62

1 Basics

1.28 Radio Resource (RR) operating modes for MS

� Packet Transfer Mode (PTM)� MS is allocated radio resource on one or more PDCHs for the transfer of

LLC PDUs. Continuous transfer of LLC PDUs is possible

� Packet Idle Mode (PIM)

� No TBF exists and the MS is also not trying to establish an UL TBF

� GMM states versus RR operating modes:

PIM: There is no on-going TBF established and GMM ready timer is no more running

GMM Standby

PIM: TBF closed but GMM ready timer is still running

PTM: TBF openedGMM Ready

RR Operating ModesGMM States







1 � 1 � 63

1 Basics

1.29 Attach procedure

� Aim� to access to GPRS services, a MS must first make its presence known to

the network by performing a GPRS attach to the SGSN

� GPRS attach function is similar to IMSI attach

� MS authentication

� Ciphering key generation

� TLLI allocation (derived from the new P-TMSI)

� Subscriber profile request to the HLR







1 � 1 � 64

1 Basics

1.29 Attach procedure [cont.]

� Results� A logical link between the MS and the SGSN is created

� MS is in Standby state and may activate a PDP context

� MS location is known (RA accuracy)

� MS is available for paging via the SGSN

� Charging information is collected

� Combined GPRS and IMSI attach is possible for class A/B MS







1 � 1 � 65

1 Basics

1.30 PDP context activation

� Aim� in order to send and receive GPRS data, the MS must activate the PDP (Packet Data Protocol) address, which it wants to use

� Results

� the MS is known in the corresponding GGSN (the GGSN knows the SGSN where the MS is located) and data transmission with external data network can begin







1 � 1 � 66

1 Basics

1.31 Location management

MS enters in a new cell

New cell inside the current RA

MS in Ready state

New cell belongs to a new RA New cell belongs to a new LA

RA/LA updateRA updateCell update

� When the MS is in Ready State, it performs a “Cell Update”.

• The MS sends any LLC frame in the new cell with its TLLI in the header.

• The Cell and RAC information is added by the BSSGP at the programming of the BSSGP frame

� RA Update:

• The MS sends an RA Update Request message containing the identity of the MS, the old RAI and the

Update Type. The update type is either enter a new RA or periodical RA update.

• The BSS adds the cell global Identity when transferring the message into a BSSGP frame towards the

SGSN.







1 � 1 � 67

1 Basics

1.32 Routing Area

� As total paging is more frequent with GPRS service together withGSM paging, Routing Area (RA) was defined which may be smaller than Location Area (LA)

� One RA is a subset of one and only one LA

� RAI (RA Identity) identifies several cells

� The MS location in Standby state is known in the SGSN at the RA level

� The MS is paged in its RA when MT traffic (MS in Standby State) arrives at the SGSN

� One RA is served by only one SGSN







1 � 1 � 68

1 Basics

1.33 Network Mode of Operation (NMO)

- no Gs interface

- no MPDCH

CCCHCCCH

- no Gs interface

- MPDCH

PCCCHCCCH

III

- no Gs interface

- no MPDCH

CCCHCCCHII

- Gs interface(not applicable)Packet data channel

- Gs interface

- no MPDCH

CCCHCCCHI

- Gs interface

- MPDCH

PCCCHPCCCH

CharacteristicsPS Paging Channel

CS PagingChannelNMO

� Paging Coordination

� Since B7, all the possible combinations with the MPDCH are:

• NMOIII,

• NMOI with MPDCH.

� According to the NMO offered and the packet mode of the MS (Packet Transfer Mode or Packet Idle

Mode), the routing of the PS paging and the CS paging changes.

� The NMO setting is done from the OMC-R via the NETWORK_OPERATION_MODE parameter.







1 � 1 � 69

1 Basics

1.34 TBF establishment

� Several modes of TBF establishment in UL and DL exists:

� In PIM mode� UL TBF on the CCCH or PCCCH (with primary MPDCH activation)

� DL TBF on the CCCH or PCCCH (with primary MPDCH activation)

� In PTM mode� UL TBF establishment during a DL TBF on the uplink PACCH

� DL TBF establishment during a UL TBF on the downlink PACCH

� The TBF establishment is performed through two types of access requests:

� One phase access request

� Two phase access request

� B8/B9: The BSS preferentially establishes an EGPRS TBF to an EGPRS MS provided that an EGPRS Packet Channel request message has been received and that there are EGRPS resources (i.e. radio resources supported by an EGPRS capable TRX) available in the cell, otherwise a GPRS TBF will be established







1 � 1 � 70

1 Basics

1.35 UL TBF establishment on CCCH, 1 phase access

� MS is in PIM mode:

MS BTS BSC MFS

The MS

switches

on the

assigned

PDCH

TA calculationRACHChannel request + TA

Channel request

Resource

allocation

AGCH

Immediate assignment


TFI, USF, TAI, TA

Packet UL assignment, pollingTFI, USF, TAI

PACCHPacket UL assignment

Packet control Ack

PACCH Resource

activationRLC data block (TLLI, TFI)

PACCH

Packet UL Ack/Nack

PDTCH

1

2

3

TLLI, TFI

Also PRACHAlso PRACH

Also PAGCHAlso PAGCH

(EGPRS Packet)

(E)GPRS mode







1 � 1 � 71

1 Basics

1.35 UL TBF establishment on CCCH, 1 phase access

� 1 allocation of only one PDCH because the multi slot capability of the MS is not known

� Even if the Packet EGPRS Channel Request provides the MS multislotclass, only one PDCH is allocated

� 2 sending of the Packet UL assignment in order to force the MS tosend an acknowledgement (polling mechanism)

� 3 contention resolution mechanism :

� suppose two MS send a (EGPRS Packet) Channel Request at the sametime

� each MS sends its TLLI (and TFI)

� the TLLI is present in the acknowledgement from the MFS

� the MS with the wrong TLLI is discarded







1 � 1 � 72

1 Basics

1.36 UL TBF establishment on CCCH, 2 phases access


MS BTS BSC MFS

The MS

switches

on the

assigned

PDCHs

TA calculationRACH

Channel request + TA

Channel request

Resource

allocation

AGCH


Immediate assignmentTBF starting time, TA

PACCHPacket resource request

Resource

activation

Packet UL assignmentPACCH

Packet UL assignment, polling

Packet resource request

TFI, USFs, TAI, TLLI

PACCH

Packet control AckPacket control Ack

Single block

allocation

TLLI

RLC data blockPDTCH

Also PAGCHAlso PAGCH

Also PRACHAlso PRACH

(EGPRS Packet)

(E)GPRS mode







1 � 1 � 73

1 Basics

1.36 UL TBF establishment on CCCH, 2 phases access [cont.]

� 2 phases access is necessary when the MS wants either to :

� Use RLC unacknowledged mode

� Give its multislot class

� Give QoS parameters (Peak_Throughput_Class, Radio_Priority)

� Main difference: � Packet Resource Request message







1 � 1 � 74

1 Basics

1.37 DL TBF establishment on CCCH


MS BTS BSC MFS

LLC PDUResource

allocation


TFI, TAIImmediate assignmentPCH

Packet DL assignment, pollingTFI, TAI

PACCHPacket DL assignment

PACCHPacket control Ack

Packet control AckTA calculation

Timing Advance / Power control

PACCHTA / PC

PDTCHRLC data block

1 PDCH

allocated

4 access bursts

PDCH(s)

allocated

Also PPCH







1 � 1 � 75

1 Basics

1.38 System information broadcasting on BCCH

� The BCCH indicates if GPRS is supported in the cell:

� SI3/4: GPRS supported or not

SI13 position on BCCH used for GPRS

� SI3: RA_COLOUR (routing area color) field present if GPRSsupported

� If GPRS is supported :

� SI13 is broadcasted on the BCCH

� SI13 broadcast instead of retransmission of SI 1

� Note: do not confuse RA_COLOUR and RA Code. The former is used as a flag which has two uses for the

MS entering a new cell:

• to know if the GPRS service is supported in the cell (RA_COLOUR has a value different from -1).

• to trigger an RA update when the value of the RA_COLOUR changes. It is easy to monitor because it is

broadcast often.

• The Routing Area Code is necessary for the RA update procedure (message content).

• The SI13 takes the place of a few SI1 occurrences.







1 � 1 � 76

1 Basics

1.38 System information broadcasting on BCCH [cont.]

� SI 13 content (non exhaustive):

� RAC: routing area code

� NMO: network mode of operation

� PAN_DEC, PAN_INC, PAN_MAX: radio link supervision

� ALPHA: GPRS uplink power control

� T_AVG_T, T_AVG_W: calculation of average levels

� PC_MEAS_CHAN: level measurements on BCCH/PDCH

� NETWORK_CONTROL_ORDER: packet cell re-selection mode

� Access Burst Type : 8 bit or 11 bit access burst

� EGPRS_PACKET_CHANNEL_REQUEST: EGPRS capable MS shall use EGPRS PACKET CHANNEL REQUEST message for uplink TBF establishment on the (P)RACH (En_EGPRS = True)

� BEP_PERIOD: Bit error probability (BEP) filter averaging periodEGPRS c

ell

� The MS has to get SI13 information on a regular basis:

• each time the SI13 content is updated (PSI field = SI13_CHANGE_MARK set to 1).

• every 30 seconds max (even if the TBF has to be interrupted).

• Through 2 different ways: SI13 on the BCCH or PSI13 in a PACCH block.

• The MS has always the time to switch on PSI13 in NMOIII and/or NMOI with a Master PDCH

because PBCCH blocks are always after a I or X TS within the 52 multi-frame.

� Access Burst Type: it defines the access burst (8 bits or 11 bits) to be used on the PRACH, PTCCH and

the “Packet Control Ack” on a PACCH.

� When the Master Channel is present in the cell, the System Information Type 13 message has different

contents from those described above. It mainly consists of:

• The radio description of the Primary Master Channel (in terms of time slot number, training

sequence code and frequency parameters).

• One GPRS Mobile Allocation (MA), if frequency hopping is used for GPRS. This is the GPRS MA of

the Primary Master Channel, if hopping. If the Primary Master Channel is not hopping, the MA

corresponds to the hopping TRX(s) used for GPRS, if any.

� Three modes of cell reselection have been defined by the 3GPP Standard for GPRS MSs. These

Network Control (NC) modes, known as the NC0, NC1 and NC2, are shortly described below:

• NC0: the GPRS MS performs autonomous cell reselection without sending measurement reports to

the network.

• NC1: the GPRS MS performs autonomous cell reselection. Additionally it sends measurement

reports to the network.

• NC2: the GPRS MS shall not perform autonomous cell reselection. It sends measurement reports

to the network. The network controls the cell reselection.







1 � 1 � 77

1 Basics

1.39 System information broadcasting on PBCCH

� Presence of a PBCCH (primary MPDCH) in the cell is indicated by a PBCCH description in the SI13 message

� Primary MPDCH presence is possible only in NMO I or in NMO III

� Secondary MPDCHs presence are in indicated in PSI 2 message broadcast on the PBCCH channel

� All (E)GPRS MS monitor the PBCCH to receive the PACKET SYSTEM INFORMATION messages (PSI)

� Without PBCCH configured in the cell:

� In PIM, MS receive SI13 sent on BCCH

� In PTM, MS receive PSI 13 (=SI13) sent on PACCH

� Not possible to indicate to a MS, GPRS re-selection parameters (C31 and C32 criteria)

� Cell Parameters

• NMO, MS Timers, DRX info, RLS parameters, etc.

� PRACH access control parameters

• access burst type, access control class, etc.

� PCCCH organization parameters

• BS_PBCCH_BKLS, BS_PAGCH_BLKS_RES, BS_PRACH_BLKS

� The GPRS cell adjacencies are the same for a MS in Packet Idle Mode as for a MS in Packet Transfer

Mode. The GPRS cell adjacencies are equal to CS cell adjacencies.







1 � 1 � 78

1 Basics

1.39 System information broadcasting on PBCCH [cont.]

� PSI 1 (sent also periodically in PTM on PACCH)

� Cell and BSS parameters

� PRACH access control parameters

� Description of the configuration of the packet control channels

� number of blocks per 52 multiframe

� Power control parameters

� PSI 2 (sent also periodically in PTM on PACCH)

� Cell allocation

� GPRS mobile allocation : HSN + list of frequencies

� PCCCH description : list of TS and frequency configuration

� Circuit-switched parameters

� Cell Identification : CI, RAC, LAC, MNC, MCC

� PSI3, PSI3bis:

• One PSI3 instance shall be sent and, as a minimum, one PSI3bis instance shall be sent as well

• There may be up to 16 PSI3bis instances.

• Reselection parameters: C31_HYST, C32_HYST, GPRS_CELL_RESELECT_HYST, PRIORITY_CLASS, HCS_THR, RA_RESELECT_HYSTERESIS

• Neighbor cell parameters: BSIC, BCCH frequency, SI13 PBCCH location, GPRS_RXLEV_ACCESS_MIN, GPRS_MS_TXPWR_MAX_CCH, GPRS_TEMPORARY_OFFSET, GPRS_PENALTY_TIME, GPRS_RESELECTION_OFFSET.

• Up to 32 neighboring cells may be defined. The field Same_RA_As_Serving_Cell provides

complementary information for reselection process.







1 � 1 � 79

1 Basics

1.39 System information broadcasting on PBCCH [cont.]

� PSI 3 / 3bis� BA(GPRS) list (identical to GSM BA list, neighboring cells BCCH)

� Cell selection and re-selection parameters for (non-)serving cells

� LSA identification of serving and neighboring cells

� PSI 8 CBCH information (TS, freq., if there is CBCH in the cell)







1 � 1 � 80

1 Basics

1.40 (E)GPRS Transmission Aspects

� One Abis link is made of 31 64 kb/s timeslots

� A 16 kb/s transmission channel is called a nibble

� One timeslot is made of 4 nibbles

� A transmission channel established for carrying (E)GPRS traffic is called a GCH (GPRS channel). One GCH uses one Abis nibble and one Ater nibble

� Two main types of Abis nibbles:

� Basic nibbles

� Carry CS traffic

� Carry PS traffic but only coded with (M)CS-1 or (M)CS-2

� Located on Primary Abis

� Extra nibbles

� Come from additional Abis timeslots for support of high speed packet traffic

� Carry PS traffic only

� Located on Primary or Secondary Abis

!!! MODIFIED FOR B9 !!!







1 � 1 � 81

1 Basics

1.40 TRX Classes Concept

� To support high data throughputs, Alcatel has developed a solution, which aims at providing the best trade-off between offered radio throughput and impact on the telecom resource consumption

� This solution is based on the concept of multiple classes of TRX, which support more or less data throughput. The higher the packet class, the higher the maximum data throughput, the higher the impact on BSS Telecom resources

� Five TRX classes (1 to 5) have been defined

� The Operator defines per cell the number of TRXs of each class







1 � 1 � 82

1 Basics

1.40 TRX Classes Concept [cont.]

TRX Packet Class

G3 or G4 TRX

Class 1“Simple”

Class 2“Double”

Class 3“Triple”

Class 4“Quad”

GPRS CS 1,2EDGE MCS 1,2

GPRS CS 1,2,3,4EDGE MCS 1,2,3,4,5

GPRS CS 1,2,3,4EDGE MCS 1,2,3,4,5,6

GPRS CS 1,2,3,4EDGE MCS 1,2,3,4,5,6,7,8

Supported (Modulation and) Coding schemesSupported (Modulation and) Coding schemes

Class 5“Quintuple”

GPRS CS 1,2,3,4EDGE MCS 1,2,3,4,5,6,7,8,9

Max 22 kbps

Max 30 kbps

Max 54 kbps

Max 59 kbps

Abis TS per TRX

2

4

6

8

10

Max 12 kbps

� EGCH

• An EGCH is made up of a pool of GCHs (from 1 to 5): One main GCH and a pool of auxiliary GCHs (the

GCH uses the basic 16k Abis nibble).

� TRX class

• The TRX class is defined at MFS level. For a TRX class n, the MFS will use n GCHs to establish one

EGCH. The TRX class varies with the hardware TRX capabilities (TRX type, Hardware PS capability).

Higher the TRX class is, higher the PDCH throughput is.

� AterMux resources allocation

• In case of EGCH establishment, from one to five AterMux nibbles will be necessary. Nibbles have not

to be contiguous.

• These nibbles will be taken:

- on free nibbles of at least one already switched 64 Kbit/s channel, or,

- on free nibbles of one or more already switched 64 Kbit/s channels and on an additional 64 Kbit/s

channel, switched for this purpose, or,

- on 1 or 2 additional 64 Kbit/s channels, switched for this purpose.

• When possible, the first possibility will be chosen.

• When establishing a PDCH, the number of GCH links per radio time slot is determined according to

the TRX class, the PDCH type (SPDCH/MPDCH), and the AterMux congestion state.

� Abis Interface

• Several Abis nibbles are also used to handle a throughput higher than 16Kbit/s. Abis configuration is

static due to hardware constraints.

• Depending on the requested throughput, a radio time slot needs up to 4 extra Abis nibbles in addition

to the basic one.

• As all radio time slots of a TRX must have the same throughput capability, a TRX needs up to 8 extra

Abis time slots. These extra Abis time slots are called a TRX transmission pool.







1 � 1 � 83

1 Basics

1.40 TRX Classes Concept [cont.]

� Example 1: TRX class 1, up to CS-2 / MCS-2

� Example 2: TRX class 4, up to CS-4 / MCS-8

BasicTimeslots

TRX Abis

TS4 TS5 TS6 TS7

TS0 TS1 TS2 TS3TS0 TS2TS1 TS5TS4TS3 TS7TS6

BasicTimeslots

Abis

TS4 TS5 TS6 TS7

TS0 TS1 TS2 TS3

TS1 TS2 TS3

TS4 TS5 TS6 TS7

TS0 TS1 TS2 TS3

TS4 TS5 TS6 TS7

TS0 TS1 TS2 TS3

TS4 TS5 TS6 TS7

Basic Nibble

Extra Nibbles

TS0

Timeslots

6 Extra

TRX

TS0 TS2TS1 TS5TS4TS3 TS7TS6

Radio Timeslot

1 PDCH = 4 terrestrial nibbles

= 1 basic nibble also used for voice

+ 3 additional nibbles used only for

packet traffic







1 � 1 � 84

1 Basics

1.41 Two Abis Links per BTS

BSC

BTS

EVOLIUMBTS

Primary Abis

Secondary Abis

Primary Abis

Secondary Abis

EVOLIUMBTS

BTS

Topology 1

Topology 2

� The secondary Abis is fully dedicated to packet data

� Two topologies exists







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2 B9 features







1 � 1 � 86

2 B9 features

2.1 Enhanced Packet Cell Reselection (R4 MSs)

� In B9 a number of procedures have been introduced to achieve better performances for GPRS cell reselections:

� Packet PSI Status procedure

� reducing the duration of the phase where the MS acquires PSI in the target cell

� Packet SI Status procedure, same scope as above for SI in the target cell

� Network Assisted Cell Change procedures

� reducing, in NC0 and NC2 mode, the duration of the phase where the MS acquires target cell (P)SI, in the serving cell

� CCN mode procedure (Cell Change Notification)

� allowing, in NC0 mode, the MS to indicate its wish to perform a cell reselection

� Cell System Information distribution

� Cell ranking with load criteria







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2.1.1 Radio Network Impact

� The B9 added improvements allow reducing the time dedicated to aCell Reselection in packet mode.

� These sub-features impact traffic model, allowing faster CR to a new cell or less number of CRs performed in a cell, will result in a higher aggregated throughput in the cell.







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2.2 Extended Uplink TBF Mode

� This feature allows improving access time to the GPRS network

� ping test down to 350 ms

� It also improves the throughput in some cases.

� The feature main benefits are: reduced (may be 0) delay before next UL transmission (no new TBF to establish) and

reduced DL TBF establishment, when it follows an UL TBF. Expected effects:

• In uplink, it can avoid to re-establish TBF for subsequent burst of data from the same higher layer transaction,

and it avoids to establish a new TBF if new data arrive during countdown procedure on the current TBF.

• In uplink, it can avoid to re-establish TBF for subsequent burst of data from the same higher layer transaction,

and it avoids to establish a new TBF if new data arrive during countdown procedure on the current TBF.

• in downlink, it allows to perform more often the TBF establishment on concurrent TBF and it saves the DL

bandwidth by sending dummy UI commands (on the DL TBF is in delayed release state) if a concurrent TBF exists.

• Both effects are expected to improve the end-to-end transmission delay and consequently to reduce the transfer

duration.

� The mechanism proposed has the following characteristics:

• Extended Uplink TBF shall be used whenever allowed by the MS capabilities.

• The BSS shall be able to acquire the MS capability as fast as possible, using the Radio Access capability update

procedure (or information stored in other GPUs).

• When the MS does not support the extended UL TBF mode , the BSS will use the normal release procedure, and

apply the “delayed Final PUAN” procedure if T_Delayed_final_PUAN is not 0.

• If the MS capabilities are not yet known by the BSS at UL TBF establishment, the BSS shall be able to switch to

extended UL TBF mode if the MS capabilities are received before the release of the uplink TBF has been

initiated.

• During the uplink TBF extension (i.e., after the last LLC frame has been received from the MS and no data is

being transmitted by the MS), it allows the network to initiate sending of data to the MS without performing a

downlink TBF establishment oncommon control channels.

• It allows the MS to send data from newly arrived LLC frames after the countdown has started.

• While in the delayed state the network must allocate some radio blocks, to allow the MS to restart the uplink

transfer whenever required by the application.







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2.2 Radio Network Planning Impact

� Traffic model changes: the feature will modify the number of UL TBF activation+release on PACCH for all TCP/IP based applications and WAP.

� The feature will also modify the average duration of an uplink TBF, and as a consequence increase the number of MS multiplexed in uplink.

� If necessary to reserve a certain bandwidth in uplink for QoS, then the maximum number of MS in UL on the concerned PDCH should be limited. (the current default value is of 5 MS multiplexed in uplink)







1 � 1 � 90

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2.2 Radio Network Planning Impact [cont.]

� Some parameters are to be handled in order to set up and configure this feature:

� EN_EXTENDED_UL_TBF: Enable the extended TBF mode feature on the uplink.

� T_MAX EXTENDED_UL: Maximum duration of the extended uplink TBF phase. Recommended rule: value between 1s and 2s.

� EN_FAST_USF_UL_EXTENDED: Enable the transmission of USF every 20ms in extended mode, when the extended UL TBF feature is activated.

� EN_RA_CAP_UPDATE: Enable the Radio Acces Capability update on Gb. Recommended rule: should be enabled if EN_EXTENDED_UL_TBF is enabled and RA cap. update is supported by SGSN.

� It is recommended not to activate simultaneously extended UL TBFfeature (flag EN_EXTENDED_UL_TBF) and the DL PDU rerouting feature (flag EN_AUTONOMOUS_REROUTING).

