Tmo54048_gprs & Egprs Planning_b10

7/30/2019 Tmo54048_gprs & Egprs Planning_b10

1/328

All Rights Reserved 2010, Alcatel-Lucent

TMO54048 Edition 2

Section 1 Module 1 Page 1

Do not delete this graphic elements in here:


E-GPRS RNP (Radio Network Planning) B10 Fundamentals

TMO54048

E-GPRS RNP (Radio NetworkPlanning) B10 Fundamentals


2/328


TMO54048 Edition 2


Radio Network Planning - GPRS and E-GPRS

All Rights Reserved Alcatel-Lucent 2007E-GPRS RNP (Radio Network Planning) B10Fundamentals

1 1 2

Blank Page

This page is left blank intentionally


3/328


TMO54048 Edition 2




1 1 3

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


4/328


TMO54048 Edition 2




1 1 4

Objectives


5/328


TMO54048 Edition 2




1 1 5

Table of Contents

Switch to notes view! Page

1 Basics 91.1 Service Overview GPRS 101.2 Service Overview EGPRS 11

1.3 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 431.13 GPRS Channel Coding 451.14 EGPRS Channel Coding 48

1.15 Radio Link Adaptation Overview 531.16 Automatic ReQuest for repetition (ARQ) 541.17 Type-I ARQ mechanism 551.18 Type-I ARQ in GPRS 561.19 Type-I ARQ in EGPRS 571.20 (E)GPRS radio physical channel: PDCH Concept 611.21 (E)GPRS Multiframe 621.22 (E)GPRS Logical Channels 631.23 Master/Slave PDCH concept 651.24 Temporary Block Flow 661.25 Resources Sharing 681.26 MS multiplexing co-ordination 721.27 GPRS mobility management (GMM) states for MS 751.28 Radio Resource (RR) operating modes for MS 76

1.29 Attach procedure 771.30 PDP context activation 791.31 Location management 801.32 Routing Area 811.33 Network Mode of Operation (NMO) 821.34 TBF establishment 831.35 UL TBF establishment on CCCH, 1 phase access 841.35 UL TBF establishment on CCCH, 1 phase access 851.36 UL TBF establishment on CCCH, 2 phases access 861.37 DL TBF establishment on CCCH 881.38 System information broadcasting on BCCH 891.39 System information broadcasting on PBCCH 911.40 (E)GPRS Transmission Aspects 941.40 TRX Classes Concept 95

1.41 Two Abis Links per BTS 982 Features 99

2.1 Enhanced Packet Cell Reselection (R4 MSs) 1002.1.1 Radio Network Impact 101

2.2 Extended Uplink TBF Mode 1022.2 Radio Network Planning Impact 1032.3 Enhanced support of E-GPRS (EDGE) in uplink 105

2.3.1 Radio Network Planning Impact 1072.4 Counter Improvements for Release B9 108

2.4.1 Radio Network Planning Impact 112


6/328


TMO54048 Edition 2




1 1 6

Table of Contents [cont.]


2.5 Autonomous Packet Resource Allocation 1132.5.1 Radio Network Planning Impact 115

2.6 2G/3G Inter-working 116

2.6.1 Radio Network Planning Impact 1192.7 M-EGCH Statistical Multiplexing 120

2.7.1 Radio Network Planning Impact 1222.8 Dynamic Abis allocation 123

2.8.1 Radio Network Planning Impact 1242.9 Enhanced transmission resource management 1252.10 RMS_I1 Improvements 126

2.10.1 Radio Network Planning Impact 1272.11 RMS_I2 Improvements 128

2.11.1 Radio Network Planning Impact 1293 (E)GPRS Radio Algorithms 131

3.1 Cell Reselection Overview 1323.2 Cell reselection: NC0 mode, no PBCCH established 1363.3 Cell reselection: NC0 mode, PBCCH established 138

