GPRS EGPRS Network Planning B10.pdf

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Section 1 Module 1 Page 1

All Rights Reserved 2007, Alcatel-Lucent

3FL 38020 ACAA Edition 2

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EVOLIUM BSS - GPRS and EGPRS Radio Network Planning


GPRS and EGPRSRadio Network Planning


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Radio Network Planning - GPRS and EGPRS

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

Radio Network Planning

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1 1 4

Objectives


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1 1 5

Table of Contents

Switch to notes view!Page

1 Basics 91.1 Service Overview GPRS 10

1.2 Service Overview EGPRS 111.3 Support of GPRS QoS classes 12

1.3.1 Radio Network Planning Impact 131.4 Dual Transfer Mode 14

1.4.1 Radio Network Planning Impact 151.5 (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 31

1.14 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 58

1.27 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 80

1.40 TRX Classes Concept 811.41 Two Abis Links per BTS 84

2 B9 features 852.1 Enhanced Packet Cell Reselection (R4 MSs) 86

2.1.1 Radio Network Impact 872.2 Extended Uplink TBF Mode 882.2 Radio Network Planning Impact 892.3 Enhanced support of E-GPRS (EDGE) in uplink 91

2.3.1 Radio Network Planning Impact 932.4 Counter Improvements for Release B9 94

2.4.1 Radio Network Planning Impact 982.5 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 102

2.6.1 Radio Network Planning Impact 1052.7 M-EGCH Statistical Multiplexing 106

2.7.1 Radio Network Planning Impact 1082.8 Dynamic Abis allocation 109

2.8.1 Radio Network Planning Impact 1102.9 Enhanced transmission resource management 1112.10 RMS_I1 Improvements 112

2.10.1 Radio Network Planning Impact 1132.11 RMS_I2 Improvements 114

2.11.1 Radio Network Planning Impact 1153 (E)GPRS Radio Algorithms 116

3.1 Cell Reselection Overview 1173.2 Cell reselection: NC0 mode, no PBCCH established 1213.3 Cell reselection: NC0 mode, PBCCH established 123

3.4 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 166

3.17 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 207

5.14 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 263

7.8.1 Delayed DL TBF release 2647.8.2 Fast Downlink TBF re-establishment process 266

7.8.3 Non-DRX feature 2678 GPRS introduction into oerational GSM network 2688.1 General 269

9 GSM Network enhancement features & GPRS 2759.1 Frequency Hopping 2769.2 -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 292

11.4 Traffic demand for packet traffic 29311.5 Network capacity calculation 29711.6 Traffic dimensioning 301


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All Rights Reserved Alcatel-Lucent 2007EVOLIUM BSS - GPRS and EGPRSRadio Network Planning

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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 theconnection 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 adjacentchannel as GMSK makes possible to integrate EDGE channels intoexisting 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-timeconversation. Speech and video conferencing tools are someexamples of such applications

The streaming class corresponds to a real-time stream and enforcesmainly 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 Internetapplications 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 Effortservices. Applications that make use of this class might be e-maildownloading, 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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1.3.1 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 thecell by allocating, in a selective manner, resources for (CS and) PScalls. Here a traffic capacity gain is expected (higher traffic levelscan 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 isbroadcasted 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 themobile station in the RLC extended header during contention resolution. The PFI is not used for contentionresolution 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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1.4 Dual Transfer Mode

This feature allows a dual transfer mode capable MS to use a radioresource 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 tothe throughput expected in PS services. Only multislot operationDTM MSs are supported.

In Alcatels implementation, the Gs interface is required to supportDTM to ensure CS paging co-ordination. It avoids the BSS to ensurethe paging co-ordination.

