63314619 E GPRS Radio Networks Planning Theory S13

5/28/2018 63314619 E GPRS Radio Networks Planning Theory S13

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(E)GPRS Radio NetworksPlanning TheoryVersion 3.0



2/166 CMO SBU MSNetwork & Service OptimizationCapability Management

16/12/2008 Copyright 2007 Nokia Siemens Networks.All rights reserved.

DOCUMENT DESCRIPTION

Title and version (E)GPRS Radio Networks - Planning Theory v3.0

ReferenceTarget Group Radio, Tranmission, E2ETechnology andSW release

GERAN - S13

Related ServiceItemsService ItemnumberAuthor Pal SzabadszallasiDateApprover Villa Salomaa

CHANGE RECORD

This section provides a history of changes made to this document

VERSION DATE EDITED BY SECTION/S COMMENTS

1.0 17.06.2005 Pal Szabadszallasi2.0 18.12.2006 Pal Szabadszallasi3.0 16.12.2008 Pal Szabadszallasi

Copyright Nokia Siemens Networks. This material, including documentation and any relatedcomputer programs, is protected by copyright controlled by Nokia Siemens Networks. All rights arereserved. Copying, including reproducing, storing, adapting or translating, any or all of this materialrequires the prior written consent of Nokia Siemens Networks. This material also containsconfidential information which may not be disclosed to others without the prior written consent ofNokia Siemens Networks.





Table of contents

1. Introduction....................................................................................... 7

1.1 (E)GPRS Dimensioning, Planning and Optimization Structure........................................8

1.2 Data hardware and site solutions....................................................................................81.2.1 BSC and PCU variants ...................................................................................................81.2.1.1 PCU2 Plug-in Unit Variants and Hardware Architecture..................................................91.2.1.2 PCU2 Software Architecture.........................................................................................101.2.1.3 PCU1 and PCU2 Software Differences on Air Interface................................................111.2.2 BTS variants.................................................................................................................121.3 Data features................................................................................................................121.3.1 S10 / S10.5ED..............................................................................................................121.3.2 S11 / S11.5...................................................................................................................131.3.3 S12...............................................................................................................................131.4 S13...............................................................................................................................14

2. (E)GPRS Modulation ...................................................................... 152.1 GMSK and 8-PSK Modulation ......................................................................................152.2 Modulation Block Diagrams..........................................................................................162.3 Back-off in EGPRS.......................................................................................................172.4 Burst Structure .............................................................................................................19

3. Coding Schemes ............................................................................ 21

3.1 Protocol Architecture ....................................................................................................213.1.1 Physical Layer ..............................................................................................................223.1.2 RLC/MAC Layer ...........................................................................................................223.1.2.1 Radio Link Control........................................................................................................223.1.2.2 Medium Access Control................................................................................................22

3.1.2.3 RLC/MAC Header Formats...........................................................................................223.1.3 Logical Link Control......................................................................................................273.1.4 SNDCP Layer ...............................................................................................................283.1.5 IP, TCP/UDP and Application Layer .............................................................................283.2 RLC/MAC Coding Schemes .........................................................................................303.2.1 GPRS Coding Schemes (CSs) .....................................................................................303.2.2 EGPRS Modulation and Coding Schemes (MCSs).......................................................33

4. (E)GPRS Procedures......................................................................36

4.1 TBF Establishment .......................................................................................................364.1.1 Channel Request and Packet Immediate Assignment ..................................................364.1.2 DL TBF Assignment .....................................................................................................37

4.1.3 UL TBF Assignment .....................................................................................................394.1.3.1 Channel Request - Packet Access Procedure (CCCH / PCCH)....................................394.1.3.2 EGPRS Packet Channel Request.................................................................................404.1.3.3 Dynamic and Extended Dynamic Allocation on UL with and without USF4...................414.1.3.4 UL TBF ASSIGNMENT, MS on CCCH, 2 phase access...............................................424.1.3.5 UL TBF ASSIGNMENT, MS on CCCH, 1 phase access...............................................434.1.3.6 EGPRS UL TBF ASSIGNMENT, MS on PCCCH with 2 phase access.........................454.1.3.7 EGPRS UL TBF ASSIGNMENT, MS on PCCCH with 1 phase access.........................454.1.3.8 Establishment of EGPRS UL TBF when DL TBF is ongoing.........................................464.2 (E)GPRS Data Transfer................................................................................................474.2.1 (E)GPRS Data Transfer DL ..........................................................................................47





4.2.2 (E)GPRS Data Transfer UL ..........................................................................................474.3 Mobility with Cell-reselection ........................................................................................494.3.1 Intra PCU Cell-Reselection...........................................................................................494.3.2 Inter PCU Cell-reselection (Intra BSC)..........................................................................504.3.3 RA/LA Update (intra PAPU)..........................................................................................51

4.3.4 RA/LA Update (Inter PAPU or inter SGSN)...................................................................524.4 TBF Release ................................................................................................................534.4.1 Packet TBF Release Content .......................................................................................544.4.2 Abnormal Releases ......................................................................................................544.4.3 TBF Release in PCU2 ..................................................................................................55

5. (E)GPRS Accessibility .................................................................... 56

5.1 Air Interface Signaling Load..........................................................................................565.1.1 Common Control Channels ..........................................................................................575.1.1.1 Paging Channel............................................................................................................575.1.1.2 Access Grand Channel.................................................................................................575.1.1.3 Random Access Channel .............................................................................................58

5.1.2 SDCCH ........................................................................................................................585.2 TRXSIG Load ...............................................................................................................595.2.1 TRXSIG Load Theory ...................................................................................................595.2.1.1 Abis Protocols ..............................................................................................................595.2.1.2 TRXSIG Load Components, Measurement and Analysis..............................................615.3 BCSU Load ..................................................................................................................645.3.1 BSC RAW Measurement Results .................................................................................645.3.2 Reporting Suit 184 Report ............................................................................................645.4 Signaling Load with DTM Usage...................................................................................65

6. Resource Allocation in BSS ............................................................ 66

6.1 Cell Reselection............................................................................................................67

6.1.1 C1 and C2 ....................................................................................................................676.1.2 C31/C32.......................................................................................................................686.1.3 Network Controlled Cell Reselection.............................................................................716.1.3.1 NCCR Benefits .............................................................................................................726.1.3.2 NCCR Functionality......................................................................................................726.1.3.3 Target cell selection......................................................................................................736.1.3.4 Signaling Flow..............................................................................................................746.1.3.5 BLER Limits are Needed for the Quality Control Function in PCU2 ..............................756.2 BTS Selection...............................................................................................................766.2.1 Initial BTS Selection .....................................................................................................766.2.2 BTS Selection for Reallocating TBF..............................................................................796.2.2.1 Uplink Rx Lev Reallocation...........................................................................................816.2.2.2 Downlink Rx Lev Reallocation ......................................................................................82

6.2.2.3 Downlink RX Lev Received First Time Reallocation .................... .................................826.2.2.4 BTS Selection in PCU2.................................................................................................826.2.2.5 Territory Upgrade Request in PCU2 ............................................................................. 836.3 Channel Scheduling .....................................................................................................846.3.1 Priority based Quality of Service...................................................................................846.3.2 Channel Allocation........................................................................................................856.3.3 TBF Scheduling ............................................................................................................866.3.4 QoS Information Delivery..............................................................................................876.3.5 Nokia HLR QoS Settings ..............................................................................................886.4 Flow Control on Gb.......................................................................................................916.5 Gb over IP ....................................................................................................................91