Fast USF UL extended : to keep the link alive in order to be ready as soon as needed. If n MSs in extended,

then USF for 1 MS sent every n x 20ms.

RA CAP Update : the MFS can request the RA capabilities of the MS to the SGSN (based on IMSI)







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2.3 Enhanced support of E-GPRS (EDGE) in uplink

� In B9 support of MCS-5 to MCS-9 coding schemes in UL was introduced.

59.2 kbit/sMCS-98-PSKB9





17.6 kbit/sMCS-4GMSKB8




20.0 kbit/sCS-4GMSKB8




User datarate

Codingscheme

ModulationRelease







1 � 1 � 92

2 B9 features

2.3 Enhanced support of E-GPRS (EDGE) in uplink [cont.]

� In B9 release, “Incremental Redundancy” may be activated for both the DL and UL paths. Thanks to Incremental Redundancy, the link adaptation procedure can be more aggressive: if the chosen MCS is a bit too optimistic, IR increases the probability of data recovery and increases data rates considerably specially in poorer radio conditions for higher MCS’s.

� The link adaptation mechanism in UL is based on measurements (MEAN_BEP, CV_BEP) done by the BTS on the radios blocks receivedfrom the mobile. To take into account MCS-5 to MCS-9, the BSS algorithm for link adaptation needs new link adaptation MEAN_BEP/CV_BEP tables. These tables are the same as the one already used for DL.







1 � 1 � 93

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� 8-PSK in the UL should be considered in the planning tools for the throughput and coverage estimation (based on interference calculation). It impacts cell range estimates if the link-budget is UL limited.

� The IR gain should also be considered in the throughput estimation :

� 2 dB can be taken for the average IR gain.







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2.4 Counter Improvements for Release B9

� “Counter Improvements for Release B9” feature covers four candidate “sub-features” for B9:

1. Support of distributions: It introduces a new concept of counters called distributions to obtain improved statistics on (E)GPRS resource usage.

2. Consolidation of cell indicators at GPU level: It allows an operator to consolidate each indicator defined at cell level per GPU. This operation is very useful to follow possible lacks of GCH or GPU resources in a given GPU.

3. Counters defined at TRX level: It introduces a few counters defined at TRX level to follow the radio and transmission resource usage.

4. New MFS counters: It consists in defining a few new counters to ease the dimensioning and optimisation of (E)GPRS networks.







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2.4 Counter Improvements for Release B9 [cont.]

� Support of distributions

Same rationale as P455b but for the DL directionDISTRIB_DL_PDCH_UNIT_ALLOCP455b

The distribution of the number of PDCH units assigned to an UL TBF is required to check whether

non-optimal allocations come from a lack of radio resources. In this case, parameters like

MAX_PDCH, MAX_PDCH_HIGH_LOAD can be increased.

DISTRIB_UL_PDCH_UNIT_ALLOCP455a

Same rationale as P454a but for the DL directionDISTRIB_DL_TBF_VOLUMEP454b

The distribution of the UL LLC volume is interesting to:

-Differentiate the type of traffic (GMM signalling, Web browsing, FTP transfers, etc.).

-Check the validity of the UL LLC volumes (measured in bytes) reported by the PM counters. For

instance, the average is meaningless if long TBFs generating high UL LLC volumes are not

distinguished from short TBFs generating small UL LLC volumes.

-Justify certain bad throughputs observed in the fields.

-The corresponding thresholds should be tuneable to allow isolating a given traffic for a deep field

analysis.

DISTRIB_UL_TBF_VOLUMEP454a

Same rationale as P453a but for the DL directionDISTRIB_DL_TBF_DURATIONP453b

The distribution of the UL TBF duration is interesting to:

-Differentiate the type of traffic (GMM signalling, Web browsing, FTP transfers, etc.).

-Check the validity of the UL TBF duration reported by the PM counters. For instance, the average is

meaningless if long TBFs are not distinguished from short TBFs.

-Justify certain bad throughputs observed in the fields.

-The corresponding thresholds should be tuneable to allow isolating a given traffic for a deep field

analysis.

DISTRIB_UL_TBF_DURATIONP453a

RationaleMnemonicCounter

� Support of distributions

• Actually, “Support of distributions” is an enhancement for the feature “Radio Measurement Statistics

(RMS)”, introduced on release B7.2, in order to get statistics on radio measurements such as RXLEV,

RXQUAL, interference level, timing advance, MS or BS transmitted power, etc.

• This sub-feature introduces a new concept of counters to monitor PS resource usage. The existing PS

counters count a number of events occurring during the reporting period (i.e. every hour). However,

such counters do not allow retrieving the distribution of the events. For instance, existing counters

allow evaluating the averaged duration of the TBFs. However, it is interesting to know what is the

proportion of short TBFs compared to long TBFs, to evaluate the type of GPRS traffic, to understand

the throughput measured in the fields, etc.. New counters, called “distribution”, were introduced. The

B7.2 RMS feature is based on the following principles:

- The operator can launch RMS from the OMC-R on a per cell or per BSC basis for a given duration (up

to 23 hours).

- The radio measurements are monitored the closest to the observed functions, i.e. in the BTS.

- During the observation period, it is possible to launch extended measurement reporting in order to

get measurements on radio frequencies not used for CS/PS traffic in the cell.

• The measurements are usually reported in vectors made of 10 values (or matrixes made of several

vectors). The ranges of each vector are defined by 9 thresholds. These thresholds are changeable at

the OMC-R.







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� Consolidation of cell indicators at GPU level

� The sub-feature consists in allowing the operator to consolidate cell counters P105c/d/e/f/g/h at GPU level.Also, without this consolidation, it is up to the MFS to perform the consolidation, which is in contradiction with the usual principles. Indeed, it is not the role of the MFS to perform computation on counters.

CellNumber of UL TBF establishment failures due to a lack of transmission resources.P105h

CellNumber of DL TBF establishment failures due to a lack of transmission resources.P105g

CellNumber of UL TBF establishment failures due to CPU processing power limitations of the

GPU.

P105f

CellNumber of DL TBF establishment failures due to CPU processing power limitations of the

GPU.

P105e

CellNumber of UL TBF establishment failures due to GPU congestion.P105d

CellNumber of DL TBF establishment failures due to GPU congestion.P105c

InstanceDefinitionReference







1 � 1 � 97

2 B9 features


� New MFS counters

Same rationale as P98f but for the DL direction.NB_SUSP_DL_TBF_RELP98e

This counter is defined to obtain a more accurate

indicator for TBF drops. Operators are carefully analysing

the TBF drop rate that it is one of the main (E)GPRS QoS

figures.

NB_SUSP_UL_TBF_RELP98f

This counter is used to quantify the part of the GMM

signalling traffic over the whole (E)GPRS traffic. For

instance, this information is required to know how many

radio resources should be configured to carry only GMM

signalling traffic.

CUMULATED_TIME_PDCH_DL_TBF_GMM_SIG_CELLP452

Same rationale as P451a but for the DL direction.CUMULATED_TIME_PDCH_DL_TBF_CELLP451b

This counter is used with P38f to quantify the

overlapping of the UL TBFs on the PDCHs. For instance, a

high overlapping factor can explain why the throughputs

observed in the fields are low.

CUMULATED_TIME_PDCH_UL_TBF_CELLP451a

Same rationale as P38f but for the DL direction.CUMULATED_TIME_PDCH_USED_DL_CELLP38e

This counter is used with P451a to quantify the

overlapping of the UL TBFs on the PDCHs. For instance, a

high overlapping factor can explain why the throughputs

observed in the fields are low.

CUMULATED_TIME_PDCH_USED_UL_CELLP38f

RationaleMnemonicCounter

Class BClass B mobile phones can be attached to both GPRS and GSM services, using one service at a time. Class B

enables making or receiving a voice call, or sending/receiving an SMS during a GPRS connection. During voice

calls or SMS, GPRS services are suspended and then resumed automatically after the call or SMS session has

ended.

� This is suspend / resume







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� The new counters and distributions should allow us to improve the existing (E)GPRS traffic model (i.e. better accuracy of the model can be achieved) but no impact on radio and other telecom performances is expected.







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2 B9 features

2.5 Autonomous Packet Resource Allocation

� The purpose of this feature is to give to the MFS all the radio timeslots that are usable for PS traffic, according to the whole BSS load (CS and PS loads). The MFS needs no more to request radio timeslots to the BSC; instead the MFS is always aware of all theavailable radio timeslots.







1 � 1 � 100

2 B9 features

2.5 Autonomous Packet Resource Allocation [cont.]

� Main principles:

� CS and PS allocation separation with expected result of higher mean TBF throughputs.

� To give to the MFS all the radio timeslots that are usable for PS traffic

MIN_SPDCH

MAX_SPDCH_HIGH_LOAD

MAX_SPDCH

MAX_SPDCH_LIMIT

reserved for PS priority for PS priority for CS reserved for CS

Max PS traffic when high CS traffic

Max PS traffic without CS traffic

Max CS traffic without PS traffic

� MAX_SPDCH_LIMIT is computed by the BSC and defines the number of SPDCHs that are allocated to the

MFS (based on the whole BSS load)

� The allocated SPDCHs are always those having the highest priority for PS allocations and their positions

are provided to the MFS within a new message called Radio Resource (RR) Allocation Indication message

� TBFs allocated in the MAX_SPDCH_HIGH_LOAD zone cannot be pre-empted (T1 re-allocation) when

MAX_SPDCH_LIMIT value decreases

� Periodically, the MFS sends to the BSC a Radio Resource Usage Indication message. This message

contains the allocated SPDCHs in the MFS as well as their usage. This message is used by the BSC to

estimate the PS load

� If required, the MFS may pre-empt a few SPDCHs to give them back to the BSC. The MFS uses the same

Radio Resource Usage Indication message to indicate to the BSC the de-allocated SPDCHs and to

acknowledge the allocation of new SPDCHs

− Reserved for PS: This zone defines the number of radio resources reserved for PS traffic. No CS traffic can

be carried in that zone. The size of this zone is defined by the parameter MIN_SPDCH.

− Priority for PS: This zone defines a number of radio resources where CS and PS traffic can be carried, but

the preference is given to PS traffic in that zone. The size of this zone is defined by the parameters

MAX_SPDCH_HIGH_LOAD and MIN_SPDCH.

− Priority for CS: This zone defines a number of radio resources where CS and PS traffic can be carried, but

the preference is given to CS traffic in that zone. The size of this zone is given by the difference between the

parameters MAX_SPDCH and MAX_SPDCH_HIGH_LOAD.

− Reserved for CS: This zone defines the number of radio resources reserved for CS traffic. No PS traffic can

be carried in that zone. The size of this zone is defined thanks to the parameter MAX_SPDCH.







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� Autonomous Packet Resource Allocation

� -100 ms gain in the DL or UL TBF establishment duration

� As the maximum number of radio resources is allocated to the MFS, the TBF establishment duration (DL or UL) is reduced compared to the B8 solution (if the MFS requests for additional radio resources to establish the TBF).

� This could lead to an increase in the average TBF throughputs at cell level.







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2 B9 features

2.6 2G/3G Inter-working

� Improve the 3G neighborhood description in 2G cells

� Consistent with the cell reselection strategy in B9

� 2G/3G Interoperability” feature comprises two sub-features:

� Improved 3G cell reselection

� Neighbour UTRAN FDD cells are provided in SI2quater (new message)

� UTRAN frequencies are defined at GSM cell level (3/cell at max)

� Neighbour UTRAN FDD cells are described at the OMC with their UTRAN FDD frequencies Scrambling Codes and Diversity

� Load based 3G HO filtering

� The BSS may reject an external HO incoming from the UTRAN, provided the HO has not been triggered by an emergency cause

� Current load will be compared with a new threshold, namelyTHR_CELL_LOAD_3G_REJECT







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2 B9 features

2.6 2G/3G Inter-working [cont.]

� Improved 3G cell reselection

� The B9 “Improved 3G cell reselection” feature allows the operator to declare per 2G cell basis the 3G neighbor cells (the FDD UMTS frequencies and the scrambling codes). Maximum 3 FDD UMTS frequencies may bedeclared per cell basis. When knowing in advance the frequency and the scrambling code of a 3G cell, an MS should require 10 to 20ms tosynchronize on that cell.







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2 B9 features

2.6 2G/3G Inter-working [cont.]

� Load based 3G HO filtering

� Regarding the current load, the BSS may reject an external hand-over coming from the UTRAN, provided the hand-over has not been triggered by an emergency cause, i.e. provided the hand-over request does not carry a cause type uplink/downlink quality/strength.


� These sub-features impact traffic model, allowing faster 2G-to-3G cell reselection to a new cell or denying incoming handovers in a lodedcondition. It will result in a higher aggregated throughput in the cell or in less call drops experienced by a source 3G cell.







1 � 1 � 105

2 B9 features


� These sub-features impact traffic model, allowing faster 2G-to-3G cell reselection to a new cell or denying incoming handovers in a loaded condition. It will result in a higher aggregated throughput in the cell or in less call drops experienced by a source 3G cell.







1 � 1 � 106

2 B9 features

2.7 M-EGCH Statistical Multiplexing

� This feature provides a solution to share the Ater and Abis nibbles between the radio timeslots of a TRX so that the transmission resources left available by a PDCH can be re-used by other PDCHsas long as those PDCHs belong to the same TRX. Thus allows reducing the waste of transmission bandwidth on the Ater and Abisinterfaces.

� Terminology

• M-EGCH

- The term M-EGCH (Multiplexed-EGCH) is used to refer to a link established between the MFS and

the BTS. An M-EGCH is defined per TRX (instead of an EGCH per radio timeslot in release B8).

• GCH

- A GCH is the 16kb/s channel between the MFS and the BTS. It is composed of an Ater nibble and an

Abis nibble cross-connected together in the BSC. The MFS or the BTS periodically send blocks on a

GCH every 20 ms.

• GCH frame

- In 20 ms period (also called block period), a number of 320 bits of this GCH can be used: this is the

frame.

• Segment

- A segment is formed by a part of an RLC block (after its segmentation on the M-EGCH link) and a

GCH header (different for first segment and subsequent segments). RLC data might be padded or a

segment can be a “no-data segment”.

- Note that in B9 a frame can be constituted of several segments belonging to different RLC blocks as

now all the RLC blocks sent on several PDCHs of a TRX are multiplexed on the same M-EGCH link.

Padding bits are added to the RLC blocks’ segments to fill the frame to 320 bits.







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2.7 M-EGCH Statistical Multiplexing [cont.]

� The M-EGCH Statistical Multiplexing solution allows to share a given number of GCHs at a TRX level, i.e between the radio timeslots of one TRX, so that:

� the transmission resource left available by one TBF mapped on a set of RTS and being idle (eg, in establishment or delayed release phase) is automatically reused by another TBF mapped on the same RTSs or on another set of RTSs (as long as those sets of RTS are on the same TRX ).

� an increase of MCS, i.e. of throughput experienced by one TBF, does not lead to an increase of transmission links need since this increase can be compensated by a decrease of MCS experienced by another TBF.

� The GCH left while the control blocks are transferred can also be re-used by other TBFs (which is not the case in B8); indeed control blocks are encoded with CS1 and do not use an entire 320-bit frame.

The Statistical Multiplexing introduces a new segmentation of the radio blocks on the M-EGCH link: the blocks

of all the PDCHs of the TRX are sent one after the other without padding between them. As in B8 a block for a

PDCH can be spread over several 320-bit frames but after its last segment the block of another PDCH can be

started (if the remaining transmission capacity is sufficient). So a fixed 320-bit frame can have up to 2 or 3

segments of variable size. As in B8, the unused part of a 320bit frame (once all the PDCHs have been

scheduled) is filled with padding and the unused GCHs with a NODATA PDU.

The EGCH layer is highly impacted to support the statistical multiplexing and is renamed “M-EGCH layer” in

B9. This feature only applies to G3 and G4 TRX while the G2 DRFU TRX uses a B7.2 like GCH stack (1 GCH

allocated per PDCH to support up to CS2 TBFs).







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2 B9 features


� Statistical multiplexing at M-EGCH layer does increase the BSS PS capacity without running out of Abis/Ater resources.

� Increase of BSC capacity in terms of # of TRXs allows :

� higher PS throughputs

� lower PS blocking/drop probabilities







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2.8 Dynamic Abis allocation

� This feature enables, on the Abis, to dynamically allocate nibbles among the different TREs used for PS traffic in a given BTS. Compared to B8, it allows a higher average Abis bandwidth per PDCH, the BSC capacity in terms of TRXs is increased, and in some BTS configurations it may avoid to deploy a second Abis link. The extra Abis nibbles are shared at BTS level.


� Increase of BSC capacity in terms of # of TRXs handled allows higher PS throughputs and could lead to lower PS blocking/drop probabilities.







1 � 1 � 110

2 B9 features


� Increase of BSC capacity in terms of # of TRXs handled allows higher PS throughputs and could lead to lower PS blocking/drop probabilities.







1 � 1 � 111

2 B9 features

2.9 Enhanced transmission resource management

� Deals with the determination of the number and of the nature of the 16k GCH channels inside each M-EGCH. It is implemented as a transmission resource manager. The transmission resource manageris located at MFS/GPU level. It handles both Abis and Ater resources at GCH level.

� It is in charge of:

� Creating and removing the M-EGCH links

� Selecting, adding, removing, and redistributing GCHs over the M-EGCH links

� Managing transmission resource preemptions

� Managing Abis and/or Ater congestion states,

� Optionally, monitoring M-EGCH links usage, according to the (M)CS of their supported TBFs (UL and DL).

� Abis nibbles sharing rules:

• To ensure that, anytime, each cell of a given BTS would be able to support PS traffic, we should

guarantee a minimal number of Abis nibbles to every cell in the BTS. Consequently, it has been

decided that basic Abis nibbles are only shared at cell level (i.e. among TRXs of the same cell or

sector). This restriction prevents some cells from using the whole Abis nibbles of the BTS as a

given cell cannot use the basic Abis nibbles of another cell. However, Extra (and Bonus) Abis

nibbles are shared at BTS level.

� Ater nibbles sharing rules:

• A given amount of Ater transmission resource is allocated per GPU. Afterwards, this Ater

transmission resource is shared among the four DSPs of the GPU thanks to the GPU on-board Ater

switch.

• Only 64K Ater TS are handled at GPU-level between DSPs. Thus, a 64K Ater TS may be moved

from one DSP to another if, and only if, all its four 16K Ater nibbles are free. This is the unique

restriction to Ater nibbles sharing at GPU-level.

• Furthermore, to prevent the above restriction from disturbing the First GPRS traffic in a cell, an

Ater reserve shall always be available. The Ater reserve consists on one or several free 64K Ater

TSs and is defined per GPU. Every 64K TS of the Ater reserve may be connected to any DSP of the

GPU to fulfil GCH requests:

• to establish the initial GCH in a cell with the Fast Initial GPRS Access feature activated, or;

• to ensure the First GPRS traffic in a cell with no active initial GCH.

• Each time a 64K TS is taken from the Ater reserve, a process is launched to retrieved another 64K

TS to replace it in the Ater reserve. This is done by means of GCH pre-emption on the Best effort

traffic supported by the GPU.







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2.10 RMS_I1 Improvements

� The goal of the feature is to monitor the usage of each allowed AMR codecs (FR or HR), and to provide statistics information on timing advance.

� This feature allows monitoring the proper operation of AMR and the quality of the radio coverage in a cell. It also gives the possibility to tune the AMR parameters. Indeed, statistics about frame erasure rate in uplink and comparison between codec distribution and RXLEV allow assessing the voice quality, and adapting AMR thresholds to the situation of a given cell.

� RMS_I1 Indicators:

Mnemonic Definition Formula

RMS_AMR_FR_UL_BAD Number of bad speech frames using any AMR FR codec in uplink

RMS44a

RMS_AMR_HR_UL_BAD Number of bad speech frames using any AMR HR codec in uplink

RMS45a

RMS_AMR_FR_UL_RXLEV_UL Number of speech frames using one AMR FR codec in uplink per Rxlev on the uplink path

RMS46a

RMS_AMR_HR_UL_RXLEV_UL Number of speech frames using one AMR HR codec in uplink per Rxlev on the uplink path

RMS48a

RMS_AMR_FR_DL_RXLEV_DL Number of speech frames using one AMR FR codec in downlink per Rxlev on the downlink path

RMS47a

RMS_AMR_HR_DL_RXLEV_DL Number of speech frames using one AMR HR codec in downlink per Rxlev on the downlink path

RMS49a







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� Knowing which codecs are the most used, and comparing them with link level in the cell, the operator could assess the voice quality and possibly adapt the AMR parameters (definition of the subset, thresholds and hysteresis).

� These parameters are different for AMR FR and AMR HR, information shall be provided separately for AMR FR and AMR HR.

� The codecs used in UL and in DL can be different; therefore interpretation of results would be easier if results are provided separately for uplink and downlink.







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2.11 RMS_I2 Improvements

� The aim of this feature is to provide statistics information on timing advance, in order to understand geographical traffic distribution in a cell, to identify resurgences and hot spots.

� The improvement “RMS_I2: Timing advance” is a good indicator about the mobile position relative to a cell.

� Its usage in RMS B7.2 is very limited: only measurement reports done over a TA threshold are available, along with the max measured TA. This information is not detailed enough to understand geographical distribution in a cell, in order to identify resurgences and hot spot.

� RM_I2 Indicators:

Mnemonic Definition Formula

RMS_TPR_TIMING_ADVANCE The distribution of number of measurement reports for which the value of timing advance is in TA band

RMS50a

RMS_TPR_UL_RXLEV_TA_BAND

The average value of RXLEV per TA band in uplink.

RMS51

RMS_TPR_DL_RXLEV_TA_BAND

The average value of RXLEV per TA band in downlink.

RMS52

RMS_TPR_UL_RXQUAL_TA_BAND

The average value of RXQUAL per TA band in uplink.

RMS53

RMS_TPR_DL_RXQUAL_TA_BAND

The average value of RXQUAL per TA band in downlink.

RMS54







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2 B9 features


� This RMS improvement described here would provide help to the operator for optimization of his network planning, through identification of these resurgences and hot spots. Detecting hotspots can be very useful in order to re-design that part of the network in a most adapted way to the experienced traffic load.







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3 (E)GPRS Radio Algorithms







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3.1 Cell Reselection Overview

� In GSM, when an MS in idle mode moves from cell A to cell B, it performs a cell reselection applying the C1 or C2 criteria. In dedicated mode, MS performs a handover

� For (E)GPRS, the MS does in GMM READY state (PTM) cell reselection

� In the old cell an abnormal TBF release takes place

� In the new cell the MS establishes a new resource. (Different to handover in GSM, where the new channel is reserved by the network in advance) RA B

RA A

selection

reselection

Cell 1

Cell 2

Cell 3

LA 1

LA 2







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3.1 Cell Reselection Overview [cont.]