3.4 Cell reselection execution: NC0 in PTM 1453.5 Cell reselection: NC2 mode 1473.6 GPRS redirection 1583.7 GPRS Power Control: Overview 1603.8 GPRS Power Control: Measurements 1613.9 GPRS Power Control: Algorithm 1653.10 Link adaptation: DL GPRS Radio Link Control 1683.11 Link adaptation: UL GPRS Radio Link Control 1723.12 Link adaptation in EGPRS: New metrics 1753.13 Link adaptation: DL EGPRS Radio Link Control 1763.14 EGPRS Link Adaptation Decision 1783.15 TRX ranking/TRX transmission pool set-up 1793.16 TRX capability for PS traffic 1813.17 Radio Resource Allocation: Overview 182

3.18 Radio Resource Allocation: PDCH state 1833.19 TRX selection for EGPRS TBFs 1863.20 Radio Resource Allocation: EGPRS TBFs 1913.21 Radio Resource Allocation: TBF Re-allocation 1943.22 Radio Resource Allocation: Min_PDCH 1953.23 Radio Resource Allocation: Fast initial (E)GPRS access 196

4 General (E)GPRS planning principels 1974.1 Throughput Dependency -> Interference (and Level) 1984.2 Packet data throughput 1994.3 Reference performance point 2004.4 Saturation effect 2014.5 Cell area and throughput 2034.6 Throughput C/I 204

5 (E)GPRS Network introduction 207

5.1 GPRS network planning 2085.2 GPRS Greenfield planning 2095.3 GPRS traffic calculation and traffic analysis 2115.4 GPRS traffic calculationand PS traffic 2125.5 GPRS traffic calculation and user profile 2145.6 GPRS traffic calculation and market applications 2155.7 GPRS traffic calculation and user behavior 2165.8 Customer questionnaire 2175.9 Traffic Model (Example) 2195.10 User mapping 2205.11 Multi-Service 2215.12 QoS per User Application 2225.13 GPRS traffic calculation 2235.14 Exemplary results of the 3 traffic calculation methods 228

5.15 GPRS traffic calculation result 233


7/328


TMO54048 Edition 2




1 1 7

Table of Contents [cont.]


6 (E)GPRS Network design 2356.1 General 2366.2 Frequency planning 239

6.3 Throughput 2416.4 Link budget 2426.5 Interference analysis on BCCH frequencies 2456.6 Interference analysis on TCH frequencies 2466.7 TRX assignment to GPRS service 2476.8 GPRS Analysis 2486.9 LA and RA planning 2526.10 Quality of Service 262

7 Considerable features to react (E)GPRS target 2657.1 General 2667.1 Optimization campaign on parameters 2677.2 MPDCH 2687.3 Enhanced PDCH Adaptation & Fast pre-emption 2717.4 User multiplexing 272

7.5 PDCH Resource Multiplexing 2737.6 Radio (TBF) Resource Reallocation 2747.7 Coding Scheme Adaptation 2767.8 Cell Reselection 2777.8 GPRS Power Control 2797.8 Features on DL TBF establishment and release 280

7.8.1 Delayed DL TBF release 2817.8.2 Fast Downlink TBF re-establishment process 2837.8.3 Non-DRX feature 284

8 GPRS introduction into operational GSM network 2858.1 General 286

9 GSM Network enhancement features & GPRS 2939.1 Frequency Hopping 2949.2 -cell 296

9.3 Dual Band 2989.4 Concentric cell 301

10 E-GPRS 30310.1 E-GPRS main differences 304

11 GPRS traffic calculation example 30711.2 User and area distribution determination 31011.3 Traffic demand for CS traffic 31111.4 Traffic demand for packet traffic 31211.5 Network capacity calculation 31611.6 Traffic dimensioning 320


8/328


TMO54048 Edition 2




1 1 8

Blank Page

This page is left blank intentionally


9/328


TMO54048 Edition 2



All Rights Reserved Alcatel-Lucent 2007E-GPRS RNP (Radio Network Planning) B10

Fundamentals

1 1 9

1 Basics


10/328


TMO54048 Edition 2




Fundamentals

1 1 10

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


11/328


TMO54048 Edition 2




Fundamentals

1 1 11

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 of8-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 3bits instead of 1 bit in GMSK increased data rates


12/328


TMO54048 Edition 2




Fundamentals

1 1 12

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 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-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).