7. (E)GPRS Timeslot Data Rate ......................................................... 93

7.1 GSM Network Performance..........................................................................................937.1.1 Impact of Coverage Level.............................................................................................937.1.1.1 Signal Strength Requirements......................................................................................94

7.1.1.2 Receiving End ..............................................................................................................957.1.1.3 Measurement Results...................................................................................................967.1.2 Impact of Interference Level .........................................................................................987.1.2.1 Simulation Results........................................................................................................987.1.2.2 Spectrum Efficiency and Frequency Reuse .......... ......................................................1037.1.2.3 Measurement Results.................................................................................................1047.1.3 Mixture of Signal Level and Interference.....................................................................1047.2 TSL Utilization Improvement.......................................................................................1067.2.1 Acknowledge Request Parameters.............................................................................1067.2.1.1 GPRS DL/UL Penalty and Threshold..........................................................................1067.2.1.2 (E)GPRS DL/UL Penalty and Threshold.....................................................................1067.2.2 PRE_EMPTIVE_TRANSMISSIO................................................................................1077.3 TBF Release Delay Parameters (S10.5 ED)...............................................................107

7.3.1 DL_TBF_RELEASE_DELAY ......................................................................................1077.3.2 DL_TBF_RELEASE_DELAY in PCU2........................................................................1087.3.3 UL_TBF_RELEASE_DELAY ......................................................................................1087.3.4 Release of downlink Temporary Block Flow ...............................................................1097.3.5 Release of uplink Temporary Block Flow....................................................................1097.4 TBF Release Delay Extended (S11 onwards).............................................................1107.4.1 TBF is Continued based on EUTM .............................................................................1107.4.2 TBF is Not Continued based on EUTM.......................................................................1117.4.3 EUTM in PCU2...........................................................................................................1127.5 BS_CV_MAX..............................................................................................................1127.6 GPRS and EGPRS Link Adaptation............................................................................1157.6.1 GPRS Link Adaptation (S11) ......................................................................................1157.6.2 GPRS Link Adaptation with CS1-4 (PCU2).................................................................116

7.6.2.1 Link Adaptation Algorithm Used in Uplink Direction ..................... ...............................1187.6.3 EGPRS Link Adaptation with Incremental Redundancy..............................................1217.6.3.1 Link Adaptation Introduction .......................................................................................1217.6.3.2 MCS Selection............................................................................................................1237.6.3.3 Bit Error Probability.....................................................................................................1257.6.3.4 Link Adaptation Procedure .........................................................................................1317.6.3.5 Incremental Redundancy in EGPRS...........................................................................1387.6.3.6 MCS Selection Based on BLER Limits .......................................................................1427.6.3.7 EGPRS LA in PCU2 ...................................................................................................1437.7 Multiplexing ................................................................................................................1447.7.1 Synchronization..........................................................................................................1447.7.2 Dynamic Allocation on UL...........................................................................................1447.7.2.1 GPRS and EGPRS Dynamic Allocation......................................................................144

7.7.2.2 GPRS and EGPRS Dynamic Allocation without USF4...............................................1457.7.2.3 GPRS and EGPRS Dynamic Allocation with USF4.....................................................1457.7.2.4 GPRS and EGPRS Extended Dynamic Allocation with/without USF4.........................146

8. (E)GPRS Territory Settings........................................................... 147

8.1 Timeslot Allocation between Circuit Switched and (E)GPRS Services........................1478.1.1 PSW Territory.............................................................................................................1478.1.1.1 Dedicated (E)GPRS Capacity.....................................................................................1478.1.1.2 Default GPRS Capacity ..............................................................................................1488.1.1.3 Additional (E)GPRS Capacity .....................................................................................148





8.1.2 CSW Territory.............................................................................................................1488.1.2.1 Free Timeslots............................................................................................................1498.1.3 Territory Upgrade/Downgrade Dynamic Variation of Timeslots................................1518.1.3.1 Downgrade.................................................................................................................1518.1.3.2 Upgrade .....................................................................................................................152

8.1.3.3 Territory Upgrade and Downgrade S10 Changes ....................................................... 1528.1.3.4 Multislot TSL Allocation for Using max Capability of Mobile........................................1538.2 Multislot Usage...........................................................................................................1538.2.1 Average Window Size ................................................................................................1558.3 High Multislot Class (HMC).........................................................................................155

9. Mobility ......................................................................................... 157

9.1 Intra/Inter PCU Cell Re-selection................................................................................1579.1.1 BSS and Data Outage................................................................................................1579.1.1.1 BSS Cell-reselection outage.......................................................................................1589.1.1.2 Data outage................................................................................................................1589.1.2 Benchmark Results ....................................................................................................160

9.2 LA /RA Cell-reselection...............................................................................................1619.2.1 Data Outage...............................................................................................................1619.2.1.1 Location Area Update.................................................................................................1619.2.1.2 Routing Area Update ..................................................................................................1619.2.1.3 Data outage (LA/RA Update)......................................................................................1619.2.2 Benchmark Results ....................................................................................................1639.3 Cell-reselect Hysteresis..............................................................................................1649.4 Network Assisted Cell Change ...................................................................................165





1. Introduction

The (E)GPRS Radio Networks Planning Theory document was prepared to providethe basic theoretical knowledge for (E)GPRS Radio Network dimensioning, planningand optimization. The (E)GPRS Radio Networks planning document set structure

listed below:

(E)GPRS Radio Networks Planning Theory

(E)GPRS Radio Networks Dimensioning and Planning Guidelines

(E)GPRS Radio Networks Optimization Guidelines

The Planning Theory gives the theoretical knowledge while Dimensioning andPlanning Guidelines and Optimization Guidelines contain all the practicalinformation for daily planning and optimization activities.

The materials listed above are based on S10.5 ED, S11, S11.5, S12 and S13 BSS

software releases; moreover both PCU1 and PCU2 are taken into account.

The detailed Abis, EDAP, PCU and Gb planning theory are not included in thisdocument. For more information pls. see the latest guidelines on the links below:

GSM Access:

https://sharenet-ims.inside.nokiasiemensnetworks.com/Open/358201395

MW Radio Transmission (and Mobile Backhaul)


GERAN Radio


The 3GPP specifications can be found at the following intranet location:

http://www.3gpp.org/specification-numbering





1.1 (E)GPRS Dimensioning, Planning and OptimizationStructure

The general way of (E)GPRS radio dimensioning, planning and optimizationprocedure is listed below:

(E)GPRS Dimensioning and Planning

Operators business plan investigation

Operators BSS network structure audit (with core network)

Deployment plan preparation

Capacity calculations based on deployment plan

Parameter setting

(E)GPRS Optimization

Configuration and feature audit

BSS and E2E Performance measurements

GSM network optimization

(E)GPRS network optimization

All the points above are described in (E)GPRS Radio Networks - Dimensioning andPlanning Guidelines and (E)GPRS Radio Networks - Optimization Guidelines.

(E)GPRS Radio Networks - Dimensioning and Planning Guidelines:


(E)GPRS Radio Networks - Optimization Guidelines:


1.2 Data hardware and site solutions

The following sessions describe the PS related hardware elements in the BSS chain.