� Three modes of cell reselection have been defined for a MS in GPRS packet transfer mode:

� NC0 mode: (E)GPRS MS performs autonomous cell reselection without sending measurement reports to the network

� NC1 mode: (E)GPRS MS performs autonomous cell reselection. Additionally it sends measurement reports to the network

� NC2 mode: (E)GPRS MS shall not perform autonomous cell reselection. It sends measurement reports to the network. The network controls the cell reselection

� B9 release supports NC0 and NC2 modes

� NETWORK_CONTROL_ORDER parameter defines whether the MS or the BSS controls the cell reselections� NC0 mode: NETWORK_CONTROL_ORDER = 0

� NC2 mode: NETWORK_CONTROL_ORDER = 3







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� The attached (E)GPRS mobiles use different criteria, depending on whether the PBCCH is present or not in the serving cell

� No PBCCH in the serving cell:

� GMM standby:� Only NC0 mode is applied. Cell reselection is identical to the basic GSM cell reselection in idle mode.

C1 and C2 criteria are used

� GMM ready:� NC2 mode is applied if set by the Operator. C1NC2, C2NC2 criteria are used

� NC0 mode is applied if NC2 mode is not set and consequently C1, C31 and C32 criteria are used

� PBCCH established in the serving cell:

� GMM standby: � Only NC0 mode is applied. C1, C31 and C32 criteria are used

� GMM ready: � NC2 mode is applied if set by the Operator. C1NC2, C31NC2 and C32NC2 criteria are used

� NC0 mode is applied if NC2 mode is not set and consequently C1, C31 and C32 criteria are used

� In GSM

• C1 = A - Max (0,B) with:

- A = RLA_C - RXLEV_ACCESS_MIN

- B = MS_TXPWR_MAX_CCH - MS_TXPWR_MAX + POWER_OFFSET(1800)

• C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET(T) when Penalty_time<31

• C2 = C1 - CELL_RESELECT_OFFSET when Penalty_Time=31

� In GPRS ready and standby states, cell reselection is performed by the MS except for a class A MS while

in dedicated mode of a circuit switched connection, in which case the cell is determined by the

network according to the handover procedures.

� For a class B MS which can combine GSM and GPRS states, C1 criterion is used when the MS

simultaneously attached to both, the network and the MS is in Packet Idle Mode (refer to GSM 05.08).







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� Independent from the presence of the PBCCH

� The GPRS cell adjacencies

� are the same in packet idle mode as in packet transfer mode

� are set equal to the CS cell adjacencies (i.e. the BA(GPRS)=BA(BCCH) list )

� Recommendation is to enable the GPRS service on all cells in order to prevent a MS to reselect a cell without GPRS support







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3.2 Cell reselection: NC0 mode, no PBCCH established

� The same procedure as in GSM, with the following criteria applied:

� C1: the pathloss criterion, for cell selection and reselection

� C2: for cell reselection

� C1 criterion: the path loss criterion is satisfied if C1 > 0

� C1 = A - Max(B,0)

A = RLA_C - RXLEV_ACCESS_MIN

B = MS_TXPWR_MAX_CCH – P

� RLA_C = Received Level Average for CS service

� RXLEV_ACCESS_MIN = Minimum received signal level at the MS required for access to the system

� MS_TXPWR_MAX_CCH = Maximum TX power level an MS may use when accessing the system

� P = Maximum RF output power of the MS

� The cell n denotes either the serving cell or a neighboring cell.

� In the above equations, the following notations mean:

• AV_RXLEV_NC2(n) is the average received signal level measured by the MS on the BCCH of the cell n.

• RXLEV_ACCESS_MIN(n) or GPRS_RXLEV_ACCESS_MIN(n) is the minimum received signal level required

to perform an access to the cell n.

• MS_TXPWR_MAX_CCH(n) or GPRS_MS_TXPWR_MAX_CCH(n) is the maximum transmit power of the MS

when accessing the cell n.

� P(n) is the maximum output RF power of the MS in the BCCH frequency band of the cell n. P(n) gives

the MS Radio Access Capability Information Element provided in the Packet Resource Request message

or in the DL LLC PDU. In the NC cell reselection procedure, the parameter P(n) shall always refer to the

RF power capability of the GMSK modulation.

� Note that all values are expressed in dBm.

� The cell ranking criterion parameter C2NC2 is used to order the candidate cells on an radio criterion.

This criterion applies only in serving cells where there is no PBCCH established.

• CELL_RESELECT_OFFSET(n) is a positive offset which favors or disfavors the cell n.

• PENALTY_TIME(n) indicates whether the cell reselection offset shall be positive or negative.







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3.2 Cell reselection: NC0 mode, no PBCCH established [cont.]

� C2 criterion:

� PENALTY_TIME <> 11111

C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET * * H(PENALTY_TIME - T) � non-serving cells: H(x) = 0 for x < 0; H(x)= 1 for x ≥ 0

� serving cells: H(x) = 0

� T is a timer implemented for each cell in the list of strongest carriers. T shall be started from zero at the time the cell is placed by the MS on the list of strongest carriers

� CELL_RESELECT_OFFSET may be used to give different priorities to different bands when multiband operation is used

� TEMPORARY_OFFSET applies a negative offset to C2 for the duration of PENALTY_TIME after the timer T has started for that cell.

� PENALTY_TIME = 11111

C2 = C1 - CELL_RESELECT_OFFSET

� If CELL_RESELECT_PARAM_IND = 0 then C2 = C1







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3.3 Cell reselection: NC0 mode, PBCCH established

� The following criteria are applied for cell reselection:

� C1: when C1< 0

� C31, C32: when a non-serving cell is evaluated to be better than the serving cell

� C1: the pathloss criterion � Is used as a minimum signal level criterion for cell reselection for GPRS in the same way as for GSM Idle mode criterion

� Same as defined, but with specific GPRS parameters:

� C1 = A - Max(B,0)

A = RLA_P - GPRS_RXLEV_ACCESS_MIN

B = GPRS_MS_TXPWR_MAX_CCH – P

� GPRS specific parameters, are broadcast on PBCCH of the serving cell







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3.3 Cell reselection: NC0 mode, PBCCH established [cont.]

� C31: the signal level threshold criterion parameter for hierarchical cell structures (HCS)

� Is used to determine whether prioritized hierarchical GPRS and LSA cell re-selection shall apply

� For cells that fulfill C31criteria (C31>0):

� The best cell is the cell with the highest C32 value, among those cells that have the highest priority class, among those cells that have highest LSA priority

� If no cell fulfils the C31 criterion:

� The best cell is the cell with the highest C32 value, among all the neighbor cells

� C32: cell ranking criterion parameter is used to select cells amongthose with the same priority class

� The signal level threshold criterion parameter C31NC2 is used in hierarchical cellular networks to

determine whether the signal level received from a neighboring cell n is sufficient to redirect the MS

towards cell n based on a non-radio priority criterion. This criterion parameter is used only if there is a

PBCCH established in the serving cell. HCS_THR(n) defines a signal threshold for applying the

prioritized hierarchical GPRS cell reselection criterion. The cell n denotes either the serving cell or a

neighboring cell. Contrary to the C31 criterion implemented in the MS, the Alcatel BSS does not

manage the timer T implemented for each cell to monitor the time a neighboring cell is present in the

list of the strongest carriers. Therefore, the Alcatel BSS always assumes that

GPRS_TEMPORARY_OFFSET(n) = 0. As the GPRS_CELL_RESELECT_HYSTERESIS,

RA_RESELECT_HYSTERESIS, and C31_HYST are used to control the triggering conditions of a cell

reselection, they are not taken into account in the criterion C31NC2 and C32NC2 parameters.

� The cell ranking criterion parameter C32NC2 is used to order the candidate cells on an radio criterion.

This criterion applies only in serving cells where there is a PBCCH established.

GPRS_RESELECTION_OFFSET(n) applies a positive or negative offset which favors or disfavors the

neighboring cell n. The cell n denotes either the serving cell or a neighboring cell. If the parameter

C32_QUAL is set, the determination of C32NC2 is modified so that the neighboring cell n having the

highest AV_DL_RXLEV_NC2 among all the neighboring cells is applied a GPRS_RESELECTION_OFFSET

(only if the offset is positive) and no GPRS_RESELECTION_OFFSET is applied to the other neighboring

cells.

� The MFS shall take care of avoiding ping-pong effects between the old cell and the new cell (i.e.,

circular NC cell reselections). For that purpose, the MFS handles an anti-ping-pong timer and an anti

ping-pong offset, respectively called T_NC_PING_PONG and NC_PING_PONG_OFFSET. While the timer

T_NC_PING_PONG is running the neighboring cells are disfavored by the offset NC_PING_PONG_OFFSET

(expressed in dB) in the cell ranking process.

� The MFS starts the anti-ping-pong timer at the creation of the NC2 context for the MS.

� The MFS stops the anti ping-pong timer at the deletion of the NC2 context.







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� C31 criterion

� Serving cell:

C31(s) = RLA_P(s) – GPRS_HCS_THR(s)

� Neighbor cell:

C31(n) =

� RLA_P is the received level average for PS service (i.e. C value)



GPRS_PRIORITY_CLASS(n) <>

GPRS_PRIORITY_CLASS(s)

GPRS_PRIORITY_CLASS(n) =


T(n) <= GPRS_PENALTY_TIME(n) = RLA_P(n) – GPRS_HCS_THR(n) – GPRS_TEMPORARY_OFFSET(n)

= RLA_P(n) - GPRS_HCS_THR(n)

T(n) > GPRS_PENALTY_TIME(n) = RLA_P(n) - GPRS_HCS_THR(n) = RLA_P(n) - GPRS_HCS_THR(n)







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� The following parameters are broadcast on PBCCH of the serving cell:

� GPRS_HCS_THR is the signal threshold for applying HCS GPRS and LSA re-selection

Min: -110 dBm; Max: -48 dBm; Default: -84 dBm

� GPRS_PRIORITY_CLASS is the HCS priority of the cell

Min: 0 (lowest); Max: 7 (highest); Default: 0

� GPRS_PENALTY_TIME is the time during which the GPRS_TEMPORARY_OFFSET is active in neighbour cells

Min: 10s; Max: 320s ; Default: 10s

� GPRS_TEMPORARY_OFFSET applies a negative offset to C31/C32 for the duration of GPRS_PENALTY_TIME after the timer T has started for that cell

Min: 0; Max: infinity (coded 7); Default: 0







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� C32 criterion

� Serving Cell:

C32(s) = C1(s)

� Neighbor cell:

C32(n) =

� GPRS_RESELECTION_OFFSET is used to apply an permanent offset for GPRS cell reselection in neighbor cells

Min: -52 dBm; Max: +48 dBm; Default: 4 dBm



GPRS_PRIORITY_CLASS(n) <>


GPRS_PRIORITY_CLASS(n) =


T(n) <= GPRS_PENALTY_TIME(n) = C1(n) +

GPRS_ RESELECTION_OFFSET(n)

= C1(n) + GPRS_ RESELECTION_OFFSET(n) - GPRS_TEMPORARY_OFFSET(n)

T(n) > GPRS_PENALTY_TIME(n) = C1(n) +

GPRS_ RESELECTION_OFFSET(n) = C1(n) +

GPRS_ RESELECTION_OFFSET(n)

� C1 is the same as in GSM except that

• A = RLA_P – GPRS_RXLEV_ACCESS_MIN: “listening capacity of MS in the cell”

• B = GPRS_MS_TXPWR_MAX_CCH – P: “talking capacity of MS in the cell”

• C1 shall be positive and as high as possible

� C32:

• if C32_QUAL=1, positive GPRS_RESELECTION_OFFSET value shall only be applied to the

neighboring cell with the highest RLA_P value of those cells for which C32 is compared above.

• If GPRS_RESELECTION_OFFSET (neighbor) >0, the cell has a bonus to reselection

• If GPRS_RESELECTION_OFFSET (neighbor) <0, the cell has a handicap for reselection

� In Packet Idle Mode, the MS shall make one measurement for each BCCH carrier monitored every 4

seconds, as well as more than one sample per second for each BCCH carrier.

� A list of 6 strongest cells shall be kept updated at a rate of at least one update per running average

period.

� In Packet Transfer Mode, the MS shall monitor a list of 6 strongest non-serving cell BCCH carriers. It

shall attempt to check the BSIC for each of these 6 strongest cells at least once every 10 seconds.







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� C32 is an improvement of C2. It applies an individual offset and hysteresis value to each pair of cells, as well as the same temporary offsets as for C2.

� Additional hysteresis values apply for a cell re-selection that requires cell or routing area update

� With C32, neighbor cells can be favored through the GPRS_RESELECTION_OFFSET(n) broadcast on the PBCCH. This allows favoring neighbor cells e.g. based on their frequency band

� C32 also gives the possibility to temporarily penalize neighbor cells having the same priority as the serving cell (contrary to C31 that penalizes cells of different priorities). The penalty is computed based on the GPRS_TEMPORARY_OFFSET(n) and GPRS_PENALTY_TIME(n) parameters, like for C31







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� If cell B is belonging to another Routing Area (RA) than cell A, the MS has to make RA update

� additional hysteresis are applied to avoid unnecessary RA updates:

� CELL_RESELECT_HYSTERESIS hysteresis for cell reselection applied on C1 criterion (no PBCCH), when the new cell is in a different LA or, for a GPRS MS, in a different RA, or when a GPRS MS is in GMM ready state

� RA_RESELECT_HYSTERESIS indicates in both STANDBY and READY state the additional hysteresis which applies on C31 and C32 (with PBCCH) when selecting a cell in a new RA

� C31_HYST: Determines whether an additional cell hysteresis shall be applied to the C31 criterion in same RA, in READY state

� GPRS_CELL_RESELECT_HYSTERESIS additional hysteresis







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3.4 Cell reselection execution: NC0 in PTM

� THERE ARE NO HANDOVERS IN GPRS The MS is performing now Cell Reselection during a TBF

� it leaves the coverage area of the cell or enters in a building

� if a neighbor cell is better (from C Criterion point of view), the MS performs a cell re-selection � abnormal TBF release happens

� in the new cell, a new TBF is automatically established, after (P)SI information acquisition

� only the remaining data from the ‘old’ TBF will be sent then automatically

� Coding scheme adaptation is active in parallel and independentlytriggered







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3.4 Cell reselection execution: NC0 in PTM [cont.]

CS 1

CS 2

Throughput

[kbit/s]

Time

[s]t1 t2 t3 t5t4t0

Average

Throughput

Throughput

TBF 1 (Cell 1) TBF 2 (Cell 2)

Data “Call” Duration

1. CS change1. CS change

Cell

Re-Selection

� Typical GPRS data transmission with cell reselection







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3.5 Cell reselection: NC2 mode

� In NC2 mode of operation, the BSS controls the cell reselections of all MS when in packet transfer mode (PTM) or of all MS when in GMM Ready state (depending on the selected NC2 deactivation mode)

� While the NC2 mode is activated for the concerned MS, the MS sends packet measurements reports (PMR) to the BSS

� Aim: NC2 mode is to limit the number of reselections to the strict necessary ones � increased data throughput

� Alcatel NC2 implementation allows to favor GPRS traffic inside GPRS preferred cells (GPRS redirection)

� Particular layer (e.g. macro)

� Particular frequency band (e.g. GSM 900)

� reduced impact on signaling load

� Each time the MS performs a cell reselection, the data transfer is interrupted and a retransmission of

some LLC PDUs may be required:

• The on-going TBF is released in the old cell.

• The MS performs the PSI or SI acquisition in the new cell.

• Then, the MS establishes a new UL TBF in this cell to send a Cell Update message to the SGSN.

• The MFS deletes or reroutes towards the new cell the LLC PDUs stored in the old cell.

- if they are deleted, a retransmission is needed.

• Finally, the data transfer is re-started (after a DL TBF establishment, in case of DL transfer).

� All these steps degrade the data throughput or the page access time perceived by the enduser.







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3.5 Cell reselection: NC2 mode [cont.]

� NC2 activation� An MS transit to NC2 mode when it receives a PACKET MEASUREMENT ORDER message from the BSS, at the beginning of a data transfer. It provides mainly the NC_REPORTING_PERIOD_T which is the reportingperiod of NC measurements sent by the MS while in PTM (default = 0.96s)

� Measurement reporting and processing� MS periodically reports its NC2 measurements on PACCH through a PACKET MEASUREMENT REPORT

� The BSS handles the following measurements:

� UL serving cell: RXQUAL for GPRS TBF and mean BEP for EGPRS TBF

� DL serving cell: RXQUAL for GPRS TBF and mean BEP for EGPRS TBF

� DL serving and neighbor cells: RXLEV measurements of BCCH

� NETWORK_CONTROL_ORDER is a cell parameter tunable at the OMC-R.

� The R97 and R98 MSs are differentiated from the other MSs. Indeed, all the MSs shall support the NC2

mode, however since no network manufacturer has implemented the NC2 mode, the R97 and R98 MSs

may not have been sufficiently tested and therefore there is a risk of interoperability with these MSs.

� The “Packet Measurement Order” message is used to activate and de-activate the NC2 mode of

operation for a given MS.

• Activation

- The “Packet Measurement Order (NC2)” message is sent when:

› establishing the first Downlink TBF of the Packet Transfer Mode or when re-establishing

the DL TBF while T3192 is running and there is not any on-going UL TBF.

› no measurement report has already been received for that MS during its on-going packet

transfer(s) (UL and/or DL).

› the MS has not been forced to operate in NC2 mode by a Packet Cell Change Order

message (during an intra-RA cell reselection).

• De-activation

- The “Packet Measurement Order (RESET)” message is sent at the end of the data transfer, in

case of NC2_DEACTIVATION_MODE = “NC2 deactivation at the end of the packet transfer”.

- When the MS goes back to the STANDBY state, in case of NC2_DEACTIVATION_MODE = “NC2

deactivation at GMM Ready timer expiry”.







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� Cell reselection detection� NC2 reselection are triggered only for EMERGENCY or for POWER BUDGETcauses:

� Cause PT 1: Too low DL received signal level

� Cause PT 2: Detection of a better cell

� Cause PT 3: Too bad DL radio quality

� Cause PT 4: Too bad UL radio quality

� The criteria calculated by the BSS in NC2 mode are very near from those used by the MS in NC0 mode. This ensures that the target cell selected by the MS in NC0 mode or by the BSS in NC2 mode are identical in quite all cases

� C1NC2, C2NC2, C31NC2 and C32NC2 criteria are calculated by the BSS and the parameters defined for cell reselections in NC0 are re-used







1 � 1 � 135



� Cause PT1: Too low DL received signal level� AV_DL_RXLEV_NC2 < NC_DL_RXLEV_THR + Max(BNC2,0)

� NC_DL_RXLEV_THR = -110 dBm (Never) � deactivates Cause PT1

� Cause PT1 is equivalent to check the condition C1NC2 < 0 assuming that the (GPRS_)RXLEV_ACCESS_MIN threshold is replaced by NC_DL_RXLEV_THRthreshold

� C1NC2: Pathloss Criterion parameter

� C1NC2(n) = ANC2(n) – max(BNC2(n),0)

� No PBCCH

ANC2(n) = AV_RXLEV_NC2(n) – RXLEV_ACCESS_MIN(n)

BNC2(n) = MS_TXPWR_MAX_CCH(n) – P(n)

� PBCCH established

ANC2(n) = AV_RXLEV_NC2(n) – GPRS_RXLEV_ACCESS_MIN(n)

BNC2(n) = GPRS_MS_TXPWR_MAX_CCH(n) – P(n)

The cause PT1 is equivalent to check the condition C1NC2 < 0 assuming that the (GPRS_)RXLEV_ACCESS_MIN

threshold is replaced with NC_DL_RXLEV_THR threshold.

Max (Bnc2,0) = handicap on threshold if MS can't reach max UL tx power recommended in the cell







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� Cause PT2: Detection of a better neighbor cell

� AV_DL_RXLEV_NC2 ≤ NC_DL_RXLEV_LIMIT_THR

and

{

No PBCCH:

C2NC2(n) > C2NC2(s) + NC_RESELECT_HYSTERESIS (s,n)

PBCCH established:

C32NC2(n) > C32NC2(s) + NC_RESELECT_HYSTERESIS (s,n)

}

� NC_RESELECT_HYSTERESIS (s,n) defined per cell adjacency link

� NC_DL_RXLEV_LIMIT_THR = -110 dBm (Never) � disables Cause PT2

� The cell n denotes either the serving cell or a neighbor cell

Cause PT2 is checked among the neighboring cells n upon receipt of a Packet Measurement Report message. It

is triggered if the value C2NC2 or C32NC2 of one neighboring cell n exceeds the value C2NC2 or C32NC2 of the

serving cell s by at least the O&M hysteresis NC_RESELECT_HYSTERESIS(s,n) defined per cell adjacency link

(respectively whether or not there is a PBCCH in the serving cell).







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� C2NC2: Cell ranking criterion parameter

� used to order the candidate cells on a radio criterion and applies only in serving cells where there is no PBCCH established

� PENALTY_TIME(n) <> “11111”:

C2NC2(n) = C1NC2(n) + CELL_RESELECT_OFFSET(n)

� PENALTY_TIME(n) = “11111”:

C2NC2(n) = C1NC2(n) – CELL_RESELECT_OFFSET(n)

� CELL_RESELECT_OFFSET(n) is a positive offset which favors or disfavors the cell n

� PENALTY_TIME(n) indicates whether the cell reselection offset shall be positive or negative

� The n denotes either the serving cell or a neighbor cell

Same parameter as GSM Reselection

"11111" = value 31 (or infinity)







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� C31NC2: signal level threshold criterion parameter

� Used in hierarchical networks to determine whether the signal level received from a neighbor cell n is sufficient to redirect the MS towards cell n based on a non-radio priority criterion

� Used only if there is a PBCCH established in the serving cell

� C31NC2(n) = AV_RXLEV_NC2(n) – HCS_THR(n)

� HCS_THR(n) defines a signal threshold for applying the prioritized hierarchical GPRS cell reselection criterion

� The cell n denotes either the serving cell or a neighbor cell







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� C32NC2: cell ranking criterion parameter

� Used to order the candidate cells on a radio criterion

� Applies only in serving cells where there is a PBCCH established

� Cell n is the serving cell:

C32NC2(n) = C1NC2(n)

� Cell n is a neighbor cell:

C32NC2(n) = C1NC2(n) + GPRS_RESELECT_OFFSET(n)

� GPRS_RESELECT_OFFSET(n) applies an positive or negative offset which favors or disfavors the neighbor cell n. Cell n denotes either the serving cell or a neighbor cell







1 � 1 � 140



� Cause PT3: Too bad downlink radio quality

� AV_DL_RXQUAL_NC2 > NC_DL_RXQUAL_THR

� NC_DL_RXQUAL_THR: threshold above which Cause PT3 is triggered due to a too bad RXQUAL in DL (while the MS is in PTM)

Min: 0; Max: 7; Default: 7; step size: 0.1

� NC_DL_RXQUAL_THR = 7 (Never) � deactivates Cause PT3

� Cause PT4: Too bad uplink radio quality

� AV_UL_RXQUAL_NC2 > NC_UL_RXQUAL_THR

� NC_UL_RXQUAL_THR: threshold above which Cause PT4 is triggered due to a too bad RXQUAL in UL (while the MS is in PTM)

Min: 0; Max: 7; Default: 7; step size: 0.1

� NC_UL_RXQUAL_THR = 7 (Never) � deactivates Cause PT4

� Cause PT4

• is checked only for the serving cell whenever one UL RLC data block is correctly received for the on-

going UL TBF provided that T_NC_RXQUAL_VALID seconds have elapsed since the computation of the

first UL samples of the UL TBF.