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

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

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


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1.4.1 Radio Network Planning Impact

Some restrictions towards BSS in deploying DTM exist. They arepresented below: Half rate

Support of half rate configurations (one single timeslot encompassing one halfrate circuit channel + one half rate packet channel) was not considered in thefirst 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 MSis 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 themacro cells. It means that the BSS shall allow a PDCH used by a MS operating inDTM 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

Class 1 2 3 4 5 6 7 8 9 10 1 1 12 1 3 1 4 15 1 6 1 7 1 8 19 2 0 21 2 2 2 3 24 2 5 2 6 27 2 8 2 9

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

Timeslots 2 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 classE.g. the multislot class of the mobile can be 3 RXs + 2 TXs (class 6) in pure GPRSmode 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 transmittedTSs 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 TSshall 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 beable to open a measurement window.

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


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1.6 (E)GPRS General Architecture

(E)GPRS defines a network architecture dedicated to packet servicedomain, 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 linksthe BSS to PDNs (packet data networks). The BSS is used for bothcircuit-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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1.6 (E)GPRS General Architecture [cont.]

(E)GPRS general architecture

Gb

Interface

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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1.7 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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1.7 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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1.7 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 theMSC, which is linked to several BSSs. It keeps track of the individual MSslocation and performs security functions and access control

Gateway GPRS Support Node (GGSN), which is linked to one or severaldata networks, provides interworking with external packet-switchednetworks and is connected with SGSNs via an IP-based GPRS backbonenetwork


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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 1bisGSM 08.14

Um Abis / AterMS MFSBTS Gb SGSN

L1-GCHLayer 1 GPRS

Channel

L2-GCHLayer 2 GPRS

Channel

BSSGPBSS 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

BSSGPBSS 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:

Applicatio

nexample

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 bythe 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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1.9 Alcatel (E)GPRS BSS Hardware support

BTS: Support of EGPRS (EDGE) in all BTS A9100 EVOLIUM Evolutionequipped 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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1.10 Modulation Technique: 8-PSK only for EGPRS

Q

I

010

011

100

101

111

110

001

000

Q

I

111

110

001

000 100

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

000 100

101

010

011

Q

I

111

110

001

000 100

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

I

dB

(147 bits)

PN

0

-20

8-PSK = Phase Shift Keying

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

An 8PSK signal carries three bits per modulated symbol over the radiopath 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 theamplitude of the carrier which varies over time.

An 8-PSK signal carries three bits per modulated symbol over the radio path, which allows totriple 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 3/5.2seconds (577 s). (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 encryptedbits + 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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1.11 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 averagepower is lower than the peak power

8-PSK power < GMSK power

the difference is called average power decrease (APD) or powerback 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.


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1.11 8-PSK TRA Power Aspects [cont.]

Unbalanced BTS configuration

Case 1: BS_TXPWR_MAX=0

Case 2: BS_TXPWR_MAX0

APD, takes into account theBS_TXPWR_MAX and consequently theEffective 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) considersonly the GMSK sector power without the

BS_TXPWR_MAX

8-PSK 3 dB indicates that is a highpower TRE

GMSK POWER

8-PSK POWER

ATTENUATIONBS_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

= APDAPD = 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.


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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 andduplexer 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)


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3rd step: 8-PSK Delta computation

TRE 1 = 42.1 39.6 = 2.5 dBm < 3 dBm 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 dBm

APD TRE 2..4 = 40.1 37.4 = 2.7 dBm

3GPP 05.08 constraint on the transmitted power of BCCH frequency:BCCH frequency shall usually be transmitted at a constant level. A tolerance has beenintroduced 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 allocatepacket 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 shouldbe 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


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1.12 (E)GPRS Radio Blocks Structure

In order to be transmitted over the air interface, the LLC data issegmented 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 blockthere is no multiplexing of different users possible

the whole information belonging to one radio block is transmitted uponchannel 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)


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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


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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 codingprocedure

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


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1.13 GPRS Channel Coding [cont.]

Four different coding schemes, CS-1 to CS-4, are defined for theGPRS 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 Block

Check 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 rateconvolutional coding for error correction that is punctured to givethe 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 forGPRS signaling (even for EGPRS)


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1.13 GPRS Channel Coding [cont.]