1.2.1 BSC and PCU variants

Nokia Packet Control Unit (PCU) is a Plug-in unit in a Base Station Controller (BSC).PCU hardware is embedded in BSCs in every BCSU (BSC Signaling unit).

The Nokia PCU product family consists of following products:





PCU variant BSC Type Release BSS11

BSS11.5

ownwards

BTS 64 64

TRX 128 128

Radio TSLs 256 128

Abis 16 kbps channels 256 256

Gb 64 kbps channels 31 31BTS 64 64

TRX 128 128

Radio TSLs 256 128


Gb 64 kbps channels 31 31

BTS 64 64

TRX 128 128

Radio TSLs 256 256


Gb 64 kbps channels 31 31

BTS N/A 128

TRX N/A 256

Radio TSLs N/A 256

Abis 16 kbps channels N/A 256

Gb 64 kbps channels N/A 31

BTS 2 x 64 2 x 64

TRX 2 x 128 2 x 128

Radio TSLs 2 x 256 2 x 256

Abis 16 kbps channels 2 x 256 2 x 256

Gb 64 kbps channels 2 x 31 2 x 31

BTS N/A 2 x 128

TRX N/A 2 x 256

Radio TSLs N/A 2 x 256

Abis 16 kbps channels N/A 2 x 256

Gb 64 kbps channels N/A 2 x 31

PCU2-D BSC3i

PCU2-U

PCU-T BSCE, BSC2,

BSCi, BSC2i

BSCE, BSC2,

BSCi, BSC2i

PCU-B BSC3i

PCU BSCE, BSC2,

BSCi, BSC2i

PCU-S BSCE, BSC2,

BSCi, BSC2i

Table 1 PCU product family

The PCU-S is the first and PCU-T the second evolution of PCU variant having morememory and higher CPU clock rate.

1.2.1.1 PCU2 Plug-in Unit Variants and Hardware ArchitectureIn the PCU2 solution, there are two PCU2 plug-in unit variants which implement thenew hardware architecture. PCU2-D is used for BSC3i, which includes two logicalPCU2 units, and PCU2-U is used for the older BSC versions. For more information onthe PCU2 plug-in unit variants, see the PCU2 hardware plug-in unit descriptions inBSC/TCSM documentation.

PCU2 introduces more processing capacity for both PowerQuicc II (PQII) and digitalsignal processors (DSP) with external memory and hardware architectureenhancements to create a basis for new packet data related functionalities.

The functionalities include enhancements in following areas:

Enhanced processing capabilities for PQII and DSPs with external memoryand a higher DSP-level Abis channel connectivity to fully support thesoftware architecture enhancements

Actual traffic and O&M information separated on different paths betweenPQII and DSPs





Figure 1 Main hardware blocks in the PCU1 and PCU2 variants

1.2.1.2 PCU2 Software ArchitectureThe new software architecture, with its modular decomposition and restructured taskmanagement, uses the hardware architecture changes to provide a basis for thenew packet data related functionalities.

With PCU2, the DSPs take care of more tasks than in PCU1. The tasks includeradio link control(RLC), scheduling, quality control, as well as Abis L1 processing.With PCU1, the DSPs only take care of the Abis L1 processing.

Figure 2 Restructured task management in PCU2

The PCU2s new software architecture introduces enhancements in the followingareas:

The RLC, Scheduler, and Quality control functionalities implemented on theDSPs improve the RTT and balances load between PQII and DSPs.





The asynchronous data transfer of LLC PDUs, which is used instead of thesynchronous transfer of RLC/MAC blocks between PQII and DSP, reduces theload in the PQII DSP interface and provides faster PQII DSP transactions.

Increased BTS and TRX resources: with PCU2, the BTS resources are

increased from 64 to 128, and the TRX resources extended from 128 to 256,consequently providing more flexibility to the segment concept used with Multi-BCF Control and Common BCCH.

The new GPRS link adaptation algorithm enables the support for the GPRScoding schemes 3 and 4 (CS3&CS4). It also gives the possibility to reach ahigher throughput per subscriber when the GPRS coding schemes 3 and 4 areused.

The use of uplink state flag (USF) granularity 4 improves the use of the radiointerface resources in a situation where the GPRS and EGPRS mobiles are inthe same radio time-slot (RTSL).

Dynamic Abis improvements, which enable a more efficient use of EDAPs.The recommended number of EDAPs in PCU1 is 1, 2, 4 or 8. Recommendednumber of EDAPs is in PCU2 is 1-8.

Improved end user service perception: The PCU2 software architectureimplements RLC on DSPs and, depending on the radio conditions, givesbenefit to application level delays i.e. active and idle RTTs. The active RTTmeasures delay from the data transfer point of view has an impact for exampleon the duration of file downloads experienced by the end users as well as onservices with fast interaction requirements. The idle RTT measures delay fromthe access point of view, that is, the impact to TCP startup, improves on itspart the end user experience for example in downloading web pages.

BTS selection improvements in case of Common BCCH / Multi BCF cell

Dynamic Abis improvements

PCU2 doesnt provide support for following functionalities available with PCU1:

PBCCH/PCCCH

GPRS support for InSite BTS

1.2.1.3 PCU1 and PCU2 Software Differences on Air InterfaceDue to different feature set and software architecture between PCU generations,there are multiple differences concerning to Air interface. These differences have

influences to radio resource allocation and scheduling, round-trip time, throughputand cell change times.

The most important differences are:

New GPRS link adaptation algorithm in the PCU2 that can use CS-3 and CS-4, too

Utilization of USF granularity 4 in the PCU2

BTS selection differences





Inter DSP TBF reallocation and cell change in the PCU2

The detailed description of the most important differences can be found in therelevant chapters below in this document.

1.2.2 BTS variantsTALK InSite** PrimeSite MetroSite UltraSite FlexiEDGE

GSM Ok Ok Ok Ok Ok Ok

GPRS CS1 2 CS1 2 CS1 - 2 CS1 2* CS1-2* CS1-2*

EGPRS No No No MCS1-9 MCS1-9 MCS1-9

*CS1-4 with PCU2**Insite is not supported by PCU2

1.3 Data features

The next sessions describe the most important PS features on S release basis.

1.3.1 S10 / S10.5ED

The following features are implemented with S10/S10.5ED releases:

BSS 10091 Enhanced Data Rates for Global Evolution, EDGE

Detailed description of GPRS and EGPRS dimensioning and planning is available in(E)GPRS Radio Networks - Dimensioning and Planning Guidelines:

https://sharenet-ims.inside.nokiasiemensnetworks.com/Download/362642110

Detailed description of GPRS and EGPRS optimization is available in (E)GPRS RadioNetworks - Optimization Guidelines


BSS 10045 Dynamic Abis Allocation


BSS 10074 Support of PCCCH/PBCCH

Support for PBCCH/PCCCH is no longer supported from S13 onwards.

BSS 10084 Priority Class Based Quality of Service

With Priority Based Scheduling, an operator can give users different priorities. Higherpriority users will get better service than lower priority users. There will be no extrablocking to any user, only the experienced service quality changes.

The concept of Priority Class is based on a combination of the GPRS Delay class andGPRS Precedence class values. Packets will be evenly scattered within the (E)GPRS





territory between different time slots. After that packets with a higher priority are sentbefore packets that have a lower priority.