• T_NC_RXQUAL_VALID aims at not triggering false alarms at the beginning of the TBF and not

triggering an NC cell reselection for a very short TBF.

� Cause PT3

• is checked only for the serving cell each time a (EGPRS) Packet Downlink Ack/Nack message is

received provided that the DL TBF is not in delayed release state and provided that the

T_NC_RXQUAL_VALID seconds have elapsed since the receipt of the first Packet Downlink Ack/Nack

message of the DL TBF.

• T_NC_RXQUAL_VALID aims at not triggering false alarms at the beginning of the TBF and not

triggering an NC cell reselection for a very short TBF.







1 � 1 � 141



� Candidate cell evaluation� Cell Filtering: this process removes from the list candidates the cells to which a previous NC2 cell reselection failed

� Cell Ranking:

� No PBCCH� The cell are ranked to their C2NC2 value. The best cell candidate is the cell having the highest C2NC2 value

� PBCCH established� The cell are ranked based on the C31NC2 and C32NC2 criteria. Among the cells, the best cell is the cell with the highest C32NC2 value among:

o For cells that fulfill C31NC2criterion (C31NC2>0):

Those cells having the highest PRIORITY_CLASS(n)

o If no cell fulfill C31NC2 criterion:

All cells







1 � 1 � 142



� Cell reselection execution� The network triggers the cell reselection by sending a PACKET CELL CHANGE ORDER message

� NC2 deactivation� Two modes via the O&M parameter NC2_DEACTIVATION_MODE:

� NC2 deactivation at the end of packet date transfer

� NC2 deactivation at Ready timer expiry

On-going data transfer (1)

MS Cell A

Packet Measurement Report (2)

Cell B SGSN

(3)Packet Cell Change Order (4)

UL LLC PDU (8)

UL TBF establishment (7)

Flush-LL PDU (9)

Flush-LL-Ack PDU (10)

(6)Packet Control Ack. (5)







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3.6 GPRS redirection

� Thanks to NC2 activation for MS in PTM

� B8/B9 release GPRS redirection is actually a NC cell reselection that is triggered at the beginning of the PTM in the serving cell even if the radio link is good

� Redirect the MS towards a target cell more appropriate to carry PS traffic

� The operator may wish to favor GPRS traffic in a particular layer/band:

� MULTILAYER NETWORK, it may be more efficient to define GPRS resources in the UPPER LAYER only

� Reduce the number of cell reselections

� Microcells have smaller traffic capacity and is assigned to CS







1 � 1 � 144


3.6 GPRS redirection [cont.]

� MULTIBAND NETWORK, it may be more efficient to favor GPRS traffic in the 900 MHz band, due to its better indoor penetration

� MS GPRS mainly used in indoor environment

� Gain in stability of the GPRS session

� Operator must tune the NC parameters so that a NC cell reselection is systematically triggered at the beginning of a data transfer on receipt of the first Packet Measurement Report

� E.g. NC cell reselection Cause PT1 can be always activated by setting NC_DL_RXLEV_THR = - 47 dBm (Always)







1 � 1 � 145


3.7 GPRS Power Control: Overview

� GPRS power control is only implemented in uplink in open loopconfiguration

� GSM recommendation 05.08

� During open loop power control, the MS adapts its output power in UL per block (i.e. 4 timeslots), based on the measured average signal strength in DL

� Open loop:

� There is no indication by the BTS whether the output power was sufficiently low or high: the same path loss in UL and DL is assumed by the MS

� When accessing the network on the (P)RACH the MS uses the outputpower defined by (GPRS_)MS_TXPWR_MAX_CCH, which is broadcasted on the (P)BCCH







1 � 1 � 146


3.8 GPRS Power Control: Measurements

� MS (E)GPRS performs the necessary LEVEL measurements for power control algorithm, either on the BCCH of the serving cell or on the PDCH (carrying the PACCH):

� The choice is made according to PC_MEAS_CHAN parameter, which is broadcasted on the BCCH:

� PC_MEAS_CHAN = 1, measurements on PDCH (default)

� 24 measurements in 480 ms

� PC_MEAS_CHAN = 0, measurements on BCCH

� 12 measurements in 480 ms

� The LEVEL measurements are averaged with recursive filtering algorithms

� The average levels are calculated by the MS in PIM and PTM modes, thus proper average level available at transfer start







1 � 1 � 147


3.8 GPRS Power Control: Measurements [cont.]

� Averaging� Recursive Filtering (in the MS) to obtain average level

� Recursive Filtering Formula:

Cn=a * SSn + (1-a) * Cn-1

� Cn is the DL level average calculated by the MS (Cn-1 =previous value)

� SSn is mean of received signal level of 4 bursts

� a is the forgetting factor

� Packet Idle Mode

a = 1 / [min (n, max (5,T_AVG_W/TDRX) ) ]

� TDRX= parameter which considers the number of measurements that are made and the paging group; TDRX=BS_PA_MFRMS

� BS_PA_MFRMS = number of multiframes needed to send all paging groups

� T_AVG_W = 2k/2 /6 (k=1..25, recommended k < 12) is the signal level filter period for PC in PIM







1 � 1 � 148



[7-10]916

[7-10]914

[6-10]912

[6-10]910

[6-10]88

[6-10]86

[5-9]74

[1-7]42

Range to investigate

Default value of kGSM averaging window size (A_LEV_PC)

� Packet transfer Mode

a = 1/[6* T_AVG_T] on BCCH

a = 1/[12* T_AVG_T] on PDCH

� T_AVG_T= 2k/2 /6 signal level filter period for PC in PTM

� k for T_AVG_T for measurements on BCCH or on PDCH:







1 � 1 � 149



20

25

30

35

40

45

50

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 121 126 131 136 141

RXLEV_DL GSM average practical GPRS average

� Averaging� Tuning of k: average mechanism convergent between GSM and GPRS

� Comparison between GSM averaging and the practical GPRS averaging with A_LEV_PC=2 and K =4:







1 � 1 � 150

� Each block is transmitted by the MS with the output power PCH:

PCH=min (Γ0 - ΓCH - α * (C+48), (GPRS)MS_TXPWR_MAX_CCH))

� Γ0 : is the maximum classmark power of the MS

� = 39 dBm in GSM 900/850/400

� = 36 dBm in GSM 1800/1900

� ΓCH : is sent to the MS. This parameter is used for grading the power control to a target received level at the BTS side

� Min:0; Max: 62; Default: 30 dB in GSM 900, 24 dB in GSM 1800

� α : is send to the MS. This parameter can be described as a reactivity factor. The 05.08 GSM recommendation suggest to use α = 1 in order to have an open loop power control

� C : is the DL level average calculated by the MS


3.9 GPRS Power Control: Algorithm







1 � 1 � 151


3.9 GPRS Power Control: Algorithm [cont.]

� Tuning of ΓCH and α

� Idea: Tune PC algorithm to balance DL and UL paths

� α

�α = 1 (according to GSM 05.08)

� ΓCH� tune ΓCH in order to reach the Minimum UL Level (RXLEVUL) at the BTS

� ΓCH = Γ0 - 48 - RXLEVUL - PBTS

� Balanced DL and UL paths:

� PMS - RXLEVUL = PBTS – RXLEVDL

� PBTS : BTS power; PMS: MS power

� RXLEVUL: Received level at BTS side

� RXLEVDL: Received level at MS side (C value in the PC formula)







1 � 1 � 152


3.9 GPRS Power Control: Algorithm [cont.]

� Example: Tuning of ΓCH and α

� Settings:

� MS_Power_MAX = 33 dBm

� PBTS after connector = 40 dBm

� α

� α = 1

� ΓCH

� tune ΓCH in order to reach the Minimum RXLEVUL at the BTS side

� assume RXLEVUL = - 80 dBm

� ΓCH = Γ0 - 48 - RXLEVUL - PBTS� ΓCH = 33 - 48 - (-80) - 40 = 25 dBm







1 � 1 � 153


3.10 Link adaptation: DL GPRS Radio Link Control

� It relies on RXQUAL except between CS3 and CS4 adaptation, wherethe new metric I_LEVEL_TNi (interference level) is also considered� If CS-4 is used, the MS is allowed to report RXQUAL = 7

� AV_RXQUAL_ST (Short Term average), AV_RXQUAL_LT (Long Term average) and AV_SIR (Signal to Interference Ratio) are respectively averaged values at MFS side, of the RXQUAL and I_LEVEL_TNimeasurements received from the MS in Packet DL Ack/Nackmessages

� AV_RXQUAL_ST

� Triggering condition AV_RXQual_ST aim to decrease the coding scheme number as fast as possible when the radio conditions degraded significantly. Reaction would be much slower if it was only based on a long-term average, which could results in a TBF release







1 � 1 � 154


3.10 Link adaptation: DL GPRS Radio Link Control [cont.]

O&M threshold

and hysteresis

new CS

current CS

- AV_RXQUAL_ST

- AV_RXQUAL_LT

- AV_SIR

MS MFS

(RXQUAL, I_Level_TNi)

Packet DL Ack/Nack

(RXQUAL, I_Level_TNi)

Packet DL Ack/Nack

Averaging

Link

adaptation

� Interference measurements performed during idle frames of the 52 multiframe (twice during 240ms):

� I_LEVEL_TN 0 = I > C

� I_LEVEL_TN 1 = C - 2dB < I ≤ C

� I_LEVEL_TN 2 = C - 4dB < I ≤ C - 2dB


...


� I_LEVEL_TN 15 = I ≤ C - 28dB

� MFS uses the I_LEVEL_TNi received to calculate the AV_SIR value

� In case of DL GPRS TBF with PDCH allocated on BCCH TRX and no frequency hopping on the BCCH TRX, the MS does not report any interference levels � usage of BLER (Block Erasure Rate) instead of interference levels

� Drawback of putting GPRS on BCCH freq : no measure of interference levels







1 � 1 � 155



Current CS

CSi -> CSi+1 CSi -> CSi-1

CS1 AV_RXQUAL_LT < CS_QUAL_DL_1_2 -

CS2 AV_RXQUAL_LT < CS_QUAL_DL_2_3

AV_RXQUAL_LT > CS_QUAL_DL_1_2 + CS_HST_DL_LT

OR

AV_RXQUAL_ST > CS_QUAL_DL_1_2 + CS_HST_DL_ST

CS3

AV_RXQUAL_LT < CS_QUAL_DL_3_4

AND

AV_SIR > CS_SIR_DL_3_4

(CS3_BLER < CS_BLER_DL_3_4)

AV_RXQUAL_LT > CS_QUAL_DL_2_3 + CS_HST_DL_LT

OR

AV_RXQUAL_ST > CS_QUAL_DL_2_3 + CS_HST_DL_ST

CS4 - AV_SIR < CS_SIR_DL_3_4 + CS_SIR_HST_DL

(CS4_BLER > CS_BLER_DL_4_3)

� Coding Scheme changing decision for a downlink GPRS TBF:

� As it has been observed (in the Alcatel labs during the B8 release validation) that some MS do not

report any interference measurements when the BCCH carrier is included in the frequency hopping

sequence of the allocated PDCH, the algorithm described above is slightly modified in the MR2 version

of the B8 release.

� A new triggering condition is used for the CS change between CS3 and CS4. This new triggering

condition shall be applied only to the TBF that do not report any interference level measurements.

Each time a Packet DL Ack/Nack message is received:

• either it contains no interference measurements and the new algorithm is applied,

• or it contains interference measurements and the standard algorithm is applied.

� With the new algorithm, the interference level is replaced by the BLER (RLC BLock Error Rate):

• the CS3 BLER is used for a CS change from CS3 to CS4,

• the CS4 BLER is used for a CS change from CS4 to CS3.

� Remarks :

• case of a DL TBF with PDCH allocated on the BCCH TRX and no frequency hopping on the BCCH

TRX : the MS does not report any interference level measurements in the Packet DL Ack/Nack

message (no interference measurements on the BCCH carrier),

• case of a DL TBF with PDCH having the BCCH carrier belonging to the frequency hopping

sequence : depending on MS implementation, some MS may not report any interference

measurements (behavior observed in the Alcatel labs during the B8 release validation).







1 � 1 � 156



AV_RXQUAL_LT

AV_SIR

CS1

CS2

CS3 CS4

CS_QUAL_DL_1_2 + CS_HST_DL_LT

CS_QUAL_DL_1_2

CS_QUAL_DL_2_3

C S_QUAL_DL_3_4

0

7

0 15 CS_SIR_DL_4_3 CS_SIR_DL_3_4

CS1 or CS2 (hysteresis)


CS3

or

CS4

CS_QUAL_DL_2_3 + CS_HST_DL_LT

� CS_HST_DL_LT and CS_HST_DL_ST are introduced to have hysteresismechanisms, to avoid ping-pong effects between coding schemes:

� The change from CS-3 to CS-4 is not only based on AV_RXQUAL_LT for the two following reasons:

• RXQUAL range only goes down to 0.2%. However, the change of the coding scheme from CS-3 to CS-4

will probably have to be done for even lower values. Indeed, when the coding scheme is CS-4, in

static (AWGN), a BLER of 0.1 (typical value of the BLER threshold to change from CS-3 to CS-4) is

obtained for a raw BER of 1-(1-0.1)1/456 = 2.10-4. This raw BER would be larger in multipath

channels but is likely to remain below 0.2%. This means that CS_QUAL_DL_3_4 should be close to 0

and that a condition based on RXQUAL is not sufficient to change the coding scheme from CS-3 to CS-

4.

• If the changes from CS-3 to CS-4 and from CS-4 to CS-3 are based on different metrics, a Ping-Pong

effect may occur. Indeed, it may happen that the conditions to change from CS-3 to CS-4 and CS-4 to

CS-3 are simultaneously true in some situations.







1 � 1 � 157


3.11 Link adaptation: UL GPRS Radio Link Control

O&M threshold

and hysteresis

new CS

current CS

- AV_RXQUAL_ST

- AV_RXQUAL_LT

UL RLC block

Averaging

Link

adaptation

MS MFS BTS

RXQUAL

measurement

UL RLC block (RXQUAL)

UL RLC block (RXQUAL) � It is based only on RXQUAL,

measured by the BTS

� Interference measurements are not reported by the BTS to the MFS

� AV_RXQUAL_ST (Short Term average), AV_RXQUAL_LT (Long Term average) are averaged values of the RXQUAL received from the BTS







1 � 1 � 158


3.11 Link adaptation: UL GPRS Radio Link Control [cont.]

Current CS CSi -> CSi+1 CSi -> CSi-1

CS1 AV_RXQUAL_LT < CS_QUAL_UL_1_2 -

CS2 AV_RXQUAL_LT < CS_QUAL_UL_2_3

AV_RXQUAL_LT > CS_QUAL_UL_1_2 + CS_HST_UL_LT

OR

AV_RXQUAL_ST > CS_QUAL_UL_1_2 + CS_HST_UL_ST

CS3 AV_RXQUAL_LT < CS_QUAL_UL_3_4


OR


CS4 -


OR


� Coding Scheme changing decision for uplink GPRS TBF:

� AV_RXQUAL_ST is a short term average whereas AV_RXQUAL_LT is a long term average. The short term

average is used to react quickly in case of fast degradation of the radio conditions.

• X = FH or NFH: two thresholds are available for hopping and non-hopping TRXs.

• Y = ACK or NACK: two thresholds are available for RLC acknowledged and unacknowledged modes.

� The thresholds should be chosen so that:

• CS_HST_UL_ST > CS_HST_UL_LT > 0







1 � 1 � 159


3.11 Link adaptation: UL GPRS Radio Link Control [cont.]

AV_RXQUAL_LT

AV_SIR

CS1

CS2

CS_QUAL_UL_1_2 + CS_HST_UL_LT

CS_QUAL_UL_1_2

CS_QUAL_UL_2_3

0

7

0 15



CS3

CS4

CS3 or CS4 (hysteresis) CS_QUAL_UL_3_4



� CS_HST_UL_LT and CS_HST_UL_ST are introduced to have hysteresis mechanisms, to avoid ping-pong effects between coding schemes:

In the uplink, the RXQUAL is available in CS-4 and the SIR measurements are not reported by the BTS to the

MFS so far. Therefore, it is possible to also use RXQUAL measurements to change the coding scheme from CS-3

to CS-4 or from CS-4 to CS-3, contrary to the downlink algorithm, where the SIR was used.







1 � 1 � 160

� Two new metrics are introduced in EGPRS, Mean_BEP (mean Bit error Probability) and CV_BEP (Coefficient of Variation of BEP), to offset the fact that RXQUAL, does not provide an accurate estimation of the bit error rate of the radio channel

� BEP measured on burst basis, is a reflection of the current C/I, time dispersion of the signal and the velocity of the terminal

� The variation of BEP value over several bursts also provides additional information regarding velocity and frequency hopping

� The mechanism is more efficient than in GPRS, since measurements are taken on

every burst and not only during the idle frames


3.12 Link adaptation in EGPRS: New metrics

∑=

=4

1iiburstblock BEP

4

1MEAN_BEP

∑

∑ ∑

=

= =

−

=4

1iiburst

24

1k

4

1iiburstkburst

block

BEP4

1

BEP4

1BEP

3

1

CV_BEP

�For more details about MEAN_BEP and CV_BEP averages performed by the MS, refer to 3GPP 05.08.

�Raw measurements on a radio block basis

• For EGPRS (that is during an EGPRS DL TBF), the MS shall calculate the following values, for each radio block (1

radio block = 4 bursts) addressed to it (the DL TBF TFI contained in the radio block must be decoded) :

• Mean Bit Error Probability (BEP) of a radio block:

• Coefficient of variation of the Bit Error Probability of a radio block:

• In the above equations, the BEP is measured on a burst basis by the MS before channel decoding.

� Averaging of the raw measurements on a TS basis

•The raw measurements made by the MS on a radio block basis are averaged by the MS per TS (TN in the below

equations) and per modulation type (GMSK (MCS1 to MCS4), 8-PSK (MCS5 to MCS9)) as follows:

•

•

• with (Rn gives the reliability of the averaged quality parameters)

� In the above equations :

• n is the iteration index, incremented for each DL radio block,

• e is a forgetting factor and is calculated according to the BEP_PERIOD cell parameter (new in B8, OMC-R

changeable),

SEE NEXT SLIDE

∑=

=4

14

1_

i

iburstblockBEPBEPMEAN

∑

∑ ∑

=

= =

−

=4

1

24

1

4

1

4

1

4

1

3

1

_

i

iburst

k i

iburstkburst

block

BEP

BEPBEP

BEPCV

nblock,n

n1n

n

nn MEAN_BEP

R

xeNMEAN_BEP_T)

R

xe(1NMEAN_BEP_T ⋅⋅+⋅⋅−= −

nblock,

n

n1n

n

nn CV_BEP

R

xeCV_BEP_TN)

R

xe(1CV_BEP_TN ⋅⋅+⋅⋅−= −

0R ,xeRe)(1R 1n1nn =⋅+⋅−= −−







1 � 1 � 161


3.13 Link adaptation: DL EGPRS Radio Link Control

Average Power

Decrease in 8-PSK IR

link adaptation

tables

new CS

current CS

MS MFS

(Mean_BEP, CV_BEP)

EGPRS Packet DL Ack/Nack

Link

adaptation

Decision tables are differentdepending on whether the Incremental Redundancy is activated or not

� The link adaptation is based in DL on Mean_BEP and CV_BEPmeasurements reported by the MS in every EGPRS Packet DL Ack/Nackmessage

� The MS can report 32 different Mean_BEP values (0..31) and 8 different CV_BEP values (0..7), per modulation type

� xn denotes the existence of quality parameters for the nth block, i.e. if the radio block is intended for this MS. xn values 1

and 0 denote the existence and absence of quality parameters, respectively

� Measurements reporting

• A MS shall report the overall MEAN_BEP and CV_BEP (instead of reporting the RXQUAL and SIGN_VAR values) per

modulation type (that is GMSK_MEAN_BEP, GMSK_CV_BEP and/or 8-PSK_MEAN_BEP, 8-PSK_CV_BEP depending on the

received blocks since the last channel quality report sent to the network) averaged over all allocated channels

(timeslots) as follows:

• ,

•where n is the iteration index at reporting time and j the TS number.

• The MS reports the Mean_BEP and CV_BEP values to the MFS in the Channel Quality Report included in the EGPRS

Packet DL Ack/Nack and Packet Resource Request messages.

•The MS can report 32 different Mean_BEP values (MEAN_BEP_0 to MEAN_BEP_31). The mapping between the

calculated Mean_BEP value (linear scale) and the reported Mean_BEP value (logarithmic scale) depends on the used

modulation (two mapping tables are given in the 05.08 GSM recommendation : one for GMSK and one for 8-PSK).

•The MS can report 8 different CV_BEP values (CV_BEP_0 to CV_BEP_7). The mapping between the calculated and

the reported values is identical for the GMSK and 8-PSK modulations.

� Measurements and reporting at BTS side

•The BTS measures for each UL burst the BEP and calculates for each UL radio block (4 bursts) the Mean_BEP and the

CV_BEP = Std_BEP / Mean_BEP. The Mean_BEP and the CV_BEP are reported on a radio block basis by the BTS to the

MFS.

∑

∑ ⋅

=

j

(j)

n

j

(j)

n

(j)

n

nR

NMEAN_BEP_TR

MEAN_BEP







1 � 1 � 162


3.13 Link adaptation: DL EGPRS Radio Link Control [cont.]

UL RLC block (CV_BEP, Mean_BEP)

new CS

current CS

UL RLC block

Averaging

Link

adaptation

MS MFS BTS

CV_BEP, Mean_BEP

computation

UL RLC block (CV_BEP, Mean_BEP)

Average Power

Decrease in 8-PSK IR

link adaptation

tables

� In the UL, Mean_BEP and CV_BEP are computed in the BTS and sent to the MFS, in each radio block

� The MFS averages Mean_BEP and CV_BEP and then, a decision can be taken on the link adaptation







1 � 1 � 163


3.14 EGPRS Link Adaptation Decision

� The MFS verify if a MCS change is needed each time it receives new MEAN_BEP and CV_BEP measurements, based on the following algorithm:

IR activated

?