13/328


TMO54048 Edition 2




Fundamentals

1 1 13

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 thecoverage 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 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).


14/328


TMO54048 Edition 2




Fundamentals

1 1 14

1 Basics

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 radioresources for PS traffic.

Single slot operation DTM MSs are not supported in Alcatel BSSbecause 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.


15/328


TMO54048 Edition 2




Fundamentals

1 1 15

1 Basics

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 half

rate 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 the

macro 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.


16/328


TMO54048 Edition 2




Fundamentals

1 1 16

1 Basic

1.5 (E)GPRS MS Multislot Classes

Multislot

Class1 2 3 4 5 6 7 8 9 10 1 1 12 1 3 14 1 5 1 6 1 7 18 1 9 20 2 1 22 2 3 2 4 2 5 26 2 7 28 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

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 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

(check also P.323)

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.


17/328


TMO54048 Edition 2




Fundamentals

1 1 17

1 Basics

1.6 (E)GPRS General Architecture

(E)GPRS defines a network architecture dedicated to packet servicedomain, with radio access, which allows service subscriber to sendand 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


18/328


TMO54048 Edition 2




Fundamentals

1 1 18

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

AInterface

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).


19/328


TMO54048 Edition 2




Fundamentals

1 1 19

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.


20/328


TMO54048 Edition 2




Fundamentals

1 1 20

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


21/328


TMO54048 Edition 2




Fundamentals

1 1 21

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 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


22/328


TMO54048 Edition 2




Fundamentals

1 1 22

1 Basics

1.8 (E)GPRS Protocol Layers (Transmission Plane)

NSNetwork ServiceGSM 08.16

RLCRadio Link Control

GSM 04.60

httpHypertext Transfer

Protocol

relay

MACMediumAccess

ControlGSM 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

ProtocolGSM 09.60

Gn GGSN

SNDCPSubnetworkDependent

ConvergenceProtocol

GSM 04.65

Ethernet

FR

Frame Relay

ATMAsynchronous

Transfer Mode

E1 (PCM30)G.703 / G.704

Gi

relay

relay


ProtocolRFC 793

RLCRadio Link Control

GSM 04.60

MACMediumAccess

ControlGSM 04.60

L1-GCHLayer 1 GPRS

Channel

L2-GCHLayer 2 GPRS

Channel

NSNetwork ServiceGSM 08.16

BSSGPBSS GPRS Protocol

GSM 08.18

LLCLogical Link Control

GSM 04.64

SNDCPSubnetworkDependent

ConvergenceProtocol

GSM 04.65

IPInternet Protocol

RFC 791

GTPGPRS Tunneling

ProtocolGSM 09.60

IPInternet Protocol

RFC 791

and/or:

or:

UDPUser Datagram

ProtocolRFC 768


ProtocolRFC 793

or:

Ethernet

FR

Frame Relay

ATMAsynchronous

Transfer Mode

E1 (PCM30)G.703 / G.704

IPInternet Protocol

RFC 791

and/or:

or:

Applicationexample

wwwWorld Wide Web

Physical

RF Layer

Physical

Link Layer

Physical

RF Layer

L1bisLayer 1bisGSM 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.


23/328


TMO54048 Edition 2




Fundamentals

1 1 23

1 Basics

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


24/328


TMO54048 Edition 2




Fundamentals

1 1 24

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

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

IdB

(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 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 3/5.2seconds (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 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 + 348encrypted 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


25/328


TMO54048 Edition 2




Fundamentals

1 1 25

1 Basics

1.11 8-PSK TRA Power Aspects

TRA GMSK output power 8-PSK output power

900 MP 45 W / 46.5 dBm 15 W / 41.8 dBm

900 HP 60 W / 47.8 dBm 25 W / 44 dBm

1800 MP 35 W / 45.4 dBm 12 W / 40.8 dBm

1800 MP 60 W / 47.8 dBm 25 W / 44 dBm

900 EDGE+ 45 W / 46.5 dBm 30 W / 44.8 dBm

1800 EDGE+ 35 W / 45.4 dBm 30W / 44.8 dBm

Nominal output power (PN) of the transmitter represents theaverage 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.