The description of priority based QoS is available in (E)GPRS Radio Networks -Optimization Guidelines


1.3.2 S11 / S11.5

The following features are implemented with S11/S11.5 releases:

BSS 11112 Network Controlled Cell Reselection (NCCR)

BSS 11506 Network Assisted Cell Change (NACC)

BSS 115171 Dynamic Abis Enhancements

BSS 11088 GPRS Coding Schemes CS3 and CS4

BSS 30065 GPRS Resume

BSS 11151 Extended Uplink TBF

BSS 11156 EGPRS: Channel Request on CCCH

The detailed description of below listed features are (E)GPRS Radio Networks -Dimensioning and Planning Guidelines:https://sharenet-ims.inside.nokiasiemensnetworks.com/Download/362642110

(E)GPRS Radio Networks - Optimization Guidelines:


1.3.3 S12

The following features are implemented with S12 release:

BSS 20088 Dual Transfer Mode (DTM)

Dual Transfer Mode (DTM) provides mobile users with simultaneous circuit-switched(CS) voice and packet-switched (PS) data services. This means that users can, for

example, send and receive e-mail during an ongoing phone call.

The Planning Theory of DTM can be downloaded from the following link:


Information about DTM planning is available in DTM Planning guidelines:






BSS 20084 High Multislot Classes (HMC)

More information about HMC is available in the (E)GPRS Radio Networks -Optimization Guidelines:


BSS 20089 Extended Dynamic Allocation (EDA)

More information about EDA is available in Chapter 7.7.2.

1.4 S13

The following feature is implemented with S13 releases:

BSS20094 Extended Cell for GPRS/EDGE

More information is available in extended cell range and Long Reach timeslot planningguidelines:






2. (E)GPRS Modulation

(E)GPRS uses not only GMSK but 8PSK (8 Phase Shift Keying) modulation as well,producing a 3bit word for every change in carrier phase. This effectively triples thedata rate offered by GPRS.

The differences between GMSK and 8-PSK, the block diagram of modulators, and theburst structure with back-off are described below in this chapter.

2.1 GMSK and 8-PSK Modulation

GSM system is using GMSK (Gaussian Minimum Shift Keying), a constant-envelopemodulation scheme. The advantage of the constant envelope modulation is that itallows the transmitter power amplifiers to be operated in a non-linear (saturated)mode, offering high power efficiency. The saturation means that even if the inputsignal level is increased, no increasement will be seen in the output power, as shownon upper part of Figure 3.

8-PSK, in the form used in EDGE, has a varying envelope, see the lower part ofFigure 3. It means that the amplifier must be operated in the linear region in case of 8-PSK since distortion is to be avoided. (There is an additional 22.5 deg rotation toavoid zero crossing.)

GMSK

8PSK(0,0,1)

(1,0,1)

(0,0,0)(0,1,0)

(0,1,1)

(1,1,1)

(1,1,0)

(1,0,0)

Time

Envelope (amplitude)

Time


GMSK

8PSK(0,0,1)

(1,0,1)

(0,0,0)(0,1,0)

(0,1,1)

(1,1,1)

(1,1,0)

(1,0,0)

Time


Time


Time


TimeTime


Time


TimeTime


Figure 3 Modulation scheme for GMSK and 8-PSK





2.2 Modulation Block Diagrams

The Figure 4 and Figure 5 show that GMSK and 8-PSK modulation arrangements arecompletely different.

Figure 4 GSM - GMSK modulation

Figure 5 EDGE - 8-PSK modulation

differential

encoding

-1, +1

Gaussian

prefiltering

for frequency

pulses

frequency

modulator

local oscillator

rotation by

k3pi/8

Linearized

Gaussian

Filter

for Dirac

pulses

Gray mapping

to 8PSK

constellation

3 bits per

symbol

I & Q





2.3 Back-off in EGPRS

This varying envelope generates peak-mean power difference that is 2-6 dB for 8-PSK, thus the mean output power in amplifier must be at least this amount down onthe saturated output power to achieve linearity.

Figure 6 Phase state vector diagram in 8-PSK

So the position of the information is there on the yellow dots of the dark blue circleabove in Figure 6 (yellow dots: where the phase and amplitude of the signal iscontaining the information). The area between the dark blue circle and red circle is theroom for overshooting.

This overshoot is required to ensure smooth and continuous transition betweenphase-states (as shown by the yellow trace above).

It means that the mean output power has to be app. 2-6 dB less (back-off) to avoidsaturation in amplifier. This back-off is shown in Figure 7.





GMSK

8PSK

Time


Time


=> Peak to Average of 2-4 dB

Pin

Pout

Back Off= 2 dB

Compression point

Figure 7 Back-off in power amplifier

In practice, BTS equipment is less likely to be in saturation than MS equipment.

Therefore the back-off for the two sets of equipment may be different, and in the linkbudget presented a 2dB back-off is assumed for BTS and the full 4dB for MS. Theamount of MS back-off also depends on the used system frequency (different outputpower, different PA characteristics, etc. 900 MHz: 6dB; 1800 MHz: 4dB).

The UltraSite 2 dB APD and mobiles 4-6 dB applies only when the transmitter is setto maximum output power.

If the entire TRX is set to second highest output power, there is no difference betweenthe average power of 8-PSK and GMSK signals.





2.4 Burst Structure

3GPP TS 05.05, Annex B identifies the following GMSK/8-PSK burst structures fortransmitted power level versus time. The first figure below (Figure 8) shows the timemask for normal duration bursts at GMSK modulation. The second figure (Figure 9)

shows the time mask for normal duration bursts at 8-PSK modulations. The blueenvelope shows a conceptual example of the appearance of a normal burst.

dB

t

- 6

- 30

+ 4

8 s 10 s 10 s 8 s

(147 bits)

7056/13 (542.8) s 10 s

(*)

10 s

- 1+ 1

(***)

(**)

dB

t

- 6

- 30

+ 4

8 s 10 s 10 s 8 s

(147 bits)

7056/13 (542.8) s 10 s

(*)

10 s

- 1+ 1

(***)

(**)

Figure 8 GMSK Burst

10 8 10 10 8 10 t (s)

dB

-30

(*)

-6

+2,4

+4

-20

-2

(***)

(**)

2 2 22

7056/13 (542,8)s

(147 symbols)

0

10 8 10 10 8 10 t (s)

dB

-30

(*)

-6

+2,4

+4

-20

-2

(***)

(**)

2 2 22

7056/13 (542,8)s

(147 symbols)

0

Figure 9 8-PSK Burst

The following figure (Figure 10) shows an example of GSM/EDGE BCCH TRX with a3TSL EDGE mobile active on the downlink 5 normal bursts in GMSK (Average PowerDecrease (APD)=0 dB) and 3 normal bursts in 8-PSK (APD=2 dB).





TSL1TCH

GMSK

TSL2TCH

GMSK

TSL3TCH

GMSK

TSL4TCH

GMSK

TSL5PDTCH8-PSK/GMSK

TSL6PDTCH8-PSK/GMSK

TSL7PDTCH8-PSK/GMSK

TSL0BCCHGMSK

P(dB)

t (us)

Figure 10 5 normal bursts in GMSK (APD=0 dB) for voice and 3 normal bursts in 8-PSK (APD=2 dB) for data

Note that the average power decreased by 2 dB during the last three bursts due toAPD of 2 dB.

This has the following key impacts on EDGE service:

1) Slightly lower throughput near cell edge or in poor C/I environment,

2) 2 dB lower signal level to neighboring cells or GSM phones evaluating neighbors.