GMSK / 8-PSK

?

APD value

GMSK tables 8-PSK tables

MCS 1..4 MCS 5..9

GMSK / 8-PSK

?

APD value

GMSK tables 8-PSK tables

MCS 1..4 MCS 5..9

RLC Acknowledge Mode

YES NO

GMSK 8-PSK 8-PSKGMSK







1 � 1 � 164


3.15 TRX ranking/TRX transmission pool set-up

TRX <--> TRX transmission pool

ordered list of TRXs

for PS traffic

TRX <--> TRE

TRX ranking

for PS traffic

TRX transmission

pool set-up

TRX characteristics

TRX transmission pools

� TRX ranking� PS capable TRXs (TRX_PREF_MARK = 0) are

ranked at BSC side for PS traffic (from the highest to the lowest), according to the following criteria :

� TRX supporting the BCCH, if PS_Pref_BCCH_TRX = 0

� TRX capability (EGPRS capable High Power, then EGPRS capable Medium Power and finally non-EGPRS capable)

� Dual Rate capability (FR, then DR)

� Size of the PDCH-group

� This ranking will be used in the reverse order for CS traffic

� TRX transmission pool set-up� A TRX transmission pool groups, together extra Abis nibbles for one TRX

� The biggest TRX transmission pools are allocated to the TRXs having the highest ranking for PS traffic.

p.90 et p.91







1 � 1 � 165

� Example:� 5 TREs in a cell

� 1 G4-HP TRE

� 2 G4-MP TREs

� 2 G3 TREs

� PS_Pref_BCCH_TRX = 0 (no specific preference)

� 5 TRXs� TRXa, TRXb, TRXc, TRXd: TRX_PREF_MARK = 0 (PS capable)

� TRXe: TRX_PREF_MARK > 0 (non PS capable)

� 3 DR TRXs

� Pool types

� 1 “type 4”

� 1 “type 2”

� 2 “type 1”


3.15 TRX ranking/TRX transmission pool set-up [cont.]

TREs

Dual Rate usage

associated TRXs

PS capable TRX ranking

associated transmission

pool G4 - HP FR TRXa 1 type 4

G4 - MP FR TRXb 2 type 2

G4 - MP DR TRXc 3 type 1

G3 DR TRXd 4 type 1

G3 DR TRXe







1 � 1 � 166

� For GPRS: the max CS configured (MAX_GPRS_CS)

� For EGPRS:� TRX type (n=1 to 5), received from BSC

� Hardware PS capability of each TRX, received from the BSC

� En_EGPRS (parameter to allow or not EGPRS in the cell), received from the BSC

� Max_GPRS_CS (parameter which gives the highest usable CS in the cell), received from the BSC

� Max_EGPRS_MCS (parameter which gives the highest usable MCS in the cell)


3.16 TRX capability for PS traffic

Max_EGPRS_MCS

O&M

GPRS capability

(CS2/CS3/CS4)

Max_GPRS_CS

TRX GPRS

capability

- HW PS capability - TRX type

BSC

EGPRS capability

(MCS 1-MCS 9)

En_EGPRS

TRX EGPRS

capability

� TRX capabilities are determined at MFS side, taking into account:

p.119







1 � 1 � 167


3.17 Radio Resource Allocation: Overview

� To offer high throughput to EGPRS MSs :� EGPRS TBFs are preferentially allocated on high class TRXs

� Multiplexing, on the same PDCH, a DL EGPRS TBF with an UL GPRS TBF has to be avoided, since in this case, the DL EGPRS is limited to GMSK (i.e. MCS4) � new PDCH state: “EGPRS”

� To fairly share throughput between EGPRS TBFs:

� A higher number of EGPRS TBFs has to be piled up on high class TRXsthan on low class TRXs. This ratio has to take into account the maximum throughput which can be offered by each class of TRX� specific TRX selection for EGPRS TBFs

� To optimize GPRS throughput (i.e. high class TRX usage), as long as it does not conflict with EGPRS traffic

� A new reallocation trigger (T4) is created in order to reallocate an UL GPRS TBF which is multiplexed with a DL EGPRS TBF







1 � 1 � 168


3.18 Radio Resource Allocation: PDCH state

� All the following PDCH states are related to establish TBFs:

� Allocated : The PDCH is a slave PDCH, which has been indicated as usable for PS traffic by the BSC

� Active : An allocated PDCH is active if it supports at least one radio resource allocated for a TBF or for a RT PFC

� Full : � For GPRS TBF:

The number of established TBFs (GPRS + EGPRS TBFs) is equal to MAX_UL/DL_TBF_SPDCH.

� For EGPRS TBF:

The number of established EGPRS TBFs is equal to MAX_UL/DL_TBF_SPDCH.

� EGPRS : SPDCH used in the DL direction by a 8-PSK capable EGPRS TBF. This state is meaningful only for non-EGPRS capable MSs and only in the UL direction.

!!! New states in B9 !!!

Full : for GPRS TBF : GPRS + EGPRS ts are counted, because some EGPRS TBF on GPRS PDCH are using GMSK

MCS.







1 � 1 � 169


3.18 Radio Resource Allocation: PDCH state [cont.]

� New state for GPRS PDCH

� PDCH used in DL direction by 8-PSK capable EGPRS TBF, i.e PDCH does not belong to a class 1 TRX

� meaningful only

� for non-EGPRS capable MS

� only in UL direction

� When meaningful, it overwrites “active” and “busy” states but not the “full” state

� Avoids multiplexing of UL GPRS TBF and DL EGPRS TBF, in order to not reduce the EGPRS throughput







1 � 1 � 170


3.18 Radio Resource Allocation: PDCH state [cont.]

MAX_DL_TBF_SPDCH

FullActiveAllocated

DOWNLINK

MAX_UL_TBF_SPDCH

FullActiveAllocated

UPLINK

[EGPRS] [EGPRS]

One SPDCH has one state per direction (i.e., one state for the UL, one state for the DL). This state depends on the type of the MSs (EGPRS

capable or non-EGPRS capable) for which the radio resource (re)-allocation algorithm is called.

� radio resource allocated to the MFS, but associated transmission resources are not allocated (i.e., the PDCH is not established).

All the following states are related to established PDCHs:

� empty:

• the PDCH is established, but no established TBF.

� active:

• For GPRS TBF: at least one established TBF and the number of established TBFs (GPRS + EGPRS) is smaller than

N_TBF_PER_SPDCH.

• For EGPRS TBF: at least one established EGPRS TBF and the number of EGPRS TBFs (1) is smaller than N_TBF_PER_SPDCH.

� busy:

• For GPRS TBF: the number of established TBFs (GPRS and EGPRS TBFs) is greater or equal to N_TBF_PER_SPDCH, but smaller

than MAX_UL_TBF_SPDCH/MAX_DL_TBF_SPDCH.

• For EGPRS TBF: the number of established EGPRS TBFs (1) is greater or equal to N_TBF_PER_SPDCH, but smaller than

MAX_UL_TBF_SPDCH/MAX_DL_TBF_SPDCH.

� full:

• For GPRS TBF: the number of established TBFs (GPRS + EGPRS TBFs) is equal to MAX_UL_TBF_SPDCH/MAX_DL_TBF_SPDCH.

• For EGPRS TBF: the number of established EGPRS TBFs (3) is equal to MAX_UL_TBF_SPDCH/MAX_DL_TBF_SPDCH.

� EGPRS (2)

• PDCH used in the DL direction by an 8-PSK capable EGPRS TBF (i.e., the PDCH does not belong to a class 1 TRX).

• This state is meaningful only for non-EGPRS capable MSs and only in the UL direction.

• When meaningful, it overwrites “active” and “busy” states (but not the “full” state).

� (1): Only EGPRS TBFs are taken into account to avoid to establish EGPRS TBFs on PDCHs with a low EGPRS capability, because of

GPRS TBFs.

� (2): The aim of this new state is to avoid multiplexing UL GPRS TBF and DL EGPRS TBF, in order not to reduce EGPRS throughput.

� (3): Only EGPRS TBFs are taken into account to avoid radio resource allocation failure because of the restricted list of EGPRS

capable TRXs.







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3.19 TRX selection for EGPRS TBFs

� Specific conditions are defined for TRX selection in case of allocation or reallocation for EGPRS capable MS

� To allocate EGPRS TBFs preferentially on TRX which allows a high throughput

� Principle:

� As long as the TRXs with the highest throughput do not support a maximum number of EGPRS TBFs, the other EGPRS capable TRXs are not taken into account by the algorithm







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3.19 TRX selection for EGPRS TBFs [cont.]

� Following internal variables are defined:

� N_TRX_EGPRS : number of TRXs on which EGPRS MSs are served in EGPRS mode

� MAX_TBF_PDCH_Current(TRXi) : maximum number of EGPRS TBFs per PDCH, currently allocated in TRXi

� N_TBF_PDCH_MCSi_MCSj

� It defines for each EGPRS TRX capability (MCSi) in the cell the number of EGPRS TBFs per PDCH beyond which it becomes more interesting to serve upcoming EGPRS MSs on TRXs with a lower EGPRS capability (MCSj).

� Max_PDCH_Throughput_MCSi / Max_PDCH_Throughput_MCSjwith Max_PDCH_Throughput_MCSx is the maximum theoretical throughput that can be achieved at RLC/MAC per PDCH using MCSx encoding







1 � 1 � 173



EGPRS TRX capability (MCSi)

Immediately lower TRX capability (MCSj)

N_TBF_PDCH_MCSi_MCSj

MCS3 MCS2 1

MCS4 MCS2 1

MCS5 MCS2 2

MCS6 MCS5 1

MCS2 2

MCS6 1

MCS7 MCS5 2

MCS2 4

MCS6 1

MCS8 MCS5 2

MCS2 4

MCS8 1

MCS9 MCS6 2

MCS5 2

MCS2 5

� All the values between MCS2 and MCS9 are possible because of theO&M parameter Max_EGPRS_MCS

� Different used thresholds :

N_TBF_PDCH_MCSi_MCSj are internal parameters which define for each EGPRS TRX capability, in the cell, the

number of EGPRS TBFs per PDCH beyond which it becomes more interesting to serve upcoming EGPRS MSs on

TRXs with a lower EGPRS capability.

This value depends on the throughput gap between 2 consecutive TRXs inside the ordered (according to TRX

Rank) list of EGPRS capable TRXs.

N_TBF_PDCH_MCSi_MCSj = Max_PDCH_Throughput_MCSi DIV Max_PDCH_Throughput_MCSj

� Max_PDCH_Throughput_MCSx is the maximum theoretical throughput that can be achieved at RLC/MAC

per PDCH using MCSx encoding.







1 � 1 � 174



� Example� Assuming that in a cell the following TRXs are EGPRS capable:

� TRXa: EGPRS capability = MCS9

� TRXb: EGPRS capability = MCS5

� TRXc: EGPRS capability = MCS5

� TRXd: EGPRS capability = MCS2

� TRXe: EGPRS capability = MCS2

� Two thresholds are used :

� N_TBF_PDCH_MCS9_MCS5 = 2

� N_TBF_PDCH_MCS5_MCS2 = 2







1 � 1 � 175



CELL START

TRXa

MAX_TBF_PDCH_Current (TRXi) = 0(with i = a, b, c, d or e )

MAX_TBF_PDCH_Current (TRXa) < N_TBF_PDCH_MCS9_MCS5

MAX_TBF_PDCH_Current (TRXb) < N_TBF_PDCH_MCS5_MCS2 _

ORMAX_TBF_PDCH_Current (TRXc) < N_TBF_PDCH_MCS5_MCS2 _

TRXa, TRXb, TRXc

MAX_TBF_PDCH_Current (TRXa) = N_TBF_PDCH_MCS9_MCS5

TRXa, TRXb, TRXc, TRXd, TRXe

MAX_TBF_PDCH_Current (TRXb) = N_TBF_PDCH_MCS5_MCS2 _

ANDMAX_TBF_PDCH_Current (TRXc) = N_TBF_PDCH_MCS5_MCS2 _

MAX_TBF_PDCH_Current (TRXa) < N_TBF_PDCH_MCS9_MCS5

MAX_TBF_PDCH_Current (TRXb) < N_TBF_PDCH_MCS5_MCS2 _

ORMAX_TBF_PDCH_Current (TRXc) < N_TBF_PDCH_MCS5_MCS2 _







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3.20 Radio Resource Allocation: GPRS/EGPRS TBFs

α. If it is not a T3 reallocation �� TRXs for which have already enough GCHs established on the M-EGCH link

A. Lowest number of PDCHs in the “EGPRS” state

B. Highest available throughput in the direction of the bias

C. Highest available throughput in the direction opposite to the bias

D. TRX with the highest priority

E. For EGPRS Best Effort TBFs establishments � Lowest number of GPRS TBFs in the direction of the bias

F. Combination with the PDCHs that have the lowest index.

HIGHHIGH

LOWLOW

IMPORTANCE

!!! New in B9 !!!







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3.20 Radio Resource Allocation: EGPRS TBFs [cont.]

E) The candidate timeslot allocations which have the lowest numberof established EGPRS TBFs in the direction of the bias are preferred � It is preferred to multiplex an EGPRS TBF with a GPRS TBF, rather than with another EGPRS TBF

F) The candidate timeslot allocations which have the lowest numberof established EGPRS TBFs in the direction opposite to the bias are preferred

G) The candidate timeslot allocations which are on a TRX with highest priority are preferred

H) The candidate timeslot allocations which have the lowest numberof established GPRS TBFs in the direction of the bias are preferred � H has a lowest priority than G, in order to avoid to establish EGPRS TBFs on low class TRXs, because of GPRS TBFs

HIGHHIGH

LOWLOW

IMPORTANCE







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3.20 Radio Resource Allocation: EGPRS TBFs [cont.]

I) The candidate timeslot allocations which have all their PDCHsestablished are preferred. If all the preferred best candidate timeslot allocations require additional PDCHs, then a request is sent to the BSC and the algorithm is stopped

J) If the MS has already one or 2 TBFs established, preference is given to the candidate timeslot allocation which does not require a T2 reallocation of the on-going TBFs

K) The candidate timeslot allocation with the PDCHs that have the lowest index is preferred

HIGHHIGH

LOWLOW

IMPORTANCE







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3.21 Radio Resource Allocation: TBF Re-allocation

� B8/B9 release: 4 types of TBF reallocations:

� T1: re-allocation to

�maintain a TBF alive despite a pre-emption on a PACCH of a TBF

� or if MEGCH becomes too low to provide MAX MCS of the TBF [B9]

� T2: re-allocation of an on-going TBF when establishing a concurrent TBF� in order to provide a better throughput

� T3: re-allocation to offer a better throughput to an on-going TBFs� In order to provide a higher throughput, if it is possible, to any TBF in the cell.

� T4: re-allocation condition to move

� UL GPRS TBF sharing one PDCH with a DL EGPRS TBF

� � PDCHs which do not carry a DL EGPRS TBF

B9 : Same types as in B8, but extended possibilities

T2 : It is the case in the following scenarios:

- establishment of a downlink TBF, concurrent to an existing uplink TBF, which is

allocated in such a way that the maximum number of timeslots supported in the

direction of the bias cannot be offered to the MS.

- similar situation in case of uplink TBF establishment concurrent to a downlink TBF;







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3.22 Radio Resource Allocation: Min_PDCH

� Min_PDCH: O&M parameter per cell� Minimum number of PDCHs that are always allocated to the MFS.

� B8/B9 release: Min_PDCH takes into account:� The pre-allocated SPDCH but not established (w/o GCH resource)

� The SPDCH pre-allocated and established for the “fast initial (E)GPRS access”

� The MPDCH represented by the parameter Nb_TS_MPDCH

� Thus, the initial allocation process takes into consideration:

� IF EN_FAST_INITIAL_GPRS_ACCESS = 0 (false)

� MIN_PDCH - Nb_TS_MPDCH SPDCH are requested to the BSC and pre-allocated on the TRX with the highest priority

� IF EN_FAST_INITIAL_GPRS_ACCESS = 1 (true)

� MIN_PDCH - Nb_TS_MPDCH - 1 SPDCH are requested to the BSC and pre-allocated on the TRX with the highest priority







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3.23 Radio Resource Allocation: Fast initial (E)GPRS access

� Also called : “Immediate UL TBF establishment”

� To provide always one established PDCH, usable for UL GPRS and UL EGPRS TBFs, even if there is no PS traffic at all

� A TBF can be immediately established without requesting transmission resource connection to the BSC

� EN_FAST_INITIAL_GPRS_ACCESS, parameter per cell

� flag to indicate whether or not one Slave PDCH for (E)GPRS traffic usage will be statically established in the cell

� Min: 0; Max: 1; Default 0







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4 General (E)GPRS planning principels







1 � 1 � 183

4 General (E)GPRS planning principles

4.1 Throughput Dependency -> Interference (and Level)

Note: the throughput values are ETSI requirements, the C/I values are valid for TU3, SFH enabled

CS-2

CS-1

RL/MAC net

Data Throughput

(kbit/s)12

8

10.8

7.2

C/I = 9 dB

Level of interfer cell

Level (dBm)

Distance

C/I = 13 dB

Level of serving cell

Neighbor cell… not really, it is a cell using identical interfering frequencies.

Depending on C/I, CS2 wont provide the same tput (due to lost packets and retransmissions, the useful tput

decreases down to 10.8)

For instance MCS9 can vary from 45 � 59 kbps

If performing a planning with C/I > 12db : only MS with good C/I will get enough C/I to have max tput.

It is possible to link the C/I and RXLEV to simplify analysis (rxlev = f(C/I), depending on netwpork planning)







1 � 1 � 184

� Packet data throughput (ETSI)

� Maximum (error free transmission) on Air Interface

� at BLER=10% Degradation of RLC by Level and Interference

System Scheme Max RLC data through-

put (RLC payload)

[kbps]

RLC data throughput

at Reference Point

(BLER=10%)

[kbps]

EGPRS MCS-9 59.2 53.3

MCS-8 54.4 49.0

MCS-7 44.8 40.3

MCS-6 29.6 26.7

MCS-5 22.4 20.2

MCS-4 17.6 15.9

MCS-3 14.8 13.3

MCS-2 11.2 10.1

MCS-1 8.8 7.9

GPRS CS-4 20.0 18.0

CS-3 14.4 13.0

CS-2 12.0 10.8

CS-1 8.0 7.2


4.2 Packet data throughput

p.52 and p.64 of 3GPP 45.005

Type of Propagation conditions

channel TU3(no FH) TU3(ideal FH) TU50(no FH) TU50(ideal FH) RA250(no FH)

PDTCH/MCS-5 dB 18 14.5 15.5 14.5 16

PDTCH/MCS-6 dB 20 17 18 17.5 21

PDTCH/MCS-7 dB 23.5 23.5 24 24.5 26.5**

PDTCH/MCS-8 dB 28.5 29 30 30 *

PDTCH/MCS-9 dB 30 32 33 35 *







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4.3 Reference performance point

� ETSI -> Simulation of coding scheme performance under different environment and fading conditions

� typical urban environment with mobile speed of 3 km/h (TU3)

� typical urban environment with mobile speed of 50 km/h (TU50)

� typical hilly terrain with mobile speed of 100 km/h (HT100)

� typical rural area with mobile speed of 250 km/h (RA250)

� The impact of Level and interference has been studied in order to find the minimum required Level and C/I ratio for the reference error performance, defined by a block error rate Block Error Rate (BLER) of 10%, the reference performance point

� Why is this important?

� Saturation effect

For data, most users are static (TU3)

Japanese/Korean behaviour : they use data while in subways and trains. Appearing in France due to tv

online.







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4.4 Saturation effect

Throughput curve as required by ETSI for CS-1and CS-2, typical urban environment with MS speed 3 km/h TU3 with SFH

C/I0

4

8

12

16

20

3dB 7dB 11dB 15dB 19dB 23dB 27dB

kbit/sCS1

CS2The reference performance point is reached at BLER=10%

The following data rates can be achieved at this point:

CS-1: C/I=9 dB =>7.2 kbit/s (saturation: 8 kbit/s)

CS-2: C/I=13 dB =>10.8 kbit/s (saturation: 12 kbit/s)







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4.4 Saturation effect [cont.]

� By increase of the C/I ratio

� Less retransmission has to be performed (less data blocks are erroneous)� since saturation occurs. e.g. for CS-1 starting with 7.2 kbit/s at a C/I ratio of 9dB

� With an increasing C/I ratio the data throughput increases only little up to its maximum value of 8kbit/s (saturation point)

�Data throughput increases

� Due to this saturation effect, a further increase of the C/I ratio does not have large impact on the data throughput of a single coding scheme: possibly a switch to a higher CS may occur (C/I ~ 7 dB for CS-1 to CS-2)

� Reference Performance Point : A tradeoff between the maximisation of the network throughput and excessive C/I constraints.







1 � 1 � 188


4.5 Cell area and throughput

Level of serving cell

1. Throughput at CS-2 saturation point

2. Throughput at CS-2 reference performance point 3. Throughput at CS-1 saturation point

4. Throughput at CS-1 reference performance point

CS-2

CS-1

C/I = 9

dB Level of neighbor-cell

Level (dBm)

Distance

12

810.8

7.2

C/I = 13 dB

RL/MAC net

Data Throughput

(kbit/s)







1 � 1 � 189


4.6 Throughput <-> C/I

� ETSI requirements and Alcatel values for C/Ico and C/Iadj for CS and GPRS

(PDCH) GSM 900 (Requirement for GMSK modulation: C/Iadj = C/Ico – 18dB)

� In general: With higher coding scheme, higher C/I ratios required

� GPRS functionality more ‘sensitive’ against interference

-9-8.2-8.8-6-13-12-13-9C/I adj-

channel

Alcatel

10.811.110.313.16.57.56.711.5C/I co-

channel

Alcatel

-5-4-5-3-9-8-9-5-9 C/I adj-

channel ETSI

13 14 13 15 9 10 9 13 9

C/I co-

channel

ETSI

TU50

ideal FHTU50

TU3

ideal FHTU3

TU50

ideal FHTU50

TU3

ideal FHTU3

CS2CS1

Packet switched

Circuit

switchedGSM 900

Ideal FH : hopping on 4 or more frequencies with at least 800kHz separation between each channel offers

the "ideal FH" diversity gain (4 to 5 dB)







1 � 1 � 190


4.6 Throughput <-> C/I [cont.]

Parameters :

� GPRS

� C/I Throughput

� Co-channelInterferer

� TU 50

� no FH

−5 0 5 10 15 20 25 300

2

4

6

8

10

12

14

16

18

20TU50 (900 MHz) no fh

C / I c o

[dB] →

Thr

ough

put

→

13

−Ju

l−2

00

0 0

9:4

5:4

4

CS−4CS−3CS−2CS−1

CS4 can't resist to interference, even with high C/I, it doesn't reach the saturation point. Expect high

retransmission % when using CS4.