26/328


TMO54048 Edition 2




Fundamentals

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_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 theBS_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

SECTORGMSK

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 differencebetween 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 takeninto account in the link adaptation tables.


27/328


TMO54048 Edition 2




Fundamentals

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 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)


28/328


TMO54048 Edition 2




Fundamentals

1 1 28

1 Basics


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: BCCHfrequency shall usually be transmitted at a constant level. A tolerance has beenintroduced with 8-PSK: a fluctuation ofup to 2 dB is allowed If APD isgreater than 2 dB, a static power attenuation should be applied or EGPRS capabilityshould 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 inthe 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 celllevel 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


29/328


TMO54048 Edition 2




Fundamentals

1 1 29

Reminder : limitation of B8 Release

The BTS is levelling the output power of each TRE on a sector basis.

The level of output power, on a frequency band basis, is adapted to the lower TRE

output in the sector after coupling(s).

For example, if a sector is configured with a TRGM (35W) and a TRAG (45W), the

output power of the sector is automatically levelled to 35W.

1 Basics

Unbalancing TRX Output Power per BTS sector

Introduction (1 / 3)


30/328


TMO54048 Edition 2




Fundamentals

1 1 30

Reminder : coupling stage

Antenna coupling is the stage which handles

combining functions as well interface withthe antennas.

Antenna Network Combiner (ANc) performs

these functions for up to 4 TRXs.

As shown in the figure, if the

by-pass function is used (up to 2 TRX),

the TRE signal doesnt suffer the 3dB

attenuation.

For configurations of higher capacity (more

than 4 TRX), a combiner stage can be added

(ANY)

1 Basics


S plitter S plitterW BC

TR X 1

TX RX n RX d

TR X 2

TX RX n RX d


TR X 3

TX RX n RX d

TR X 4

TX RX n RX d

TXA R XA R XdivA R Xd ivBR XBT XB


TR X 1

TX RX n RX d

TR X 2

TX RX n RX d


TR X 3

TX RX n RX d

TR X 4

TX RX n RX d

S plitterS plitter S plitterS plitterW BCW BC

TR X 1

TX RX n RX d

TR X 1

TX RX n RX d

TR X 2

TX RX n RX d

TR X 2

TX RX n RX d

S plitterS plitter S plitterS plitterW BCW BC

TR X 3

TX RX n RX d

TR X 3

TX RX n RX d

TR X 4

TX RX n RX d

TR X 4

TX RX n RX d

TXA R XA R XdivA R Xd ivBR XBT XB

Antenna ATXA - RXA -RXdivB

SplitterWBC

TRX 1

TX RXnR Xd

TRX 2

TXRXnRXd

Splitter

Splitter

LNA

Duplexer

FilterFilter

Splitter Splitter WBC

Antenna BTXB-RXB -RXdivA

Duplexer

FilterFilter

Splitter

LNA

-1 dB

-3 dB

By-pass By-pass



31/328


TMO54048 Edition 2




Fundamentals

1 1 31

Reminder : coupling stage

As the lowest TRE output power definesthe final one on the sector, in case of

un-symetric configuration, the more

coupled stage influences the less one.

This is shown on the example here,

when adding a 3rd TRX (the by-pass

function is removed on both sides)

The 3dB loss impacts all TRX

of the cell

1 Basics


Antenna ATXA -RXA - RXdivB

SplitterWBC

TRX 1TXRXnRXd

TRX 2TXRXnRXd

Splitter

Splitter

LNA

Duplexer

FilterFilter

Splitter Splitter WBC

Antenna BTXB- RXB - RXdivA

Duplexer

FilterFilter

Splitter

LNA

TRX 3TXRXnRXd



32/328


TMO54048 Edition 2




Fundamentals

1 1 32

Two options available in B9: As of before : Balanced Configuration One single output power for all TRX in the same band

New Alternative : Unbalanced Configuration

Goal of the new Unbalanced Configuration: Benefit of higher output power for coverage gap/ better indoor penetration Benefit of the higher power provided by latest TRX versions

Principle : 2 output power levels in the cell Based on the concentric cell principle The cell is declared as a concentric cell

Automatic mapping ofTRE of highest power in the outer zone

1 Basics


Description of the new feature


33/328


TMO54048 Edition 2




Fundamentals

1 1 33

Unbalanced TRX Output Power in B9

The principle of the feature is to define a specific concentric cell in which the outputpower balancing is performed on a zone basis instead of sector basis.