If the operator decides to allow 8-PSK modulation on the BCCH carrier in certaincells, the cell selection, cell reselection and handover procedures involving thesecells will be somewhat sub-optimal. This is due to the fact that the signal levelmeasured by the MS at some instances in time will be affected by the possiblylower mean power level of the 8-PSK modulation and by the power fluctuation

resulting from the 8-PSK modulation characteristics.

The extent of the performance degradation is dependent upon the measurementschedule in each particular MS as well as upon the used average power decrease(APD) and the current 8-PSK load. By limiting the maximum number of 8-PSKslots simultaneously allowed on the BCCH carrier, and/or carefully selecting thevalues of involved network parameters, the impact on the above-mentionedprocedures may be minimized. Additionally, in areas with very low cell overlap,some coverage loss effects may have to be taken into account by the operatorwhen selecting network parameters (the measurement of the cell for neighbordecision is based on the average value of TSLs signal level, so the reducedoutput power due to 8-PSK can modify this measurement results).

The power budget margins for handover are around 4/6 dB. This means the signal

strength in the neighbor EGPRS cell has to be 4/6 dB larger than the serving cellin order to perform the handover. Moreover, the mobiles have a certain inaccuracywhen performing neighbor measurements so the impact of average powerdifferences in GMSK and 8PSK will be probably minor.

Note that the average power remains constant since both GMSK and 8-PSK areoperating in the linear range of the PA.





3. Coding Schemes

The following subsections describe the protocol architecture used by (E)GPRS andthe coding schemes for GPRS, GPRS with CS1-4 and EGPRS.

3.1 Protocol Architecture

The following figure shows the different protocols between the different networkelements of a (E)GPRS networks. As it can be seen from Figure 11, the BSS networkrelated protocols are the physical (L1/RF) and RLC/MAC layers. The RLC/MAC, LLCand SNDCP layers are (E)GPRS specific layers, but the higher layers are applicationdependent.

LLC

SNDCP

LLC

SNDCP

L1/RF L1/RF

UmMS BTS

FR

NS

BSSGP

FR

NS

BSSGP

GbSGSN

GTP

UDP

IP

L1

L2

GTP

UDP

IP

L1

L2

GnGGSN

RLC/MAC RLC/MAC

DAbis DAbis

AbisBSC / PCU

IP

L1

L2

WWW/F

Server

Gi

TCP

HTTPorFTP

L1

L2

IPTCP

HTTPor

FTP

Figure 11 (E)GPRS Protocol Stack

The protocols are communicating via Service Access Points (SAP). The Figure 12shows the data block segmentation from IP to GSM RF.

LLC

SNDCP

IP

RLC

MAC

GSM RF

N-PDU

SN-DATA PDU

LLC Frames

RLC Blocks

RLC/MAC Blocks

TDMA Bursts

Figure 12 Data Blocks segmentation between protocols





3.1.1 Physical Layer

The physical layer of the (E)GPRS networks is the standard GSM TDMA interface(with new modulation method for higher MCSs of EGPRS). Therefore the appropriatefunctionality of the GSM network is basic requirement to provide good (E)GPRS

service.

The main tasks of the physical layer are listed below:

Modulation/demodulation (GMSK and 8-PSK)

TDMA frame formatting

Bit inter-leaving

Cell selection/reselection

Tx power control

Discontinuous reception (DRx)

The basic element of air interface in (E)GPRS planning is the timeslot. It lasts 0,577milliseconds (=15/26) which corresponds to 156,25 bits. Four TDMA TSLs areneeded to convey one RLC/MAC block as it can be seen in the Figure 12 above.

3.1.2 RLC/MAC Layer

This subsection briefly describes the Radio Resource layer (RLC/MAC) since thislayer is responsible for most of the important BSS related functionalities.

3.1.2.1 Radio Link ControlThe main tasks of Radio Link Control (RLC) are:

Reliable transmission of data across air interface

Segmentation/de-segmentation of data from/to LLC layer

The RLC layer can be operated in both acknowledged and unacknowledged modes,and this is defined by the Quality of Service (QoS) profile within the PDP context(reliability class).

3.1.2.2 Medium Access ControlThe following list shows the main tasks of Medium Access Control (MAC):

Control of MS access to common air-interface medium

Flagging of PDTCH/PACCH occupancy

This layer controls MS access to the common air interface and provides queuing andscheduling of the associated signaling.

3.1.2.3 RLC/MAC Header FormatsAll the header formats are described below.





The following figure shows the downlink GPRS RLC block with MAC header.

Figure 13 DL RLC/MAC format

Detailed field description:

Uplink State Flag (USF)field is sent in all downlink RLC/MAC blocks and indicatesthe owner or use of the next uplink Radio block on the same timeslot. The USF field isthree bits in length and eight different USF values can be assigned, except onPCCCH, where the value '111' (USF=FREE) indicates that the corresponding uplinkRadio block contains PRACH.

Supplementary/polling (S/P) bit is used to indicate whether the RRBP field is valid ornot.

bit 4 S/P0 RRBP field is not valid

1 RRBP field is valid

Table 2 S/P bit

Relative Reserved Block Period (RRBP) field specifies a single uplink block inwhich mobile station shall transmit either a Packet Control Acknowledgementmessage or a PACCH block to the network. The mobile station shall only react onRLC/MAC block containing a valid RRBP field.





Final Block Indicator (FBI)bit indicates that the downlink RLC data block is the lastRLC data block of the DL TBF.

bit 1 Final block indicator0 Current block is not last RLC data block in TBF

1 Current block is last RLC data block in TBF

Table 3 FBI bit

Power reduction (PR) fields indicate the power level reduction of the current RLCblock. The coding of PR field depends on downlink power control mode mode A andB definedin BTS_PWR_CTRL_MODE bit sent in assignment messages.

Payload Type field shall indicate the type of data contained in remainder ofRLC/MAC block. The encoding of the payload type field is shown below. The payloadType field is present in both downlink and uplink MAC header.

bit8 7

Payload Type

0 0 RLC/MAC block contains an RLC data block

0 1 RLC/MAC block contains an RLC/MAC control blockthat does not include the optional octets of theRLC/MAC control header

10 In the downlink direction, the RLC/MAC block containsan RLC/MAC control block that includes the optionalfirst octet of the RLC/MAC control header.In the uplink direction, this value is reserved.

1 1 Reserved. In this version of the protocol, the mobilestation shall ignore all fields of the RLC/MAC blockexcept for the USF field

Table 4 Payload Type field

Temporary Flow Identity (TFI) field in RLC data blocks identifies the TemporaryBlock Flow (TBF) to which the RLC data belongs. For the downlink and uplink TFI thefield is 5 bits in length and are encoded as a binary number with range 0 to 31.

Block Sequence Number (BSN) field carries the sequence absolute BlockSequence Number (BSN) modulo 128 of each RLC data block within the TBF. TheBSN is 7 bits in length and is encoded as a binary number with range 0 to 127.

The following figure shows the uplink RLC block with MAC header.