For each C/I, a typical tput can be expected. CS adaptation gives flexibility in case of radio conditions

changes.

At start of a session, which CS to choose?

How would the curve looks like if TU3 was used ? (C/I scale would be squeezed)







1 � 1 � 191

5 (E)GPRS Network introduction







1 � 1 � 192


5.1 GPRS network planning

� Two different cases are possible to introduce GPRS service:

� GPRS Greenfield planning means

� Dedicated analysis of GPRS network design

� All GPRS cells will be designed for maximum throughput performances

� So the (GPRS) cell ranges could be smaller as used to be in a pure GSM network, designed for speech service only

� Introduction of GPRS in operating GSM cells

� GPRS performance is strongly depending on GSM network quality

� Cell ranges are depending from GSM service planning







1 � 1 � 193


5.2 GPRS Greenfield planning

Measures to reach GPRS QoS

RA Planning + CAE Data

GPRS Throughput Analysis

• Traffic Analysis

• Field strength prediction

• Mutual interference calculation

• GSM/GPRS frequency planning

• Cell specific interference calculation

• TRX assignment to GPRS service

GPRS features

GSM features

Objectives

� Traffic Analysis

• PS Traffic

• User Profile

• Market applications

• Customer questionnaire

• Traffic model: Example

• GPRS traffic calculation

- Straight forward

- Erlang C

- Traffic tool

- Exemplary results of the 3 traffic calculation methods







1 � 1 � 194

GPRS traffic calculation

� Traffic Analysis

� PS Traffic

� User Profile

� User Behavior

� Market applications

� Customer questionnaire

� Traffic model: Example

� GPRS traffic calculation

� Straight forward

� Erlang C

� Traffic tool

Different traffic calculation procedure for packet traffic compared to speech traffic calculation







1 � 1 � 195


5.3 GPRS traffic calculation and traffic analysis

� The traffic analysis is done to have the amount of resources (frequencies) one needs to carry GSM+GPRS traffic

� CS traffic demand (Circuit Switched, derived from Erlang B formula)

� PS (Packet Switched) traffic demand has also to be taken into account for the capacity calculation

�What is PS or GPRS traffic?







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5.4 GPRS traffic calculation and PS traffic

� The PS traffic demand (or user throughput demand) is derived from an average traffic data volume generated by each type of GPRS subscriber

� GPRS traffic volume is given on a monthly basis as sum of used applications data volume.

� Today all PS traffic values are based on assumptions until useful experience values are available

� The traffic values are collected in a traffic model

� In general, the traffic from PS services is depending on:

� User profile

� User behavior

� Market applications and service distributions

User profile : what kind of applications ? which volumes ?

User behaviour : what time ? how long ? where ?

Market applications : what is proposed to customers : video on demand ? Live tv ? Mmp games ?







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5.4 GPRS traffic calculation and PS traffic [cont.]

User profile

M arke t app lications

and serv ice d istribu tions

User behav io r Custom er

Questionnaire

T ra ffic ca lcu la tion

T ra ffic m ode l







1 � 1 � 198


5.5 GPRS traffic calculation and user profile

� A user profile defines a typical user for packet data services, using a certain amount of applications

� It is useful to limit the amount of user profiles to keep the calculation simple, e.g. two profiles can be introduced, business and private user







1 � 1 � 199


5.6 GPRS traffic calculation and market applications

� Market applications

� Different services are possible for packet data use e.g. new designed services or services known from the fixed network

� Market applications and user profiles are related to each other, thus some applications are assigned to one user profile only

� Each service is characterized by its occurrence: action time per month and the related bit rate per action.

� In some applications, the data exchange traffic is oriented to downlink, in some others to uplink. Generally the downlink traffic is preponderant in asymmetrical applications such as: web browsing, information downloading, audio downloading etc.

� This shall be taken into account for the dimensioning process: so the dimensioning will be downlink oriented.

Difference between prepaid and postpaid ?

Daily services : weather forecast, news

Hourly : road traffic, market shares

Uplink bias applications : MMS, ftp upload. Create problem for dimesionning ? No, because MMS are

uploaded and then downloaded. They create equal traffic in both ways.

Current Ms use 2ts in uplink, class 11 and 12 are coming (up to 4 TS in uplink, but still simplex.







1 � 1 � 200


5.7 GPRS traffic calculation and user behavior

� Important for the user behavior is the daily distribution

� Duration and occurrence time of busy hour (BH), assumption busy hour is same for CS and PS

� The user distribution over the planning area

� Following definitions can be only expected values for the introduction of GPRS (homogeneous traffic distribution over the cell area is assumed)

� GPRS subscriber percentage (%), related to the total (CS+PD) subscriber number

� GPRS user profiles percentage (%), related to the total GPRS subscriber number

� Geographical percentage distribution (%) of GPRS user profiles related to morphostructure

� Daily GPRS user profile activity (days/month)

Core network : can provide statistics per user (pdp context activation, gprs attach, APN usage, etc…)

Which interface : Gb (mfs-sgsn) , Gn (sgsn-ggsn)

Special tools : astelia







1 � 1 � 201


5.8 Customer questionnaire

� Customer questionnaire

� Data collection from Operator -> Forecast data

� To keep process simple -> 12 Points questionnaire

1. Total amount of GSM subscribers in the network (CS+PS subscribers)

2. Blocking at air interface (speech)

3. Speech traffic per subscriber (mErl/sub)

4. Distribution of CS subscribers to different morpho classes

5. Percentage of GPRS subscribers related to the total amount of GSM subscribers

6. Busy hour occurrence for speech traffic and packet data traffic

This questions are asked to the operator

Speech traffic : from 10mErl to 25 mErl (depends on network age and area covered)

6. Busy hour mix (BHM) : at busy hour, split of different types of traffic







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5.8 Customer questionnaire [cont.]

7. User profile definition

8. Market applications definition and relation to user profiles

9. PS user behaviour/distribution:

� daily GPRS user profile activity (days/month)

� GPRS user profiles percentage (%), related to the total GPRS subscriber number

� geographical percentage distribution (%) of GPRS user profiles related to morphostructure

10. Number of BTS in the existing network

11. Distribution of existing BTS to morphoclasses

12. Number of TRX/BTS, in accordance to morphoclass







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5.9 Traffic Model (Example)

�The table summarizes the assumptions made for the traffic profiles of GPRS subscribers

� (days/month): business 22 days, private 30

� Total GPRS Users 7%: 2% private and 5 % business

� urban = 70% business, 50% private

� rural = 30% business, 50% private

2.3808.124Mbytes/MonthTOTAL

--Mbytes/Month

1024-Kbytes/Min

--Min/MonthAudio (MP3)

e.g. (Access audio files on

the net)

0.1460.586Mbytes/Month

7575Kbytes

28usage/Monthe-Commerce

(e.g. On-line shopping)


6060Kbytes

2025info/MonthInformation (e.g.

Location, event,

transportation services)


100100Kbytes

1025Pages/MonthWWW


30150Kbytes

324mail/MonthE-mail+Attachment

-0.117Mbytes/Month

-20Kbytes

-6Update/MonthRemote access (e.g. WEB

data bases general and

specific (law, medicine,

...)

during GPRS ntroductionMarket Application

PrivateBusinessUser Profile







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5.10 User mapping

� User mapping and Multi-service mapping

� GOAL : to categorize the quality of the three calculation methods

� User mapping

� One certain resource can be shared simultaneously by different users. Behavior in GPRS -> Packet switched service for different users on one timeslot.

User 1

User 2

User 3

User

Timeslot 1

TS 2

TRX

TS 3 TS 4 TS 5 TS 6 TS 7 TS 8

In dimensionning, never take maximum usage as an average value!

User mapping should be quite low, in order to allow a high throughput � but requires higher capacity







1 � 1 � 205


5.11 Multi-Service

� Multi-Service with GPRS

� One user can use different services. So one user is not directly mapped to only one service in the traffic model examination

U se r

Se rv ice 1

e .g . H TTP

Se rv ice 2

e .g . FT P

Se rv ice3

e .g . W AP

Typical http "surfing" usage : 10kB/s (average on 1 hour)







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5.12 QoS per User Application

� QoS per User Application Volume@BH

� Page size

� Queue Delay

� Acceptable delay if no resource is available at service attempt

� Quantile

� Specific elements in the range of a variety X are called quantiles

� Bit rate

Queue delay : how long a user can wait before disconnecting ? Usually for data, user can wait up to 30s.

Quantile : percentage of throughputs measures that are within a certain range (to check) � STANDARD

DEVIATION !!







1 � 1 � 207


5.13 GPRS traffic calculation

� 3 different calculations can be used for GPRS traffic calculation

� Straight forward

� Erlang C

� Traffic tool

+++Traffic Model

_++Erlang C for PS

__+Straight Forward result for PS

Multi-service mapping

QoS per service User mapping







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5.13 GPRS traffic calculation [cont.]

� The straightforward calculation

� gives the smallest number of needed PS TS among the traffic calculation methods

� It calculates for the whole data volume, sum of all users data, the number of PDCH TS needed to transfer this data volume, regardless of data transfer peaks

� This method is not taking into account parallel data transfer, which is the benefit of packet transfer (GPRS).

� So no service attempt queuing and no service multiplexing is taken into account by this method.

� A calculation method to get in the first step of GPRS planning an idea of minimum needed PDCH TS.







1 � 1 � 209



� Erlang C calculation

� gives for a required service attempt probability (Quantile) and the queue delay time of it (e.g. 2 s delay can be set if no resource is available at service attempt), the number of needed resources (TS).

� The result of Erlang C will give the biggest number of needed PDCH TSamong the presented packet traffic calculations.

� The reason is that a constant data flow is considered which is not the case for different applications like WAP

� For all different services the PDCH TS with Erlang C has to be calculated and summarized. Afterwards the sum of PDCH TS for the different services leads to an over dimensioning.

� This method can be used to give very fast a planning result on how many PDCH as maximum can be expected.







1 � 1 � 210



� Traffic Model from Alcatel

� The traffic tool is the most exact method to calculate the needed PDCH compared to the above calculation methods

� Traffic tool is an automated tool (processed by Alcatel-Lucent only)

� Result of this calculation will be most probably between the above calculation methods

� Additionally operator agreed/suggested handling of GPRS channels must be fixed. This is for example the usage of:

� Activation of MPDCH or not

� BCCH combined mode or not

� Usage of Delayed DL TBF Release or not

� QUALITY OF SERVICES [Volume @BH, Page size (KBytes), Queue delay (seconds), Quantile (%), Bit rate (kbit/s)]







1 � 1 � 211



� Traffic Model from Alcatel

� The traffic tool can calculate the result:

� TS needed for CS traffic and signaling in DL/UL

� TS needed PS traffic and signaling in DL/UL

� TRX calculation for CS and PS with application of reuse of CS TS for PDCH (PS) when dynamic/smooth PDCH adaptation and /or fast preemptionfeature is activated







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5.14 Exemplary results of the 3 traffic calculation methods

� General Input data for all 3 calculation methods

� GPRS users (Packet Switched Service)=600 per cell

�WAP users: 60

�WEB users: 180

� MMS users: 360

� Service data size per user in busy hour (per 3600s)

�WAP data size per user 12KB

�WEB data size per user 40KB

� MMS data size per user 40KB

� Coding Scheme : CS-2







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5.14 Exemplary results of the 3 traffic calculation methods [cont.]

� Straight Forward calculation for GPRS Traffic

� Needed transfer rate per service for all users

� WAP 12KB x 8bit/3600s x 60 users = 1.6 kbit/s

� WEB 40KB x 8bit/3600s x 180 users = 16 kbit/s

� MMS 40KB x 8bit/3600s x 360 users = 32 kbit/s

� Total number of needed PDCH's

� Sum of data rate for all services: 49.6 kbit/s

� Expected transfer rate per Timeslot (PDCH)= 10 kbit/s in good radio conditions

Total needed PDCH = 5 PDCH TS / cell

(= 49.6 kbps / 10 kbps)

But assumption is : all users can bare to wait for 3600 sec to finish their download…







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� Erlang C GPRS traffic calculation

� QoS per service

� WAP service: bit rate = 5 kbit/s for 90% Quantile and 2s queue delay

� WEB service: bit rate = 30 kbit/s for 90% Quantile and 2s queue delay

� MMS service: bit rate = 30 kbit/s for 90% Quantile and 2s queue delay

� Number of needed PDCH per service

� The following results calculation can be done with an Erlang C tool. The results are listed for each service

� in this example here for WAP, WEB and MMS







1 � 1 � 215

� Erlang C GPRS traffic calculation

Total number of needed PDCH = 10 PDCH TS� Assumption: Expected rate per TS of 10 kbit/s

� For the WAP service 1 resource of 5 kbit/s is needed = 1 PDCH TS

� For the WEB service 1 resource of 30 kbit/s is needed = 3 PDCH TS

� For the MMS service 2 resources of 30 kbit/s is needed = 6 PDCH TS



E R L A N G C

Volume@BH

Page size (Kbytes)

Subscribers

Queue delay (s)

Quantile

Bit rate

4 0 2 1 8 0 2 s 9 0 . 0 % 3 0

↓1 ← 0 . 5 3 3 3 1 . 8 7 5 0

PDCH =

RO =

MU =

E R L A N G C

Volume@BH

Page size (Kbytes)

Subscribers

Queue delay (s)

Quantile

Bit rate

4 0 2 3 6 0 2 s 9 0 . 0 % 3 0

↓2 ← 1 . 0 6 6 7 1 . 8 7 5 0

PDCH =

RO =

MU =

WAP

WEB

MMS







1 � 1 � 216



� TRAFFIC TOOL version 1.0

� Results of the traffic tool is:

� Used settings in the traffic tool:

� No activation of: Combined mode, DL Delayed TBF Release and MPDCH

� Call Mix Reference used is: Alcatel B7 reference

6 PDCH TS / cell needed

to cope with GPRS traffic

per cell







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5.15 GPRS traffic calculation result

� General GPRS traffic calculation result:

� Needed amount of timeslots for PS traffic

�makes it possible to go to the next step of GPRS network design process

� The user throughput demand is then related to a daily traffic occurrence (user capacity)







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6 (E)GPRS Network design







1 � 1 � 219


6.1 General

� With the input from GPRS traffic calculation the GPRS Design process can start:

� Basis: The knowledge of the amount of timeslots makes it possible to go to the next step of GPRS network design process

� The user throughput demand is then related to a daily traffic occurrence (user capacity) and in combination with the CS traffic demand, the needed equipment amount is calculated:

� Number of timeslots which may be reserved for GPRS in normal and high load state of the BSC

� Number of timeslots which have to be reserved exclusively for GPRS

� Number of remaining timeslots for CS traffic

=> Standard BTS configuration







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6.1 General [cont.]

� Standard BTS configuration

� The result of traffic analysis gives the standard BTS configuration for the different traffic areas. The traffic areas are most commonly linked to a specific morpho class

� Next steps:

1. GPRS Field strength prediction is done as for the GSM network planning [A9155]

2. � Inputs for mutual interference calculation [A9155]

3. � Inputs for a GSM/GPRS frequency planning [A9155/AFP module]







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6.1 General [cont.]

� Cell specific interference calculation

� It is done with the results of the GSM/GPRS frequency planning.

� The cell specific interference calculation will be used to identify less interfered frequencies for TRX assignment.







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6.2 Frequency planning

� Mostly all GPRS networks will be INTERFERENCE limited

� Therefore:

� Proper Frequency Re-use

� Introduction of Frequency hopping [FH doesn't bring better throughput in GPRS and E-GPRS while using high CS & MCS]

� What is the best Carrier for GPRS - BCCH or TCH?

� Make use of improvement strategies

�site design changes

� e.g. antenna changes, electrical down tilt

�site lowering

�site densification

�network expansion/enhancement strategies (like Dual Band)

Interference limited = C/I limited.

Needs an higher C/I to ensure better tput. Redo a frequency planning with greater constraints on C/I

Best carrier = the carrier with the less interference � BCCH ? Normally, yes.







1 � 1 � 223


6.2 Frequency planning [cont.]

� BCCH

� no DTX, PC (Power Control) or FH (Frequency Hopping)

� C/I of minimum 11.5 dB is recommended (Alcatel values)

� Disadvantage: only 6 TS available for GPRS

� TCH

� Hopping, (PC)

� all 8 TS available for GPRS

� Disadvantage: by hopping -> Interference is RF_load dependent

� the increase of RF_load implies a decrease of C/I and therefore of the throughput







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6.3 Throughput

� Throughput -> directly related to link quality and level

� Due to this dependency, the shape of a cell is related to the throughput

� GPRS cells are designed in respect to the

� desired data transmission (throughput)

� behavior of the customers in the planned area

� Attention: GPRS service more sensitive against interference and level than CS service

� Therefore GPRS designed cells are smaller than CS designed ones







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6.4 Link budget

� In general, the link budget calculation is the same like for CS design

� Attention has to be paid to the hardware related values:� BTS/MS performance -> Supplier dependent

� BTS output power & receiver sensitivity according to the coding scheme

� MS output power & receiver sensitivity according to the coding scheme







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6.4 Link budget [cont.]

� Some differences compared to the well-known power budget is the handling of some losses and margins:

� body loss, for PS: 2 dB, due to the fact, that for the most PS applications the MS is not close to the body , but on an other, from the propagation point of view unfavorable position (e.g. on the table)

� interference margin: minimum 3 dB (urban and dense urban area up to 5 dB, depending of the frequency re-use), due to the high dependency of the PS service on C/I

� (lognormal) fading margin can be added to increase the coverage probability from 50% up to 95%; e.g. assuming standard deviation sigma = 7 dB =>fading margin:1.65 sigma ~11 dB







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6.4 Link budget [cont.]

GPRS link budget

example,

dimensioned for

the Evolium BTS

(without TRE):

Evolium/900, 3x4

configuration, 1

X-Pol

Antenna/sector,

in comparison to

a CS link budget

Circuit switched mode CS1 (TU 50) CS2 (TU 50)

TX Uplink Downlink Uplink Downlink Uplink Downlink

Internal Power: 33.00 dBm 45.44 dBm 33.00 dBm 45.44 dBm 33.00 dBm 45.44 dBmIsol.,Comb.,Filter Loss: 0.00 dB 5.01 dB 0.00 dB 5.05dB 0.00 dB 5.05dBOutput Power 33.00 dBm 40.39 dBm 33.00 dBm 40.39 dBm 33.00 dBm 40.39 dBmCable,ConnectorsLoss:

0.00 dB 3.00 dB 0.00 dB 3.00 dB 0.00 dB 3.00 dB

Body Loss: 3.00 dB 0.0 dB 2.00 dB 0.00 dB 2.00 dB 0.00 dBAntenna Gain: 0.00 dBi 18.00 dBi 0.00 dBi 18.00 dBi 0.00 dBi 18.00 dBiEff. Isotr. Rad. Power: 30.00 dBm 55.43 dBm 31.00 dBm 55.43 dBm 31.00 dBm 55.43 dBm

RX Uplink Downlink Uplink Downlink Uplink Downlink

Rec. Sensitivity: -111.00dBm

-102.00dBm

-109.00dBm

-102.00dBm

-105.00dBm

-98.00 dBm

Body Loss: 0.00 dB 3.00 dB 0.00 dB 2.00 dB 0.00 dB 2.00 dB

Cables, ConnectorsLoss:

3.00 dB 0.00 dB 3.00 dB 0.00 dB 3.00 dB 0.00 dB

Antenna Gain: 18.00 dBi 0.00 dBi 18.00 dBi 0.00 dBi 18.00 dBi 0.00 dBi

Diversity Gain: 3.00 dB 0.00 dB 3.00 dB 0.00 dB 3.00 dB 0.00 dBInterference Margin 3.00 dB 3.00 dB 3.00 dB 3.00 dB 3.00 dB 3.00 dBFading Margin 0.0 dB 0.0 dB 0.0 dB 0.0 dB 0.0 dB 0.0 dBIsotr. Rec. Power: -126.00

dBm-96.00dBm

-124.00dBm

-97.00dBm

-120.00 dBm -93.00 dBm

Balance Uplink Downlink Uplink Downlink Uplink Downlink

Max. Path loss 156 dB 151.43 dB 155 dB 152.43 dB 151 dB 148.43 dB

Path loss difference = 3dB standard, 5dB alcatel standard

Uplink Rx sensitivity depends on CS being used.

p. 92 radio network planning aspects







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6.5 Interference analysis on BCCH frequencies

Legend (dB)

> 25 dB

> 16 dB

> 13 dB

> 9 dB

< 9 dB

Network wide C/I (BCCH)







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6.6 Interference analysis on TCH frequencies

Network wide C/I (worst TCH)

Legend (dB)

> 25 dB

> 16 dB

> 13 dB

> 9 dB

< 9 dB

C/I reduction







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6.7 TRX assignment to GPRS service

� Some general considerations apply independently from the BSS software release:

� GPRS/EDGE shall be mapped on the TRX(s) with the best radio quality (lowest interference probability); this can be any TRX in the cell.

� Identification of less interfered frequencies and their ranking

� Assigning the preference for PS traffic handling to the best ranked frequencies (e.g High Power TRX, Full rate capable TRX) with the help of the parameters:

TRX_PREF_MARK; PS_PREF_BCCH_TRX, TRX Classes,

� Since B7 up to 16 TRX per cell are available for GPRS service. So a differentiation of GSM and GPRS TS allocation priority on the TRX must be fixed during planning. The allocation priority for GPRS shall be set according to GPRS QoS needs.

How to map TRE with TRX ?

PS capable TRXs have to be preferentially mapped (from the best choice to the worst) on:

- FR, HP, EGPRS capable TREs

- DR, HP, EGPRS capable TREs

- FR, MP, EGPRS capable TREs

- DR, MP, EGPRS capable TREs

- FR, non-EGPRS capable TREs

- DR, non-EGPRS capable TREs

(When PS_Pref_BCCH_TRX = TRUE, the TRX supporting the BCCH is mapped on the “best” TRE)







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6.8 GPRS Analysis

� GPRS ‘coverage’ analysis

� What area is ‘covered’ with what coding scheme?

� Area and average throughput distribution

� Environment definition (Example)

� TU 50

� GSM 900 Band

� BCCH as GPRS carrier







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6.8 GPRS Analysis [cont.]