When the feature is activated, the BSS system ensures that the more powerful TREs aremapped on TRX configured on the outer zone, and the less powerful ones, on the TRXconfigured on the inner zone.

Pre-requisitesThe cell is of type concentric mono-band

The cell is not shared

BenefitsAllows a smooth introduction of High Power GMSK (e-g better coverage, without

replacing all TREsUpgrade of 2 TRXs / cell in by-pass mode towards 3 TRXs w/o impact on coverage and

w/o need of Low Loss Configuration (higher CAPEX)

1 Basics


Description of the new feature (1 / 3)


34/328


TMO54048 Edition 2




Fundamentals

1 1 34

Specificities of concentric cells

A concentric cell is a cell made of two virtual zones : one Inner and one Outer A group of TREs transmits with higher power (Outer Zone), while the other group transmits with

lower power (Inner Zone). All the TREs work on the same band and cover the same cell.

There is only one BCCH, and it must be managed by the group of TREs of higher power in order to

guarantee the coverage of both zones.

1 Basics




35/328


TMO54048 Edition 2




Fundamentals

1 1 35

Feature activation Activated at OMC through a new parameter: EN-Unbalanced-Output-Power

When activated, it introduces a new kind of concentric cell. In this cell, thebalancing of the output power will be performed on a zone basis.

The existing current mechanism is kept if the feature not activated.

Algorithm & System impacts The BTS informs the BSC, for each TRE, about the GMSK and 8PSK output power

(after coupling).

The BTS informs the OMC through HW audit about the output power of each TRE forGMSK and 8PSK modulation

When the feature is activated, the BSC maps on the HP TRE the TRX configured by

the operator on the outer zone and on the others the TRX of the inner zone. The information of unbalanced output power activated is transmitted to the BTS by

CDM at sector level. For each TRE, the output power computed by the BSC afterTRX/RSL mapping is also transmitted to the BTS by CDM.

1 Basics




36/328


TMO54048 Edition 2




Fundamentals

1 1 36

1 Basics

Unbalanced TRX Output Power

TRE M P (4 5W) TRE H P (6 0W)

At an tenn a connector 46,5 47,8

Not combined 45,5 46,8

Combined 42,1 43,4

Type o f TRE

Output power in dBm, in GMSK (900 MHz)

ANB

MPHP

60W

Outer zone Inner zone

Without newfeature

With newfeature

Without new feature With new feature

45,5 46,8 45,5-BS_TXPWR_MAX_INNER

45,5

Example 1 :2 TRE not combined1 Medium Power TRX+ 1 High Power TRX

Example 1 :2 TRE not combined1 Medium Power TRX+ 1 High Power TRX

Examples of configurations (1 / 3)


37/328


TMO54048 Edition 2




Fundamentals

1 1 37

1 Basics





Combined 42,1 43,4

Type o f TRE


Example 2 :

3 Trx in mixed mode:2 TRX MP (46,5 dBm)1 TRX HP (47,8 dBm) inByPass

Example 2 :

3 Trx in mixed mode:2 TRX MP (46,5 dBm)1 TRX HP (47,8 dBm) inByPass


Without newfeature

With newfeature



42,1

ANC

MP MP HP

BP



38/328


TMO54048 Edition 2




Fundamentals

1 1 38

1 Basics





Combined 42,1 43,4

Type o f TRE


Example 3 :3 Trx in combined mode:2 TRX HP (47,8 dBm),1 TRX MP (46,5 dBm)