Figure 14 UL RLC/MAC format

Detailed field description:

Retry (R) bit shall indicate whether the MS transmitted CHANNEL REQUESTmessage or PACKET CHANNEL REQUEST message one time or more than onetime during its most recent channel access. The mobile station shall send the samevalue for the R bit each uplink RLC/MAC block of the TBF.

bit 1 Retry (R) bit0 MS sent channel request message once

1 MS sent channel request message twice or more

Table 5 Retry bit

The Stall indicator (SI)bit indicates whether the mobile's RLC transmit window canadvance (i.e. is not stalled) or cannot advance (i.e., is stalled). The mobile stationshall set the SI bit in all uplink RLC data blocks.

bit 2 Stall indicator0 MS RLC transmit window is not stalled

1 MS RLC transmit window is stalled

Table 6 SI bit

The Countdown Value (CV)field is sent by the mobile station to allow the network tocalculate the number of RLC data blocks remaining for the current uplink TBF. TheCV field is 4 bits in length and is encoded as a binary number with range 0 to 15.

The TLLI Indicator (TI)bit indicates the presence of an optional TLLI field within theRLC data block.





bit 1 TLLI indicator (TI) bit0 TLLI field is not present

1 TLLI field is present

Table 7 TLLI indicator bit

For EDGE the DL RLC/MAC header will change depends on the MCS used. TheMCS7, 8 and 9 have 5 octets header (header type 1) as shown on Table 8.

Bit8 7 6 5 4 3 2 1 Octet

TFI RRBP ES/P USF 1

BSN1 PR TFI 2

BSN1 3

BSN2 BSN1 4

CPS BSN2 5

Table 8 DL RLC/MAC header for EDGE MCS 7-9

Bit

8 7 6 5 4 3 2 1 OctetTFI RRBP ES/P USF 1

BSN1 PR TFI 2

BSN1 3

CPS BSN1 4

Table 9 DL RLC/MAC header for EDGE MCS 5 and 6 (header type 2)

Bit8 7 6 5 4 3 2 1 Octet

TFI RRBP ES/P USF 1

BSN1 PR TFI 2BSN1 3

SPB CPS BSN1 4

Table 10 DL RLC/MAC header for EDGE MCS 1 to 4 (header type 3)

There are three header formats, because the header code rates are different forMCS1-4 and MCS5-9, and MCS5-6 have one RLC/MAC block while MCS7-9 havetwo RLC/MAC blocks (see Table 13).

The Downlink RLC/MAC control block together with its MAC header is formatted asshown in Table 11.

Bit8 7 6 5 4 3 2 1

Payload Type RRBP S/P USF MAC header

RBSN RTI FS AC Octet 1 (optional)PR TFI D Octet 2 (optional)

Octet M

Control Message Contents...

Octet 21

Octet 22

Table 11 Downlink RLC/MAC control block together with its MAC header





The Uplink RLC/MAC control block together with its MAC header is formatted asshown in Table 12.

Bit8 7 6 5 4 3 2 1

Payload Type spare R MAC header

Octet 1

Octet 2Octet 3

Control Message Contents...

Octet 21

Octet 22

Table 12 Uplink RLC/MAC control block together with its MAC header

The detailed description of the different header formats can be found in 3GPP 04.60.

3.1.3 Logical Link Control

Logical Link Control (LLC) layer provides a reliable ciphered link between the SGSNand the MS. This protocol is independent of the underlying radio interface protocols.

LLC is considered to be a sub layer of layer 2 in the ISO 7-layer model. The purposeof LLC is to convey information between layer-3 entities in the MS and SGSN.Specifically, LLC shall support:

multiple MSs at the Um interface;

multiple layer-3 entities within an MS.

LLC includes functions for:

the provision of one or more logical link connections discriminated between bymeans of a DLCI;

sequence control, to maintain the sequential order of frames across a logicallink connection;

detection of transmission, format and operational errors on a logical linkconnection;

recovery from detected transmission, format, and operational errors;

notification of unrecoverable errors;

flow control

ciphering

LLC layer functions provide the means for information transfer via peer-to-peer logicallink connections between an MS and SGSN pair.

This layer can be operated in both acknowledged and unacknowledged modes, andthis is defined by the Quality of Service (QoS) profile within the PDP context (reliabilityclass).





3.1.4 SNDCP Layer

Maps the network level Packet Data Units (N-PDU) on to the underlying Logical LinkControl (LLC) layer. The basic functionality of SNDCP layer is listed below:

Multiplexer/demultiplexer for different network layer entities onto LLC layer

Compression of protocol control information (e.g. TCP/IP header)

Compression of data content (if used)

Segmentation/de-segmentation of data to/from LLC layer

In details the SNDCP shall perform the following functions:

Mapping of SN-DATA primitives onto LL-DATA primitives. Mapping of SN-UNITDATA primitives onto LL-UNITDATA primitives.

Multiplexing of N-PDUs from one or several network layer entities onto the

appropriate LLC connection. Establishment, re-establishment and release of acknowledged peer-to-peer

LLC operation.

Supplementing the LLC layer in maintaining data integrity for acknowledgedpeer-to-peer LLC operation by buffering and retransmission of N-PDUs.

Management of delivery sequence for each NSAPI, independently.

Compression of redundant protocol control information (e.g., TCP/IP header)at the transmitting entity and decompression at the receiving entity. Thecompression method is specific to the particular network layer or transportlayer protocols in use.

Compression of redundant user data at the transmitting entity anddecompression at the receiving entity. Data compression is performedindependently for each SAPI, and may be performed independently for each

PDP context. Compression parameters are negotiated between the MS andthe SGSN.

Segmentation and reassembly. The output of the compressor functions issegmented to the maximum length of LL-PDU. These procedures areindependent of the particular network layer protocol in use.

Negotiation of the XID parameters between peer SNDCP entities using XIDexchange.

3.1.5 IP, TCP/UDP and Application Layer

The IP (Internet Protocol), TCP/UDP (Transmission Control Protocol/ User DatagramProtocol) and application layers functionality is described in EDGE_TCP_TWEAK_1_2document in QP.

The Internet Protocol (IP)is a network-layer (Layer 3) protocol that containsaddressing information and some control information that enables packets to be routed.IP is documented in RFC 791 and is the primary network-layer protocol in the Internetprotocol suite. Along with the Transmission Control Protocol (TCP), IP represents theheart of the Internet protocols. IP has two primary responsibilities: providingconnectionless, best-effort delivery of datagrams through an internetwork; and providingfragmentation and reassembly of datagrams to support data links with differentmaximum-transmission unit (MTU) sizes.





Transmission Control Protocol (TCP)provides reliable transmission of data in an IPenvironment. TCP corresponds to the transport layer (Layer 4) of the OSI referencemodel. Among the services TCP provides are stream data transfer, reliability, efficientflow control, full-duplex operation, and multiplexing.

With stream data transfer,TCP delivers an unstructured stream of bytes identified bysequence numbers. This service benefits applications because they do not have tochop data into blocks before handing it off to TCP. Instead, TCP groups bytes intosegments and passes them to IP for delivery.

TCP offers reliability by providing connection-oriented, end-to-end reliable packetdelivery through an internetwork. It does this by sequencing bytes with a forwardingacknowledgment number that indicates to the destination the next byte the sourceexpects to receive. Bytes not acknowledged within a specified time period areretransmitted. The reliability mechanism of TCP allows devices to deal with lost,delayed, duplicate, or misread packets. A time-out mechanism allows devices to detectlost packets and request retransmission.

TCP offers efficient flow control, which means that, when sending acknowledgmentsback to the source, the receiving TCP process indicates the highest sequence numberit can receive without overflowing its internal buffers.