�GPRS analysis Steps:

� C/I based analysis

�Coding scheme

�ThroughputAnalysis in respect to:

� Average throughput or/and

� throughout hot spots�







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� GPRS service is C/I limited

� Improvements for a larger CS-4 coverage

-> reduction of the overall interference situation in the network (higher achievable throughput)

Legend (CS value)

CS 4

CS 3

CS 2

CS 1

Network wide Coding Scheme

Distribution (C/I based)







1 � 1 � 234



� The system keeps always the highest coding scheme (and due to this, the highest achievable throughput), until the C/I proportions lead to change to a lower coding scheme

� By driving through the CS4 area from the centerto the border, a stepwise degradationof the throughput depending from theC/I ratio is visible

Legend (kbit/s)

19..20 kbit/s

16..18 kbit/s

14..15 kbit/s

7..13 kbit/s

< 7 kbit/s

Network wide GPRS Throughput

(C/I based)







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6.9 LA and RA planning

� Routing Area (RA) Definition

� CS case with a mobile terminating call:

�the MS in idle mode will be paged in all cells belonging to the LA where the MS is assigned. The signalling effort for paging is thus focused to a certain area, the LA.

� GPRS: the SGSN pages the MS in STANDBY state, in case of a downlink TBF (comparable to a CS MT call).

� Paging GSM+ paging GPRS additional signalling effort will be produced in the network

� ETSI introduced Routing Areas (RA), which are smaller than LA.

�The signalling effort for paging is now more focused to a smaller area. Since not all cells of a LA are involved in the paging process, the signalling load for the cells is reduced







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6.9 LA and RA planning [cont.]

� Routing Area (RA)

� A Routing Area is a sub-set of one LA and identifies one or several cells in a location area.

� The location of a MS in STANDBY state is known in the SGSN on a RA level.

� Each cell in a network is now (additionally to CI and LAC) characterized by:

� Routing Area Code (RA_code) range 0…255

� RA_Colour range 0…7

In SI3, if RA COLOUR = -1 : no gprs in the cell

Allows the mobile to quickly check if change of RA : ra colour change (because SI3 update frequent)







1 � 1 � 237



� Routing Area (RA)

� RA information is sent to MS on BCCH by

� RA_Colour (SI 3 and 4)

� RA_Code (SI 13, less often )

� RA_Colour indicates the MS:

� if GPRS is supported in the cell (if ≠ -1)

� the fast identification of the RA membership of the serving cell and neighbour cells (what cell belongs to what RA)

� As a consequence, the assignment of the cells belonging to RA has to be done carefully, to avoid additional signaling load on the cell (additional to the signaling for the CS traffic too)

Mapping of BCCH data in 3GPP 45.002 (§6.3.1.3)

SI3 : twice in 1.9s

SI4 : twice in 1.9s

SI 13 : once in 1.9s







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� LA planning

� in accordance to the common rules for CS planning, no extra adaptation (e.g. on the neighbour list) has to be made for PS services

� RA planning

� follows in general the rules of the common LA assignment, e.g. avoid roads with fast moving traffic through RA

� The RA planning consists of:

� assignment of each cell to a RA

� assignment of the RA_Code to each RA

� assignment of a RA_Colour to each RA

Routing area code can be, ie, LAC+0,1,2,3...

Routing area color : shouldn't be the same between two areas that are next to each other







1 � 1 � 239



� The following rules are mandatory:

� 256 possible RA_Code (0..255)

� 8 possible RA_Colour_Code (0..7)

� one RA must belong to only one LA, it is not possible to define a RA across a LA border (e.g. 1 cell from LA1 and 2 cells from LA2)

� a RA can contain one or several cells

� one cell can not belong to two RA

� cells from one BTS can be allocated to different RA

� the maximum number of RA in a LA is 256

� it is possible to reuse the RA_Colour in a LA

� two adjacent RA in a LA must have different RA_Colour







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� For the dimensioning of the number of RA in a LA, of the number of cells belonging to a RA and the number of RA_Codes per LA, the following steps are proposed, function of different network growths

� Step 1: Network with low GPRS/E-GPRS traffic

� RA as big as LA =>1 RA_Code (same for each cell) per LA, 1 RA_colour(same for each cell) per LA

� The first introduction step is based on the assumption, that in the beginning not much PS services is expected. The expense of this implementation is low







1 � 1 � 241



� Step 2: Network with medium GPRS/E-GPRS traffic

� The LA is split into maximum 8 RA

� For each RA in a LA one unique RA_Code is assigned

� A balanced number of cells per RA needs to be acquired, however for identified hot spots an unbalanced assignment is possible (smaller RA for hot spots)

� This step represents a reasonable split of the LA into RA if packet data traffic rises

� It can also be carried out right from the start to be prepared for the traffic growth

� The planning effort is medium







1 � 1 � 242



� Step 2: Network with medium GPRS/E-GPRS traffic

� The LA is split into maximum 8 RA

RA 1 RA 2

RA 6RA 5RA 4

RA 3

RA 7 RA 8

RA_C: 0 RA_C: 1 RA_C: 2

RA_C: 3 RA_C: 4 RA_C: 5

RA_C: 6 RA_C: 7







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� Step 3: Network with high packet data traffic or dense network

� LA = up to n RA (max 256)

� If the number of RA in a LA is larger than 9, the RA_Colour reuse is necessary, and a large-scale careful planning is recommended

� As described before, frequent RA change by cell-reselection is not desired =>thus the RA should be not to small

� by reusing the RA_Colour, adjacencies of RA's with the same RA_Colourhave to be avoided







1 � 1 � 244



� Step 3: Network with high packet data traffic or dense network

� LA = up to n RA (max 256)

RA 1 RA 2

RA 6RA 5RA 4

RA 3

RA 7 RA 8

RA_C: 0 RA_C: 1 RA_C: 2

RA_C: 3 RA_C: 4 RA_C: 5

RA_C: 6 RA_C: 7

RA 9

RA 10 RA 11 RA 12

RA_C: 0

RA_C: 1 RA_C: 2 RA_C: 3







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6.10 Quality of Service

� GPRS QoS is not an isolated topic

� It is necessary to use GSM counters in order to complete the analysis of :

� GPRS QoS

� the impact of GPRS on GSM QoS

� Note: for more information refer to the GPRS QoS follow up expert training

GSM QoS

Impact of GSM on GPRS

GPRS QoS







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6.10 Quality of Service [cont.]

� Use GSM indicators in order to complete the analysis of GPRS QoS

� Example :

� high number of TBF establishment failures due to radio problems => check with GSM counters if there are interferences (quality HO, interference HO)

� Use GSM counters in order to complete the analysis of the impact of GPRS traffic on GSM QoS

� Example :

� CCCH load due to GSM and GPRS

� TCH Erlang

� TCH Congestion (call establishment and incoming HO)







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6.10 Quality of Service [cont.]

� OMC-R indicator comparison

� According to GSM, QoS indicators for the Air interface available for GPRS

� Indicators based on counters, computed by the MFS, transferred to the OMC-R

� Note: To obtain the QoS for GPRS, it is not sufficient to study only the GPRS indicators. There is always an influence of GSM service on GPRS service, e.g. TCH congestion in GSM could be influenced by high CS traffic or the additional high packed data traffic.

GSM GPRS

Radio interface indi-

cator

Call setup success

rate

TBF establishment success

rate

Call success rate TBF normal release rate

Call drop rate Abnormal TBF release







1 � 1 � 248

7 Considerable features to reach (E)GPRS target







1 � 1 � 249

7 Considerable features to reach (E)GPRS QoS target

7.1 General

� GSM QoS and Interference problems if existing shall be fixed, e.g. by

� Introduction of Frequency Hopping

� GSM Power Control (UL)

� If the GPRS QoS is still not reached, then

� New GPRS features as mentioned in next slides shall be introduced







1 � 1 � 250


7.1 Optimization campaign on parameters

� If still the GPRS QoS requirement is not fulfilled, then an optimization campaign on parameters has to be started

� Use of unique values of (GPRS) parameter settings has to be checked

� Use of latest Alcatel default parameters

� Optimize parameters for the different GPRS features, if implemented in the network

� TMA (Tower Mounted Amplifier) from hardware point of view can beconsidered to increase UL throughput, see also GPRS power control topic







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7.2 MPDCH

� MPDCH and SPDCH Planning

� The enabling of MPDCH and the decision to allocate them dynamic or static is depending on

� Traffic capacity the operator has for GSM and GPRS

� Traffic capacity the operator can reserve directly to GPRS

� Amount of traffic for GSM (Voice, SMS signaling, Location Area Update signaling) and GPRS (data, signaling, Routing Area Update signaling)

� Subscriber distribution per service and area

� Mobility (cell reselection) of users during GPRS transfer







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7.2 MPDCH [cont.]

� Planning Recommendation on MPDCH

� Till the penetration rate of GPRS MS, which support master channel feature, is unclear the MPDCH should be not enabled

� So it is guaranteed that all GPRS mobiles in the network can access for GPRS service. MS, which do not support MPDCH, cannot access the GPRS service if MPDCH is enabled. Note: MPDCH can be enabled in network mode of operation: NMO I and NMO III.

NO M PDCH

Low prior ity fo r GPRS o r

low GPRS tra ffic?

S ta tic M PDCH

(D ynam ic M PDCH )

YES

G PRS s igna ling

conge stion

Enab le seconda ry M PDCH s depend ing on

G PRS s igna ling need

NO

NO YES







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7.2 MPDCH [cont.]

� Traffic dependent recommendation (with respect to condition for MPDCH):

� Low GPRS traffic

� If GPRS traffic is low no Primary Master Channel needs to be activated

� High GPRS traffic

� Static Primary Master channel� If the available TS are not scarce

� Operator wants the GPRS MS to perform autonomous cell re-selection based on C31 and C32 criterion

� Dynamic Primary Master Channel� If the CS signaling channels CCCH getting overloaded due to high GPRS traffic and signaling in addition to CS signaling







1 � 1 � 254


7.3 Enhanced PDCH Adaptation & Fast pre-emption

� Feature “Smooth/Enhanced PDCH Adaptation” is recommended to be enabled, leads to higher GPRS QoS [B7]

� There are no parameter to control this feature in B9.

� Soft Pre-emption

� T1 reallocation of TBF's whose PACCH is supported by a preempted time slot

� T1 reallocation of TBF's whose MEGCH link becomes too small (basic nibbles are allocated to the CS calls)

� Fast pre-emption� After T_PDCH_Pre-emption = 4s

� Soft pre-empted PDCH's are released

� Other "locked" PDCH's are released

!!! New in B9 !!!

Locked PDCH = PDCH's that are required by the BSC to the MFS for CS calls







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7.4 User multiplexing

� The strategy of the TBF resource sharing is to use the PDCH resources in a most effective way, that means not to ‘waste’ a PDCH just with one user and therefore to limit the available PS capacity. On the other hand, the more users (different TBFs) share a PDCH, the less effective the data flow and the longer the download or upload time is

� Trade-off between radio resource capacity sharing and optimum data throughput

� Since GSM speech service users are still to be preferred, it is recommended to set N_MAX_UL/DL_TBF_PDCH ≠ 1 (e.g.=2)

� E.g. if N_MAX_DL_TBF_PDCH and CS-2 is used, the DL bit rate per MS will be 6.0 kbit/s (=12/2) per used timeslot for this MS

� If operators goal is to maximize the PS throughput then N_MAX_UL/DL_TBF_PDCH = 1 (default value) is recommended







1 � 1 � 256


7.5 PDCH Resource Multiplexing

� Multislot access is the allocation of more than one PDCH to one MS (multislot access). However to prevent one multislot MS to use too many PDCHs each time it wants to transmit data (detriment of other users), following parameter is used:

� MAX_PDCH_PER_TBF : Maximum number of PDCHs, which can be allocated to a single TBF (or MS)

� Range: [1..5], default value: 5 (today’s MS capabilities)

� Radio Network Planning Impacts

� A few multi slot mobiles can occupy all resources with the default value of MAX_PDCH_PER_TBF. Thus the parameter has to be set, depending from the expected load and in combination with N_TBF_PER_S/MPDCH to reflect operator’s strategy on GPRS QoS.







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7.6 Radio (TBF) Resource Reallocation

� With the feature TBF reallocation, the radio resources allocated to a TBF can be changed during TBF lifetime, which increases successful and efficient TS allocation (according to multislot capability) during ongoing data transfer for PS case.


� EN_RES_REALLOCATION is enabling / disabling the Radio Resource reallocation feature per trigger and per BSS

� All event triggers for TBF resource reallocation shall be considered:

� Trigger T1

� Trigger T2

� Trigger T3

� Trigger T4 (new in B8 for EGPRS purposes)

!!! B9 : this feature is always activated !!!Not changeable !

� Trigger T1 (target maintain a TBF alive when its PACCH is fast preempted):

• Reallocate all impacted TBFs using the pre-empted PDCHs instead of releasing them using the

Packet TBF Release procedure

� Trigger T2 (target attempt offering more PDCHs to an MS upon concurrent TBF establishment):

• get rid of the concurrence constraints imposed by the multislot class of the MS and an existing TBF

to offer the best throughput, the initial TBF can be “moved” to other PDCHs

� Trigger T3 (target periodically attempt offering more PDCHs to an MS which has a TBF in the

direction of the bias with less PDCHs than it can support according to its multislot class):

• take benefit of PDCH resource usage variations in a cell to reallocate the resources granted to a

Mobile Station, in case those resources were not using the full multislot class capabilities of the MS

• to offer the best throughput in the direction of the bias and even adapt to bias changes in the

course of a packet transfer

• Parameters for trigger T3 :

- T_CANDIDATE_TBF_REALLOC: Timer value controlling the time duration between successive

resource reallocation attempts for candidate MSs with the trigger T3







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7.6 Radio (TBF) Resource Reallocation [cont.]

� Advantages

� The advantage of the feature TBF resource reallocation is to serve a better PDCH allocation to a TBF (throughput can be optimized), according to the available radio, transmission, DSP and CPU resources, during establishment and lifetime of TBF

� Drawback

� The allocation process is based on the number of PDCHs that the TBF can be mapped on a new resource and not on the throughput the TBF will get on these PDCHs

Consequence: in certain cases, available PDCHs will not be used for TBF reallocation, whilst using them would have improved the TBF throughput







1 � 1 � 259


7.7 Coding Scheme Adaptation

� Different quality threshold are introduced since B7 to optimize coding scheme adaptation algorithm


� Recommendation: Enable Coding scheme adaptation mechanism in GPRS RLC acknowledged, un-acknowledged mode with parameters EN_CS_ADAPTATION_ACK/EN_CS_ADAPTATION_NACK

� Default parameter setting = enable.

� If the network interference is low it allows to start CS-2 usage at the beginning of a TBF:

� TBF_UL/DL_INIT_CS = CS-2 (default setting = CS-2)

� TBF_UL/DL_INIT_MCS = MCS-6 (default setting = MCS-3)







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7.8 Cell Reselection

� Network control order (NC) parameter defines cell reselection mode, GMM state and the presence of PBCCH in the serving cell.

� Independent from the presence of the MPDCH:

� GPRS cell adjacencies are same in packet idle mode as in packet transfer mode

� GPRS cell adjacencies are set equal to the GSM cell adjacencies (i.e. the BA(GPRS) list = BA(BCCH) list )

C1, C2MS autonomous cell

reselection (NC0 mode)

Standby

C1, C2Network controlled


Ready

(or RMM Mode = PTM)

NC2

Not supported in B8NC1

C1, C2C1, C31, C32MS autonomous cell


Ready

C1, C2C1, C31, C32MS autonomous cell


Standby

NC0

Absence of the PBCCHPresence of

the PBCCH

Mode of cell reselectionMS GMM StateNetwork Control Order parameter







1 � 1 � 261


7.8 Cell Reselection [cont.]


� Possible to reselect a cell without GPRS service (if in the target cell GPRS is disabled)

� Recommendation : enable the GPRS service on all cells in order to prevent a MS to reselect a cell without GPRS support

� "NC0" Cell reselection criterion for PBCCH established or not

� MS triggers GPRS reselection according to GSM reselection criteria (C1, C2)


� Generally optimized GSM/CS parameters for cell reselection shall be kept also for PS cell reselection

� Default values for the parameters are kept







1 � 1 � 262


7.8 GPRS Power Control

� Compatibility of GSM and GPRS UL Power control

� For GPRS rollouts it is recommended to disable the GPRS UL PC bysetting: α=0 and ΓTNX=0

� The reasons why GPRS UL PC shall be disabled:

� MS controlled open loop PC is not working reliably (MS software implementation)

� Field tests show a better throughput performance since the acknowledge message is sent in UL with full power

� Remark: It is possible to deactivate GPRS UL power control (GCH=0 and a=0) and to let GSM UL power control activated (EN_MS_PC=enabled, default), different power control parameters for GSM and GPRS

� Increase UL GPRS throughput

� If TMA (Tower Mounted Amplifier) is used and UL GPRS PC is disabled on a site than better throughput in UL is expected







1 � 1 � 263


7.8 Features on DL TBF establishment and release

� 3 different features are presented which preemptively delay the TBF release to speed up the setup of subsequent TBF

� Delayed DL TBF release

� Fast DL TBF re-establishment

� Non DRX Mode

� Their success depends on the users download behavior e.g. how often pages are changed and the content of the downloaded http looks like. For Web browsing and WAP applications where the PS traffic is bursty, the gain of the features to delay TBF release will be very high

� The 3 features are complementary and can be activated independently from each other. Delays to start download of new LLC PDU depending on feature







1 � 1 � 264


7.8.1 Delayed DL TBF release

� This feature should be enabled if there is no lack of resources to achieve higher user application throughput

� Main beneficiaries will be the applications consecutive pings, WAP and HTTP (clustered web page). The round trip time (RTT) can be shortened by the availability of an already opened TBF. This, in turn, is affected by the TBF hold time and the time between pings

� So in fact less signaling is needed for e.g. download of successive WAP pages or HTTP links because there is no need to establish a new TBF during T_DELAYED_DL_TBF_REL time

� T_DELAYED_DL_TBF_REL should be in between of 1.5s up to 2s depending on available resources in the cell. The higher the TS capacity in a cell is the higher the value of T_DELAYED_DL_TBF_REL can be tuned

DL TBF

T3192

Non-DRX mode

DRX_TIMER_MAX

DL TBF establishmentvia PCH or PPCH of MS paging group

DL TBF

T3192

Non-DRX mode

DRX_TIMER_MAX

DL TBF establishmentvia PCH or PPCH of MS paging group

T_NETWORK_RESPONSE_TIME

p.82

During the delayed release of the DL TBF, the BSS periodically sends to the MS a DL RLC data block (with a

polling request) containing a Dummy UI Command which is a LLC PDU whose checksum is deliberately

wrong. This LLC PDU is hence discarded by the LLC layer of the MS.

Sending periodically Dummy UI Commands enables the mobile station to request an UL TBF establishment in

a PACKET DL Ack/Nack message if it has data to send, and prevents defense RLC timers from expiring in the

mobile station.

If new DL LLC PDUs are received for that MS, the DL LLC PDUs can be sent immediately on the DL TBF. If

the BSS does not receive any DL LLC PDU during the inactivity period, it releases the DL TBF through the

normal TBF release procedure.







1 � 1 � 265


7.8.1 Delayed DL TBF release [cont.]

� Delayed Downlink TBF release -> Total TBF release time is:

� T_DELAYED_DL_TBF_REL = T_DELAYED_DL_TBF_REL_RADIO + T_NETWORK_RESPONSE_TIME.

= 800 ms + 700 ms (defaults) = 1500 ms if delayed DL TBF Release is enabled by parameter EN_DELAYED_DL_TBF_REL

� Advantage

� no delay to start DL data transfer for new DL LLC PDUs

� less signaling

� throughput improved for reason: long RTT. RTT can be shortened by the availability of an already opened TBF. This, in turn, is affect by the TBF hold time, and the time between pings.

� Drawback

� waste of resources, TBF is kept open during delayed downlink time, available USF values are limited

T_Delayed_DL_TBF_Rel = T_NETWORK_RESPONSE_TIME (= 1600ms)







1 � 1 � 266


7.8.2 Fast Downlink TBF re-establishment process

� Fast Downlink TBF re-establishment process

� After reception of the final block by the MS and after the sending of the last PACKET DL ACK/NACK message, the MS still listens on the PACCH during T3192 sec

� BSS re-establishes a DL TBF on the PACCH of the previous DL TBF (i.e. to send a PACKET DL ASSIGNMENT message on the PACCH)

� fast DL TBF re-establishment without impacting the (P)CCCH resources; i.e. a new TBF is established but with the parameters of the old TBF (TFI, TAI)

� Rules

� T3192 > MS-BSS roundtrip delay + RRBP maximum duration (120 ms)

� T3192 + T_MAX_EXTENDED_UL + round_trip_delay < 5 sec

� Default Values

� T3192 = 1000ms when non-DRX mode is not activated

� T3192 = 500ms when non-DRX mode is active

Relative Reserved Block Period : waiting time before UL emission (=> for PACCH) is allowed (cf. USF

mechanism)

RRBP : +3RB, +4RB, +5RB or +6RB (approx)







1 � 1 � 267


7.8.3 Non-DRX feature

� Non-DRX feature benefits

� Continuous monitoring of AGCH messages by the MS

� The MFS establishes a DL TBF on the first available AGCH block (without MPDCH) or the first PPCH occurrence (with MPDCH)

� Higher downlink throughput and shorter transfer delay for cell reselection and bursty download application (HTTP, WAP).


� DRX_TIMER_MAX = 2s (Max = 4s) � Non-DRX mode possible for 2 seconds

� If Non-DRX feature possible, influence on following parameters settings:

� BS_AG_BLKS_RES, BS_PA_MFRMS, T_PDA, T_PUA, T_GPRS_assign_AGCH

� T_GPRS_assign_AGCH parameter can be found in the memo MND/TD/SYT/EBR/0342.2001.

� In B7, the default value was set to 0.7 s

The discontinuous (DRX) mode applies when the MS is in packet idle mode. This function allows a MS not to

monitor all PCCCH blocks, but only blocks defined by its paging group. The MS applies existing GSM DRX

procedures if there is no MPDCH.

Remove 0.6 seconds, due to AGCH queuing time. So real time in non-DRX is 1.4s.







1 � 1 � 268

8 GPRS introduction into operational GSM network







1 � 1 � 269

8 introduction into operational GSM network

8.1 General

� Following aspects are considered if GPRS is introduced into a mature GSM network without network design changes

� Different to the approach of GPRS Greenfield planning

� If the operator foresees design changes due to GPRS QoS requirements than traffic analysis and GPRS network design tasks has to be done before the GPRS introduction step

� Actual status of the GSM network

� GSM QoS and Interference

� All GSM network enhancement features and GSM network problems, mainly GSM QoS and interference, shall be fixed before GPRS is implemented

� New network design/frequency planning

� If a new network design and frequency planning is developed to improve GSM QoS and interference, then the implementation of this design should be done before GPRS is implemented







1 � 1 � 270


8.1 General [cont.]

GSM QoS and Interference

problems?