Example 3 :3 Trx in combined mode:2 TRX HP (47,8 dBm),1 TRX MP (46,5 dBm)


Without newfeature

With newfeature



42,1

ANC

HP HP MP



39/328


TMO54048 Edition 2




Fundamentals

1 1 39

1 Basics


HMI name Definition Sub-system

Instance OMC-R access

Range / Defvalue

Recommended rule

EN-Unbalanced-Output-Power

This parameter activates the featureUnbalanced output power on the cell

BSC Cell CAE/Changeable

0-1

Def:0

When the flag is activated;it is recommended to setthe TPM parameter to 0 forall TRX of the outer zone.

Innerzone-Output-Power

This parameter defines the BTS outputpower on the inner zone for aconcentric cell wtih the UnbalancedTRX output power feature activated

BSC Cell CAE/Displayed

0-255

Def:255

Mandatory rule:

This parameter is displayedand meaningfull only if theEn-Unbalanced-Output-Power is set to True

Outerzone-Output-Power

This parameter defines the BTS output

power on the outer zone for a

concentric cell with the,UnbalancedTRX output power feature activated

BSC Cell CAE/Displayed

0-255

Def:255

Mandatory rule:

This parameter is displayedand meaningfull only if theEn-Unbalanced-Output-Power is set to True

TRE-8psk-Capability

This parameter gives the 8PSK powerlevel that a TRE is capable to emit

BSC TRE CAE/Displayed

0-255

Def:255

TRE-GMSK-Capability

This parameter gives the GMSK powerlevel that a TRE is capable to emit

BSC TRE CAE/Displayed

0-255

Def:255

Logical parameters


40/328


TMO54048 Edition 2




Fundamentals

1 1 40

1 Basics


OMC-R parameters view (at cell level)


41/328


TMO54048 Edition 2




Fundamentals

1 1 41

1 Basics


Impact on Counter RMSPw3 (MAX_POWER_PER_TRX)

Counter definition: Maximum GMSK TRX power level applied at the BTSantenna output connector in dBm. The power takes into account thedifferent losses (cables, internal combiners) and the internal/ externallevelling but it does not take into account the BS-TXPWR-MAX, attenuationrequired by the OMC_R.

Impact of the feature: If the feature is activated, the counter shall be set,by the BTS, to the power required by the BSC for the corresponding TRE.(TRE on which the TRX is mapped).

Counters & Indicators impact


42/328


TMO54048 Edition 2




Fundamentals

1 1 42

Impact on RNO indicators

Creation of 2 new indicators in B9, calculated per TRX from the counters RMSPw3 andRMS20. RMS20 provides the band (GMS or DCS) of the TRX.The 2 indicators are expressed in Watts, and defined as follows:

RMS_DL_Power_max_TRX_900:if RMS20= 6 or 2 or 0 (GSM850 or E-GSM or P-GSM)then RMS_DL_Power_max_TRX_900 = log(RMSPW3)else RMS_DL_Power_max_TRX_900 = "0"

RMS_DL_Power_max_TRX_1800:if RMS20= 1 or 3 (DCS1800 or DCS1900)then RMS_DL_Power_max_TRX_1800 = log(RMSPW3)else RMS_DL_Power_max_TRX_1800 = "0"

Both are consolidated at cell level by performing the sum on all TRX.

1 Basics


Counters & Indicators impact


43/328


TMO54048 Edition 2




Fundamentals

1 1 43

1 Basics

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)


44/328


TMO54048 Edition 2




Fundamentals

1 1 44

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


45/328


TMO54048 Edition 2




Fundamentals

1 1 45

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 netto 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


46/328


TMO54048 Edition 2




Fundamentals

1 1 46

1 Basics

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 dependingfrom 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 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)


47/328


TMO54048 Edition 2




Fundamentals

1 1 47

1 Basics

1.13 GPRS Channel Coding [cont.]

Scheme Modulationschemes

Coding schemes

for RLC data block

Coderate

Maximum data rateper TS (RLC payload)

[kbps]

CS-4 GMSK No coding 1.00 20.0

CS-3 GMSK Half rate convolutionalcoding, punctured

0.75 14.4

CS-2 GMSK Half rate convolutionalcoding, punctured

0.66 12.0

CS-1 GMSK Half rate convolutionalcoding

0.50 8.0

8

12

14.4

CS-1

CS-2

CS-3

CS-420

GMSKmodulat ion

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


48/328


TMO54048 Edition 2




Fundamentals

1 1 48

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 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.