8.00.50Half rate convolutionalcoding

GMSKCS-1

12.00.66Half rate convolutionalcoding, punctured

GMSKCS-2

14.40.75Half rate convolutionalcoding, punctured

GMSKCS-3

20.01.00No codingGMSKCS-4

Maximum data rateper TS (RLC payload)

[kbps]

Coderate

Coding schemesfor RLC data block

Modulationschemes

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 4consecutive TDMAs (4 PDCH)

GPRS RADIO BLOCK

Release B8


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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 CheckSequence (BCS) to each RLC data block, for error detection

Second step consists of adding six tail bits (TB) and a 1/3 rateconvolutional coding for error correction that is punctured to givethe 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 thedata 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.


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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, areadded to the data bytes

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

impact on retransmission

Offset the GPRS disadvantage on retransmission


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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 Apadding

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).


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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 payloadthroughput= 592 bits / 10 ms = 59.2Kbps

USF HCSRLC/MACheader

E FBIRLC Data Block

= 592 bitsBCS TB E FBI

RLC Data Block =592 bits

BCS 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:


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8.80.531/3 rate convolutionalcoding, punctured

GMSKMCS-1


GMSKMCS-2

14.80.801/3 rate convolutionalcoding, puncturedGMSKMCS-3


GMSKMCS-4


8PSKMCS-5


8PSKMCS-6


8PSKMCS-7


8PSKMCS-8


8PSKMCS-9

Maximum data rate per TS (RLCpayload)

[kbps]

Coderate

Coding schemes

for RLC data block

Modulationschemes

Scheme

Uplinktransfer


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1.15 Radio Link Adaptation Overview

(M)CS schemes are dynamically selected based on the quality of theradio 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 measurementsreported by the MS for the downlink path and by the BTS for theuplink path


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1.16 Automatic ReQuest for repetition (ARQ)

In the ARQmethod, when the receiver detects the presence oferrors 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 ARQmechanism. This applies for both GPRS and EGPRS mode

Type-II hybrid ARQmechanism, 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 (3GPPrequirement)

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


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1.17 Type-I ARQ mechanism

In the selective type-I ARQmechanism, the receiver discards theerroneous 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 RLCblocks

MS

Uplink RLC data block B1 / PDTCH (1)

MFS

Packet Uplin kAck/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 datablock is only based on the current transmission.

The type 1 ARQ mechanism is always used for the GPRS


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1.18 Type-I ARQ in GPRS

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

Before its transmission over the radio interface, the LLC frame is segmentedinto payload units according to CS that will be used to transmit the radioblock

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

If the radio conditions have changed and the coding rate is not appropriate tothem, the receiver will never be able to decode the retransmission of the RLCdata block. This will lead to the release of the TBF and the establishment of anew one in order to transmit the LLC frame

In order to avoid this problem, the choice of the CS on the network side has tobe made carefully. This often results in an non-optimized use of the radiointerface, leading to a reduction of network capacity compared with itstheoretical capacity

GPRSDRAWBACK


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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 datablock, 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 isdecreased 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 ofan 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 thelast-ordered MCS


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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 radiodisturbances

In the IRmechanism:

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 previouslyreceived 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 onlyavailable 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 datablocks 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 ofthe RLC block.

Remark : according to the 04.60 (RLC/MAC layers) GSM recommendation, the soft-combining inside the MSreceiver 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 payloadunits).

If the "MS OUT OF MEMORY" field is set by the mobile in the EGPRS Packet DL Ack/Nack message, the type I ARQshall 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 notcorrectly decoded).


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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 blockusing the puncturing scheme P1 and

MCS-6. B1 is not successfullydecoded by the MS. The MS storesthe received block

(2) The MS requests a selectiveretransmission of the erroneousblock, in the next EGPRS Packet DLAck/Nack

(3) The MS retransmits the DL datablock using a new puncturingscheme P2 and the same MCS-6.If the block header is correctlydecoded, the MS decodes the data

making soft combination with theprevious 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 PS1MCS9 MCS6

PS2 PS2

PS1 PS3MCS6 MCS9

PS2 PS2

MCS7 MCS5 PS1, PS2 or PS3 PS1

MCS5 MCS7 PS1 or PS2 PS2

All other combinations Any PS1


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B9 release: the IR mechanism is implemented in uplink anddownlink

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

IR feature is always running in the EGPRS MS receivers, except whena memory shortage is reported by the MS the stored packets arediscarded and type-I ARQ is set !