Actual GSM capacity enough to

cope with GSM and GPRS traffic?

New Frequency plan foreseen?

RA planning

CAE data generation

yes

yes

no

no

yes

GSM problem fixing

no

Introduction of GPRS and related features/settings.

Check GPRS throughput map

GPRS

Intr

oduction

How

to reach

GPRS Q

oS?

Task

s befo

re G

PRS

Intr

oduction

Increase capacity

GPRS QoS reached? Considerable features to reach

GPRS QoS target

Optimize GPRS parameters if

needed

Add new GPRS features if needed

GSM QoS and Interference

problems

Implement Frequency Plan

yes

no

no







1 � 1 � 271


8.1 General [cont.]

� Occurred traffic and handled traffic balance

� GPRS QoS requirements

� Operator requirements define the needed GPRS capacity and GPRS QoSper user in relation to specific definitions for user and used service:

� Volume @BH (Kbytes)

� Page size (Kbytes)

� Queue delay (seconds)

� Quantile (%)

� Bit rate (kbit/s)

� Expected GPRS traffic

� The calculation of expected GPRS traffic has to be done before

� Following results will be then available:

� TS needed for CS traffic and signaling in DL/UL and

� TS needed for PS traffic and signaling in DL/UL







1 � 1 � 272


8.1 General [cont.]

� Amount of TS, TRX's & frequencies needed :

� If resources are enough for GSM and GPRS

� TRX assignment to GPRS service and the PDCH planning can be done.

� If resources are not enough for GSM and GPRS

� Additional TRX & frequencies must be allocated to the sites with not enoughtraffic capacity.

� A new frequency planning should be done when a not negligible amount of new frequencies have to be added to a planning area to fulfill (GSM+GPRS) capacity requirements.







1 � 1 � 273


8.1 General [cont.]

� Introduction of GPRS and related features/settings

� The prerequisites for a GPRS analysis are following tasks

� Field strength prediction

� Interference analysis

� If new sites after GPRS analysis are required to fulfill operators GPRS requirements, a new frequency planning with a certain frequency band range planning has to be done.

� Routing area, CAE data

� The routing area (RA) planning is a must for GPRS introduction into GSM network, see chapter 7 for details on RA planning and CAE data generation.







1 � 1 � 274


8.1 General [cont.]

� GPRS QoS increasing tasks to be done are depending on dimensions of QoS requirements. What kind of tasks and references can be done to increase GPRS QoS ? As seen earlier :

� Dedicated TRX for GPRS in a cell can be done if TRX number in the cell is ≥ 2

� Introduction of GPRS Master channels (MPDCH to separate GPRS and GSM signaling

� Open question: Penetration rate of GPRS MS which can decode MPDCH

� The parameters for PDCH dynamic allocation (and TBF resource management) depends on GPRS QoS requirements :

�Weaker GPRS requirements � more TS for GSM can be reserved with a low value of MAX_PDCH

� For GSM tasks see next slides







1 � 1 � 275

9 GSM Network enhancement features & GPRS







1 � 1 � 276

9 GSM network enhancement features & GPRS

9.1 Frequency Hopping

� The dependency between FH usage and Coding scheme distribution and the consequences on CS1-CS3 and CS 4

� Generally Frequency Hopping (FH) leads to Interference averaging. Thus calls having good quality will get worse, bad calls will get better. This is valid for GSM, similar it is valid for GPRS.

� CS1 is used in bad conditions, thus it will be improved if FH isintroduced.

� CS4 is used in very good conditions, which are more seldom in a hopping network. Thus CS4 will perform less good and will be used more seldom.

� The overall gain of CS1 - CS3 will depend on the C/I situation before and after FH.

� CS adaptation parameters can be tuned more optimistic in respect to throughput and Coding Scheme if FH is used:

� CS_QUAL_XX_1_2_FH_Z > CS_QUAL_XX_1_2_NFH_Z







1 � 1 � 277


9.1 Frequency Hopping [cont.]

� GPRS load and GPRS performance

� GSM + GPRS load increases � Higher probability for interference

� Because GPRS performance is mainly based on C/I � it will reduce the performance.


� To reduce the load in the network/cell following GSM activities can be started:

� Adding more resources, frequencies

� Make smaller cell sizes (e.g. achieved by stronger tilt)

� Do proper cell planning







1 � 1 � 278


9.2 µ-cell

� The main advantage of a µ-cell environment may be a better frequency re-use possibility, thus better C/I value and higher throughput can be expected (especially for E-GPRS with higher C/I requirements than GPRS s). Following two steps is proposed for GPRS implementation

� 1. Step: GPRS traffic is low => introduction of GPRS for macro and µ-cell together

� Disadvantages in both layers :

� Emergency capacity on macro cell layer reduced

� Higher blocking probability on µ-cell layer for CS traffic

� Solution:

� Reduction of the maximum GPRS capacity of the µ-cell to 30-50% by parameters setting

� Tuning of the GPRS user access handling (TBF and PDCH share)







1 � 1 � 279


9.2 µ-cell [cont.]

� Step 2: Increasing GPRS traffic => network densification

� Measures:

− Hardware : TRX upgrade, µ-cell and macro cell densification, site design

− Parameter: GPRS capacity and user access handling tuning

� Basis: OMC-R Load measurements and GPRS customer behavior (location)

� Assumption: 80% of packet data traffic is static, 20% is dynamic (driving)

� The strategy is also valid for a different assumption, but this assumption is more probable.

!!! Activate Outgoing Redirection from MICRO !!!EN_OUTGOING_GPRS_REDIR(Umbrella) = DisableEN_OUTGOING_GPRS_REDIR(Micro) = EnableNC_DL_RXLEV_THR(Micro) = -47 dBmNC2_DEACTIVATION_MODE(Umbrella) = at the expiry of the GMM Ready timer







1 � 1 � 280


9.3 Dual Band

� The consequence for the PDCH configuration will be explained related to Alcatel’s dual band approaches.

� Reminder:

� there are no HO in GPRS for PS services

�supported MS classes to be checked

� Two Approaches

� Multiband BSS approach

� Multiband cell approach







1 � 1 � 281


9.3 Dual Band [cont.]

� Multiband BSS approach

� A dedicated BCCH for each cell/frequency band

� Class B and C MS’s can make interband cell reselection during data transmission

� if C2 parameters are used in order to give a higher priority to a given layer for circuit mode

� the same priority is obtained for packet mode

� thus GPRS can not be kept in 900 MHz layer, if GSM MS is sent to 1800 MHz layer

� therefore PS functionality should be configured in both bands







1 � 1 � 282


9.3 Dual Band [cont.]

� Multiband cell approach

� TRX’s of one band are allocated to the outer zone and the TRX’s of the other band to the inner zone.

� The BCCH is configured to the outer zone. The principle is similar to the concentric cell ones.

� During PS traffic, class B and C MS’s will always be served by the outer zone GPRS TRX.

� if C2 parameters are used in order to give a higher priority to a given layer for circuit mode the same priority is obtained for packet mode

� if GSM MS is sent to inner zone in dedicated mode, the GPRS service cannot be ensured in the inner zone

� PS functionality in outer zone only

� No use of C2 to give a higher priority to non-GPRS layer







1 � 1 � 283


9.4 Concentric cell

� For the two possible cases:

� Concentric cells which are disturbing other cells:

�the inner zone is smaller than the outer zone and keeps the disturbing carriers

� concentric cells which are disturbed by other cells:

�the inner zone and outer zone carriers have the same output powers; nevertheless, the size of the inner zone is dimensioned by proper parameter setting

� the same recommendation holds: the TRX for PS traffic must be configured in the outer zone of the concentric cell







1 � 1 � 284

10 E-GPRS







1 � 1 � 285

10 E-GPRS

10.1 E-GPRS main differences

� E-GPRS main differences

� TRX output power

� RX sensitivity

EDGE timeslot GSM900 GSM1800

8PSK TX power 15 W or 41.76 dBm(tolerance –0.5 + 0.5 dB)

12 W or 40.8 dBm(tolerance -0.5 + 0.5 dB)

Reference sensitivity -112 dBm (static MCS-1)• 108 dBm (TU50 ideal FH, MCS1)

• -104 dBm (static MCS-5)- 100 dBm (TU50 ideal FH, MCS5)







1 � 1 � 286

10 E-GPRS

10.1 E-GPRS main differences [cont.]

-110 -105 -100 -95 -90 -85

0

10

20

30

40

50

60MCS-9

MCS-8

MCS-7

MCS-6

MCS-5

MCS-4

MCS-3

MCS-2

MCS-1

Level [dBm]

Thro

ughput [kbps]







1 � 1 � 287

10 E-GPRS

10.1 E-GPRS main differences [cont.]

0

10

20

30

40

50

60

0 5 10 15 20 25 30 35

MCS-9MCS-8MCS-7MCS-6MCS-5MCS-4MCS-3MCS-2MCS-1

Thro

ughput [kbps]

C/Ico(dB)







1 � 1 � 288

11 GPRS traffic calculation example







1 � 1 � 289


11.1 Customer questionnaire (Example) [cont.]

� 1. Total amount of GSM subscribers in the network (CS+PS subscribers)

� 1Mio

� 2. Blocking at air interface (speech)

� 2%

� 3. Speech traffic per subscriber (mErl/sub)

� 20 mErl/Sub rural,

� 25 mErl/Sub urban

� 4. Distribution of CS subscribers to different morpho classes

� 80% urban

� 20% rural)

� 5. Percentage of GPRS subscribers

� 7% of total GSM subscribers

� 6. Busy hour occurrence for speech traffic and packet data traffic:

� Speech traffic busy hour: 8-11, 13-17 and 18-22 o’clock

� Packet data service hours: Business: 8-11 and 14-17, private 14-20 o’clock

� 7. and 8. see table







1 � 1 � 290


11.1 Customer questionnaire (Example) [cont.]

� 9. PS user behaviour/distribution:

� daily GPRS user profile activity (days/month):

�business 22 days,

�private 30 days

� GPRS user profiles percentage (%), related to the total GPRS

� subscriber number = 7%: 2% private and 5 % business

� Geographical percentage distribution (%) of GPRS user profiles related to morphostructure:

�urban = 70% business, 50% private

�rural = 30% business, 50% private

� 10. Number of BTS in the existing network

� 2000 BTSs

� 11. Distribution of existing BTS to morphoclasses:

� 1200 BTSs in urban,

� 800 in rural

� 12. Number of TRX/BTS, in accordance to morphoclass:

� 3*2 configuration in urban, 3*1 configuration in rural







1 � 1 � 291


11.2 User and area distribution determination

� According the questionnaire, the GPRS user distribution will be calculated

� Due to the different network capacity in urban and rural area and the different ratio of business and private users in the area, the GPRS and speech subscriber are split to urban and rural area

Total GSM subscriber: 1 MioBusiness Private

GPRS share 7% total 5% (50000 subs.) 2% (20000 subs.)Urban area 70% (35000) 50% (10000)Rural area 30% (15000) 50% (10000)

Total CS subscriber: 1 Mio Urban area 80% (800000 subs.) Rural area 20% (200000 subs)

Packet data

Speech







1 � 1 � 292


11.3 Traffic demand for CS traffic

� The traffic demand for CS subscribers

� 2% blocking during the busy hour

� Urban area 25 mErlang/Subs.

� Rural area 20 mErlang/Subs.

� Assumption: Homogeneous traffic distribution in each morpho class

Total CS subscriber: 1 Mio

Urban area Rural area

Traffic [Erlang] 20000 4000







1 � 1 � 293


11.4 Traffic demand for packet traffic

� The traffic demand for PS is calculated in two steps:

� First step: throughput demand per user profile calculation (due to the different user behaviours)

� Second step: Relation of throughput demand to the total subscriber amount in urban and rural area

� Assumptions:

� packet data traffic per month is user profile depending (e.g. not during the whole month, like speech traffic)

� PS traffic is not to be spread over the whole day, there are now service hours/day, depending on the user profile

� Packet data traffic occurs only during the service hours.

� Packet data traffic is homogeneously distributed over the service hours,

� During service hours, the user is continuously active (worst case calculation)







1 � 1 � 294


11.4 Traffic demand for packet traffic [cont.]

� What is the busy hour?

� 1. CS traffic is maximum

� 2. PS traffic is also maximum in that period

� Exception:

�CS and PS busy hour not overlapping -> separate dimensioning

Reserve still sufficient capacity for CS during PS busy hour!

�PS user profile service hours not overlapping

Use user profile with highest throughput demand







1 � 1 � 295



� In our example, the service hours for PS traffic are in total 6 hours, but from 14 to17 o’clock business and private subscriber will make data traffic at the same time

� Thus the busy hours for data traffic are these 3 hours

� It is also visible, that during that time, also for speech traffic a busy time occurs

� Busy hour: GPRS traffic dimensioning will be 14 to17

� Speech

� Packet

� Business

� Private

8 11 1314 17 20 22







1 � 1 � 296



� Packet data throughput demand (user profile):

� Packet data throughput demand (total network):

Business Private

Traffic/month [Mbyte] 8.124 2.380

Traffic/month [kbit] 68149.05=

8.124*1024*1024*8/1000

=19964.88

traffic volume demand /day

[kbit]

3097.68

=68149.05/22 days

665.49

for 30 days

throughput demand /service

hours [kbit/s]

0.14

=3097.68/(6 hrs*3600)

0.03

6 serv. hours

throughput demand /busy hours

[kbit/s]

0.14

during 3 busy hours

0.03

during 3 busy hrs


Business Private Business Private

throughput demand

/busy hours [kbit/s]

4900 300 2100 300

Total: 5200 2400







1 � 1 � 297


11.5 Network capacity calculation

� For CS traffic:

� The actual network capacity is sufficient to handle the CS traffic during the busy hour by assuming a maximal blocking probability of 2%

Total BTS 2000


BTS 1200 800

Configuration 3x2 3x1

Capacity/Erlang 2%

Blocking

29520

=1200*3*8.2

6960

=800*3*2.9

CS traffic demand 20000 4000







1 � 1 � 298


11.5 Network capacity calculation [cont.]

� Network throughput capacity for PS traffic:

� The network throughput capacity for PS traffic is based on the cell throughput capacity

� For this dimensioning example it is appropriate to consider the result of the cell ranges dimensioning example

� According to it, 59% of the cell area is operated in CS-2 and 41% in CS-1 mode

� The cell throughput capacity can be estimated with a data rate of (0.41*8+0.59*12) kbit/s = 10.36 kbit/s per timeslot







1 � 1 � 299



� The network capacity is depending from the allocated TS for PDCHuse:

� parameter MAX_PDCH in cell's CS normal load situation

� parameter MAX_PDCH_HIGH_LOAD in cell's CS high load

� parameter MIN_PDCH (optional)

� Example:

� MAX_PDCH is set to 8 TS for the 3x2 BTS configuration (2nd TRX allocated for GPRS),

� MAX_PDCH for the 3x1 BTS, only 7 TS can be allocated for packet data (TS 0 is reserved for BCCH)

� MAX_PDCH_HIGH_LOAD =1 (Under CS high load conditions, only one TS will be present for packet data usage)







1 � 1 � 300



Total BTS 2000


BTS 1200 800


Total Available TS, BCCH not incl. 54000

=(7+8)*3*1200

16800

=7*3*300

Available TS, BCCH not incl.

MAX_PDCH_GROUP = 8 TS

28800

=8*3*1200

16800

=7*3*800

Available TS if BSC in HIGH_LOAD

MAX_PDCH_HIGH_LOAD = 1 TS

3600

=28800/8

2400

=16800/7

Capacity [kbit/s]

(10.36 kbit/s /TS)

298368

=28800*10.36

174048

Capacity [kbit/s]

if BSC in HIGH_LOAD (10.36 kbit/s /TS)

37296

=3600*10.36

24864







1 � 1 � 301


11.6 Traffic dimensioning

� Allocating TS to GPRS traffic reduces the capacity within the circuit switched design

� For the busy hour, the BSC is in high load situation, i.e the maximum of PDCHs is equal to MAX_PDCH_HIGH_LOAD (resource control)

� The following table gives the CS capacities based on a blockingprobability of 2% (in Erlang), according to the amount of allocated timeslots for GPRS in BSC high load situation

Amount PDCHA-mountof TRX

A-mountSDCCH

AmountTCH

+PDCH

0 1 2 3 4 5 6 7

1 TRX 1 7 2.93 2.27 1.65 1.09 0.6 0.2 0.02 02 TRX 2 14 8.2 7.4 6.61 5.84 5.08 4.34 3.62 2.933 TRX 3 21 14.03 13.18 12.33 11.49 10.65 9.82 9.01 8.24 TRX 4 28 20.15 19.26 18.38 17.50 16.63 15.76 14.89 14.035 TRX 4 36 27.34 26.43 25.52 24.62 23.72 22.82 21.93 21.036 TRX 5 43 33.75 32.83 31.91 30.99 30.08 29.16 28.25 27.34







1 � 1 � 302


11.6 Traffic dimensioning [cont.]

� MAX_PDCH_Group = 8 or 7

� MAX_PDCH_HIGH_LOAD = 1

� Network capacity for CS and PS traffic (1 TS for PS):

Total BTS =2000


number of BTS 1200 800


Capacity/Erlang @2 % Blocking 29520 6960

Capacity/Erlang @2% Blocking and 1 PDCH 26640

=1200*3*7.4

5448

=800*3*2.27

Speech

CS traffic demand [Erl] 20000 4000

Capacity [kbit/s] (10.36 kbit/s /TS) 298368 174048

Capacity [kbit/s] if BSC in HIGH_LOAD

(10.36 kbit/s /TS)

37296 24864

Packet

data

PD busy hour throughput demand [kbit/s] 5200 2400







1 � 1 � 303



� Conclusions:

� Network is able to serve CS traffic.

� One TS is necessary to handle PS traffic.

� One TS is sufficient for PS traffic during the busy hour.

� No CS service degradation during busy hour.

� The reservation of 1 TS for PS traffic represents no service degradation for CS traffic, since the remaining network capacity is still sufficient to handle the CS traffic.

� To guarantee a permanent PS service independent form the load situation, the parameter Min_PDCH_GROUP was set to 1 (I.e. 1 TS/ cell is permanently reserved for PS service and not available for CS traffic),however Min_PDCH_GROUP = 0 is recommended (load reduction on Atermuxinterface)







1 � 1 � 304



� Further iterations would be necessary (increase of MAX_PDCH_HIGH_LOAD) if the PS traffic demand could not be handled with MAX_PDCH_HIGH_LOAD = 1 timeslot

� Further, if the CS traffic demand could not be handled with the remaining timeslots some measures are necessary e.g.:

� add a TRX to the considered serving cell

� shrink the cell size of the serving cell (e.g. introduce downtilt) and increase the cell size of a neighbouring cell which offers sufficient capacity to handle the traffic demand surplus of the serving cell

� reduce interference (network changes) to get higher average throughput







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� In the Alcatel GPRS implementation step 1, the number of TRX'swhich can be allocated to GPRS is maximum NTRXGPRS =1.

� In our worst case consideration, this TRX comes to its limit when the packet throughput demand is higher than the throughput capacity and cannot be satisfied even if the number of allocated TS for PS reaches Max_PDCH_Group







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Abbreviations and Acronyms

Switch to notes view!ALMAP: ALcatel MAnagement Platform APN: Access Point Name AS: Alpha Server (Compaq) BG: Border Gateway BSC: Base Station Controller BSS: Base Station Subsystem BSCGP: BSC-GPRS Protocol BSSGP: BSS-GPRS Protocol BVCI: BSSGP Virtual Connection Identifier CCBS: Customer Care and Billing Center CCU: Channel Codec Unit CDR: Call Detail Record CG: Charging Gateway CS: Circuit Switching DHCP: Dynamic Host Configuration Protocol DL: Down Link DLCI= Data Link Connection Identifier DNS: Domain Name System EDGE: Enhanced Data rates for GSM Evolution FUMO : Frame Unit Module FR: Frame Relay GPRS: General Packet Radio Service GGSN: Gateway GSN GMM: GPRS Mobility Management GR: GPRS Register GSL: GPRS Signaling Link GSM: Global System for Mobile communication GSN: GPRS Support Node GSS: GPRS Sub-System GTP: GPRS Tunneling Protocol HLR: Home Location Register HSCSD: High Speed Circuit-Switching Data IMSI: International Mobile Subscriber Identity IP: Internet Protocol ISDN : Integrated Service Digital Network ISP: Internet Service Provider LAN: Local Area Network LLC: Logical Link Control MAC: Medium Access Control MFS: Multi-Bsc Fast packet Server MNRG: Mobile Not Reachable for Gprs MS: Mobile Station MSC: Mobile Switching Center MT: Mobile Terminal NE: Network Element NMC: Network Management Center NNM: Network Node Manager NRPA : Network Requested PDP Context Activation NSAPI: Network Service Access Point Identifier NSC: Network Service Control layer NSEI: Network Service Entity Identifier NSS: Network Sub-System NS-VC: Network Service- Virtual Circuit NTP: Network Time Protocol DB : On Demand Bandwidth OMC: Operation & Maintenance Center OS: Operation System PAGCH: Packet- Access Grant Channel PCCCH: Packet- Common Control Channel

PCO: Protocol PCU: Packet Control Unit PDCH: Packet Data CHannel PDN: Packet Data Network PDP: Packet Data Protocol (IP or X25) PDU: Protocol Data Unit PPCH: Packet- Paging CHannel PRACH: Packet- Random Access CHannel PS: Packet Switching P-TMSI: Packet- Temporary Mobile Subscriber Identity PVC: Permanent Virtual Circuit P-VLR: Packet- Visitors Location Register QoS: Quality of Service RA: Routing Area RIP : Routing Information Protocol RLC: Radio Link Control RADIUS: Remote Authentication Dial In Use Service RRDTUF : Roaming Restriction Data Towards Unknown Foreign PLMN RRM: Radio Resource Management RSZ : Regional Subscription Zone SGSN: Serving GSN SM: Session Management | Short Message SMS: Short Message Service SMS-C: SMS-Center SNDCP: Sub Network-Dependent Convergence Protocol SNMP: Simple Network Management Protocol SNS: Sub-Network Service layer TBF: Temporary Block Flow TC: Trans Coder TCH: Traffic CHannel TCP: Transmission Control Protocol TDMA: Time-Division Multiplexing Access TFI: Temporary block Flow Identifier TID: Tunnel IDentity TLLI: Temporary Logical Link Identity TMN: Telecommunication Management Protocol TS: Time Slot UDP: User Datagram protocol UL: Up Link UMTS: Universal Mobile Transmission System WAP: Wireless Application Protocol WAN: Wide Area Network







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End of ModuleEVOLIUM BSS – GPRS and EGPRS

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58537348 GPRS EGPRS Planning Xavier

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