49/328


TMO54048 Edition 2




Fundamentals

1 1 49

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, 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


50/328


TMO54048 Edition 2




Fundamentals

1 1 50

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 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 certainCS, 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).


51/328


TMO54048 Edition 2




Fundamentals

1 1 51

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

header E FBIRLC Data Block

= 592 bits BCS TB E FBIRLC 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:


52/328


TMO54048 Edition 2




Fundamentals

1 1 52

1 Basics


Scheme Modulationschemes

Coding schemesfor RLC data block

Coderate

Maximum data rate per TS (RLCpayload)

[kbps]

MCS-9 8PSK 1/3 rate convolutional

coding, punctured

1.00 59.2


coding, punctured

0.92 54.4

MCS-7 8PSK 1/3 rate convolutionalcoding, punctured

0.76 44.8

MCS-6 8PSK 1/3 rate convolutionalcoding, punctured

0.49 29.6


coding, punctured

0.37 22.4

MCS-4 GMSK 1/3 rate convolutionalcoding, punctured

1.00 17.6


0.80 14.8

MCS-2 GMSK 1/3 rate convolutional

coding, punctured

0.66 11.2


0.53 8.8

Uplinktransfer


53/328


TMO54048 Edition 2




Fundamentals

1 1 53

1 Basics

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 ofGPRS TBF mode and

Link Adaptation (LA) in case ofEGPRS 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


54/328


TMO54048 Edition 2




Fundamentals

1 1 54

1 Basics

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)


55/328


TMO54048 Edition 2




Fundamentals

1 1 55

1 Basics

1.17 Type-I ARQ mechanism

In the selective type-I ARQmechanism, the receiver discards theerroneous blocks, and indicates in the acknowledgement messagesthe 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 UplinkAck/Nack /PACCH (3)




The Block 2 has been

unsuccessfully received

MS retransmits the uplinkRLC 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 and in uplink for the EGPRS (B8 release case).

In EGPRS, only type I ARQ applies in uplink (B8 release case). The network implicitly sets the type I mode

by ordering the MS to use a specific MCS and setting the resegment bit to 1 in the Packet UL Ack/Nack

message (resegment bit = 1 indicates to the MS that the retransmitted RLC data block shall be resegmented

according to the commanded MCS (next lowest MCS in the same MCS family than the one used for the initial

block)).


56/328


TMO54048 Edition 2




Fundamentals

1 1 56

1 Basics

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

GPR

SDRAWBACK


57/328


TMO54048 Edition 2




Fundamentals

1 1 57

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 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 withMCS-3. The blocks that are sent for the first time will be transmitted with thelast-ordered MCS


58/328


TMO54048 Edition 2




Fundamentals

1 1 58

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 atthe 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 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 acknowledgedmode.

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).


59/328


TMO54048 Edition 2




Fundamentals

1 1 59

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 blockusing the puncturing scheme P1 andMCS-6. B1 is not successfully

decoded 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 datamaking 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


60/328


TMO54048 Edition 2




Fundamentals

1 1 60

1 Basics


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 firsttransmission 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)


61/328


TMO54048 Edition 2




Fundamentals

1 1 61

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 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


62/328


TMO54048 Edition 2




Fundamentals

1 1 62

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 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


63/328


TMO54048 Edition 2




Fundamentals

1 1 63

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 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)


64/328


TMO54048 Edition 2




Fundamentals

1 1 64

1 Basics

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 As

Date post:	14-Apr-2018
Category:	Documents
Upload:	vijay-verma
View:	220 times
Download:	0 times

Tmo54048_gprs & Egprs Planning_b10

Documents