Full-duplex operation means that TCP processes can both send and receive at thesame time.

User Datagram Protocol (UDP) is a connectionless transport-layer protocol (Layer 4)that belongs to the Internet protocol family. UDP is basically an interface between IPand upper-layer processes. UDP protocol ports distinguish multiple applications runningon a single device from one another.

Unlike the TCP, UDP adds no reliability, flow-control, or error-recovery functions to IP.Because of UDP's simplicity, UDP headers contain fewer bytes and consume lessnetwork overhead than TCP.

UDP is useful in situations where the reliability mechanisms of TCP are not necessary,such as in cases where a higher-layer protocol might provide error and flow control.

UDP is the transport protocol for several well-known application-layer protocols,including Network File System (NFS), Simple Network Management Protocol (SNMP),Domain Name System (DNS), and Trivial File Transfer Protocol (TFTP).

The UDP packet format contains four fields; these include source and destination ports,length, and checksum fields.

Application-layer protocols are one piece of a network application. For example theWeb's application layer protocol is HTTP, and defines format and sequence ofmessages, application layer protocols for Push to Talk over Cellular (PoC) are RTP andSIP.

Application-layer protocol defines:

The types of messages exchanged, for example, request messages and responsemessages





The syntax of the various message types, such as the fields in the message andhow the fields are delineated

The semantics of the fields, that is, the meaning of the information in the fields

Rules for determining when and how a process sends messages and responds tomessages

3.2 RLC/MAC Coding Schemes

While the symbol rate is the same for GMSK and 8-PSK modulation the bit rate isdifferent since one GMSK symbol contains only 1 bit but one 8-PSK symbol contains3 bits altogether.

So the differentiations of RLC/MAC data rate of the different coding schemes arebased on convolutional coding and puncturing.

The CS1 and CS2 Coding Schemes (CS) are used for GPRS with PCU (PCU, PCU-S, PCU-T, PCU-B). If PCU2 (PCU2-U, PCU2-D) is implemented the CS3 and CS4 will

be used as well.

Modulation and Coding Schemes (MCS) are used for EGPRS both in GMSK and 8-PSK modulations.

3.2.1 GPRS Coding Schemes (CSs)

For error protection each RLC data block is encoded using one of the availablechannel coding schemes. ETSI has specified four coding schemes of which Nokiasupports coding scheme CS-1 and CS-2 only with PCU1, while PCU2 supports all thefour CSs (see the figure below).

Coding

Scheme

Payload (bits)

per RLC block

Data Rate

(kbit/s)

CS1 181 9.05

CS2 268 13.4

CS3 312 15.6

CS4 428 21.4

More Data=

Less Error

Correction

S11.5 with PCU2

Data

Error

C

PCU1

Coding

Scheme

Payload (bits)

per RLC block

Data Rate

(kbit/s)

CS1 181 9.05

CS2 268 13.4

CS3 312 15.6

CS4 428 21.4

More Data=

Less Error

Correction

S11.5 with PCU2

Data

Error

C

Data

Error

C

PCU1

Figure 15 Coding Schemes in GPRS

Each of the coding schemes has been developed based on a compromise betweenerror protection and the amount of user data carried. Coding scheme CS-1 has thelowest user data rate, but the highest error protection. CS-4 has the highest data ratebut no error protection on the user data.





The following figure shows the segmentation of an RLC block with MAC header incase of different CSs to/from the GSM TDMA frames.

CS-1

CS-2

CS-3

57 57 57 57 57 57 57 57

456 bits

MAC

USF BCS +4

puncturing

rate a/b convolutional coding

CS-1 CS-2 CS-3

RLC/MAC Block Size: 181 268 312

Block Check Sequence: 40 16 16

Precoded USF: 3 6 6

1/2 ~2/3 ~3/4

length: 456 588 676

0 132 220

Data rate (kbit/s): 9.05 13.4 15.6

interleaving

MAC

USF BCS

RLC/MAC Block Size: 428

BCS Size: 16

Precoded USF: 12

Data rate (kbit/s): 21.4

CS-4

20 ms

CS-1

CS-2

CS-3

57 57 57 57 57 57 57 57

456 bits

MAC

USF BCS +4

puncturing


CS-1 CS-2 CS-3



Precoded USF: 3 6 6

1/2 ~2/3 ~3/4

length: 456 588 676

0 132 220

Data rate (kbit/s): 9.05 13.4 15.6

interleaving

CS-1

CS-2

CS-3

57 57 57 57 57 57 57 57

456 bits

57 57 57 57 57 57 57 5757 575757 5757 57 575757 5757 57 575757 5757 57 575757 5757

456 bits

MAC

USF BCS +4

puncturing


CS-1 CS-2 CS-3



Precoded USF: 3 6 6

1/2 ~2/3 ~3/4

length: 456 588 676

0 132 220

Data rate (kbit/s): 9.05 13.4 15.6

interleaving

MAC

USF BCS


BCS Size: 16

Precoded USF: 12


CS-4

20 ms

MAC

USF BCS

MAC

USF BCS


BCS Size: 16

Precoded USF: 12


CS-4

20 ms20 ms

Figure 16 Coding Scheme segmentation in GPRS

The detailed segmentation procedure for CS1 and CS2 can be seen in the followingfigures.

USF Header & Data BCS

1/2 rate convolutional

coding + 4 tail bits

3 181 40 224 bits

6 456 bits

181bits/20ms = 9.05kbit/s



coding + 4 tail bits

3 181 40 224 bits

6 456 bits

181bits/20ms = 9.05kbit/s Figure 17 RLC/MAC segmentation for CS1







coding

6 268 16 294 bits

12588 bits

Puncturing (132 bits)

456 bits12

268 bits/20ms = 13.4kbit/s



coding

6 268 16 294 bits

12588 bits


456 bits12


Figure 18 RLC/MAC segmentation for CS2

When CS1-4 option is on, Dynamic Abis pool and (E)GPRS territories are createdand when a TBF is allocated to a TRX which supports EDAP then all GPRS codingschemes (CS1 CS4) are available for data transfer according to the parameterspcu_cs_hopping and pcu_cs_non_hop. If these parameters indicate Link Adaptation,the LA algorithm determines for each TBF separately which coding scheme (CS1 CS4) is used.

The detailed segmentation procedure for CS3 and CS4 can be seen in the followingfigures.



coding

6 312 16 338 bits

12676 bits


456 bits12




coding

6 312 16 338 bits

12676 bits


456 bits12








12 428 16

428bits/20ms = 21.4 kbit/s


12 428 16

428bits/20ms = 21.4 kbit/s


CS3 and CS4 is using modified LA algorithm (more details are available in Section7.6.2.

Coding schemes CS3 and CS4 are supported only by PCU2. It is application softwarefeature requiring a separate license.

To ensure successful BCSU switch-over it is not possible to enable CS3 & CS4 if

there are PCU1 units on the same slot as PCU2 in any of the BCSUs.

3.2.2 EGPRS Modulation and Coding Schemes (MCSs)

The EGPRS standard defines nine coding schemes MCS1 to MCS9, providingdifferent throughputs depending on the amount of redundancy implemented in eachcoding scheme.

In EGPRS MCSs the user data from higher layers and the RLC/MAC header arehaving different code rates. The header code rate is more robust for having theheader even in very bad radio conditions. That is why there are bad header, baddata and valid header, bad data counters.