Parameter for IR activation:

EN_FULL_IR_DL which enable or disable the RLC data segmentation forretransmissions

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 isperformed with MCS-6 (no segmentation, ARQ Type-II)


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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 packetdata traffic (GPRS/EDGE), over the radio interface

PDCH group

The available PDCHs 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 maximumnumber of TRX / cell)

16 TRX/cell achieved with help of the B7 feature cell split over 2 BTSs, EVOLIUM BTS


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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 areused 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


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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 broadcastingsystem information (SI)

PCCCH (Packet Common Control Channel) used to initiate packettransfer

PRACH (Packet Random Access Channel)

PPCH (Packet Paging Channel)

PAGCH (Packet Access Grant Channel)!!! MASTER CHANNEL ONLY !!!


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1.22 (E)GPRS Logical Channels [cont.]

PTCH (Packet Traffic Channel) used for user data transmission andits associated signaling

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

PACCH (Packet Associated Control Channel)

Bidirectional channel, dynamically allocated on block basis, used to carrycontrol data

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

PTCCH (Packet Timing Advance Control Channel) used forcontinuous timing advance mechanism

Bidirectional channel allocated on the same PDCH as the PACCH


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1.23 Master/Slave PDCH concept

A PDCH which carries a PCCCH or/and a PBCCH channel is calledMaster 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)


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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 anumber of RLC/MAC blocks carrying one or more LLC PDUs

TBF is only temporary and maintained for the duration of the datatransfer

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


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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. DLand 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


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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 PDCHs

A maximum number of UL/DL_TBF can share the same PDCH in UL and DLdirection 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 forradio resource reallocation


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1 Basics

1.25 Resources Sharing [cont.]

Multislot usage

Refers to the case when 1 user can request at once more than 2 PDCHresources for the data transmission

Up to 5 PDCH on different (but consecutive) timeslots on the samefrequency could be allocated to one mobile at the same time (MSmultislot 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 PDCHonly if there is no user multiplexing


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1 Basics


PDCH Multiplexing example:

lets assume that the data for user 1 has a length of 3 blocks (length ofTBF 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 inconsecutive order:

as soon as one block of user 1 is transmitted, another block of user 2 can betransmitted, 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


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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


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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 onthe RLC block header

UL TBF (PDTCH and PACCH)

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

If the MS receives its USF on the DL block n of PDCH 5, it can transmit inUL 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 RLCblock 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 allocatedPDCH.

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


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Example of a Uplink Block Flow scheduling:

1 Basics

1.26 MS multiplexing co-ordination [cont.]

DownlinkDownlinkDownlinkDownlink Uplink UplinkUplinkUplink

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 No

Emission

PRACH

Bn+5 TFIb USFj PACCHa

Bn+6 TFIa USFk PDTCHj


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1.27 GPRS mobility management (GMM) states for MS

Idle

Ready

Standby

GPRSattach

GPRSdetach

PDU transmissionTimerexpiry

Timerexpiry

Idle

the MS is not attached to thepacket network: paging is notpossible

Ready

the MS location is known withthe 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 morephysical 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 Idlemode 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.

Standbyis 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.


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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 ofLLC 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 readytimer is no more running

GMM Standby

PIM: TBF closed but GMM ready timer is still running

PTM: TBF opened

GMM Ready

RR Operating ModesGMM States


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1 Basics

1.29 Attach procedure

Aim

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


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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


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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 datanetwork can begin


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1 Basics

1.31 Location management

MS enters in a new cell

New cell inside th

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GPRS EGPRS Network Planning B10.pdf

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