The different data rates per timeslot are presented below:

Scheme Code rate HeaderCode rate

Modulation RLC blocksper Radio

Block(20ms)

Raw Datawithin one

Radio Block

Family BCS Tailpayload

HCS Data ratekb/s

MCS-9 1.0 0.36 2 2x592 A 59.2

MCS-8 0.92 0.36 2 2x544 A 54.4

MCS-7 0.76 0.36 2 2x448 B

2x12 2x6

44.8

MCS-6 0.49 1/3 1 592544+48

A 29.627.2

MCS-5 0.37 1/3

8PSK

1 448 B 22.4

MCS-4 1.0 0.53 1 352 C 17.6

MCS-3 0.80 0.53 1 296272+24

A 14.813.6

MCS-2 0.66 0.53 1 224 B 11.2

MCS-1 0.53 0.53

GMSK

1 176 C

12 6

8

8.8

NOTE: the italic captions indicate the padding.

Table 13 Coding scheme performance versus Eb/No.

The MCSs are divided into different families A, B and C. Each family has a differentbasic unit of payload: 37 (and 34), 28 and 22 octets respectively. Different code rates





within a family are achieved by transmitting a different number of payload units withinone Radio Block.

The family concept is used for retransmission only, so the retransmitted RLC/MACblocks MCS can be the initial MCS or an MCS inside the family.

For families A and B, 1 or 2 or 4 payload units are transmitted, for family C, only 1 or2 payload units are transmitted (see Figure 21 below).

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



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


Figure 21 MCS Families

The following figure shows the RLC/MAC segmentation (convolutional coding andpuncturing) to 4 normal GSM bursts.





P2 P3P1 P2

puncturingpuncturing

1836 bits

USF RLC/MACHdr.

36 bits

Rate 1/3 convolutional coding

135 bits

612 bits

612 bits124 bits36 bitsSB = 8

1392 bits

45 bits

Data = 592 bits BCS TB

612 bits

612 bits 612 bits

1836 bits

Rate 1/3 convolutional coding

EFBIData = 592 bits BCS TBEFBI

612 bits 612 bits 612 bits

P3 P1

3 bits

HCS

puncturing

Figure 22 MCS9 Coding and puncturing





4. (E)GPRS Procedures

The knowledge of (E)GPRS procedures can help to analyze the signaling traffic. Sobefore the analysis of signaling situation in Chapter 5 the procedure of

TBF establishment

Data transfer

TBF release

should be studied in details.

After GPRS Attach and PDP Context Activation the next procedure is the TBFestablishment with Packet Immediate Assignment (attach and PDP context activationalso require TBF establishment, but that is not discussed here in this section).

4.1 TBF Establishment

The TBF establishment is triggered by Channel Request (UL), Paging (DL) andImmediate Assignment (DL).

4.1.1 Channel Request and Packet Immediate Assignment

On receipt of a CHANNEL REQUEST message indicating a packet access, thenetwork may allocate a temporary flow identity and assign a packet uplink resourcecomprising one PDCH for an uplink temporary block flow in GPRS TBF mode.

On receipt of an EGPRS PACKET CHANNEL REQUEST message, the network mayallocate a temporary flow identity and assign a packet uplink resource comprising onePDCH for an uplink temporary block flow in EGPRS TBF mode or GPRS TBF mode.

(3GPP 04.18-8.0)

Channel Request Message: If the establishment cause in the CHANNEL REQUESTmessage indicates a request for a single block packet access, the network shall grantonly the single block period on the assigned packet uplink resource if the networkallocates resource for the mobile station.

EGPRS Packet Channel Request Message: If the establishment cause in the EGPRSPACKET CHANNEL REQUEST (EPCR) message indicates a request for a two phaseaccess, the network shall grant one or two radio blocks for the mobile station (within aMulti Block allocation) to send a PACKET RESOURCE REQUEST and possibly anADDITIONAL MS RADIO ACCESS CAPABILITIES messages on the assigned packetuplink resource if the network allocates resource for the mobile station.

Immediate Assignment Message: The packet uplink resource is assigned to themobile station in an IMMEDIATE ASSIGNMENT message sent in unacknowledgedmode on the same CCCH timeslot on which the network has received the CHANNELREQUEST or the EGPRS PACKET CHANNEL REQUEST message. There is nofurther restriction on what part of the downlink CCCH timeslot the IMMEDIATEASSIGNMENT message can be sent. Timer T3141 is started on the network side.





4.1.2 DL TBF Assignment

Reason for paging is DL user data or signaling while MS is on STANDBY state. Theterminal has to be paged by the network in the STANDBY state since its position isknown only on the Routing Area level.

5. Any LLC Frame

4. Any LLC Frame

3. GPRS Paging Request

2. Paging Request

1. PDP PDU

MS BSS SGSN

Figure 23 Paging flow chart

DL TBF Assignment, MS on CCCH

The DL TBF assignment is based on the following procedure (Figure 24).

TBF per priority90000(S10)

/c72084(S9)

packet_immed_ass_msg

/c72085(S9)

packet_immed_ass_ack_msg

MS BTS BSC SGSN

P-Immediate Assignment

Immediate Assignment (CCCH)P-Immediate Assignment Ack

Packet Polling Request

Packet Polling Request (PACCH)

Packet Control AckPacket Control Ack (PACCH)

MS on ready state

Sent on the PDTCH to findout the MS Timing Advance.In Nokia implementation,always sent when DL TBFAssignment is from CCCH.Not sent when DL TBF isassigned on PACCH

Packet Power Control/Timing Advance

Alternatively, Packet DownlinkAssignmnet may be sent if moretimeslots are required


DL TBF Establ.72005(S9)

DL RLC MAC/c72077(S9)

Max sim. DL TBF.72007(S9)


EGPRS DL TBF UNACK72091(S10)

EGPRS DL TBF72089(S10) PossiblyPossibly

Req 1tslDL72039(S9)

Alloc 1tslDL72049(S9)

Only 1 TCH isallocated first.

If requested andavailable


/c72084(S9)

packet_immed_ass_msg

/c72085(S9)

packet_immed_ass_ack_msg

MS BTS BSC SGSNMS BTS BSC SGSN

P-Immediate Assignment

Immediate Assignment (CCCH)P-Immediate Assignment Ack

Packet Polling Request

Packet Polling Request (PACCH)

Packet Control AckPacket Control Ack (PACCH)

MS on ready state

Sent on the PDTCH to findout the MS Timing Advance.In Nokia implementation,always sent when DL TBFAssignment is from CCCH.Not sent when DL TBF isassigned on PACCH


Alternatively, Packet DownlinkAssignmnet may be sent if moretimeslots are required


DL TBF Establ.72005(S9)





EGPRS DL TBF72089(S10) PossiblyPossibly

Req 1tslDL72039(S9)

Alloc 1tslDL72049(S9)

Only 1 TCH isallocated first.

If requested andavailable

Figure 24 DL TBF Assignment, MS on CCCH





DL TBF Assignment when UL TBF is ongoing

If there is an UL TBF ongoing, the channel request and immediate assignment is notneeded. The DL TBF is allocated by sending Packet Downlink Assignment onPACCH.

MS BTS BSC SGS

Packet Downlink Assignment (PACCH)

DL TBF DUR. UL/c72075(S9)


DL RLC Data Block

LLC PDU


Reqx ts lDL72039(S9)

Alloc x tsl DL72049(S9)

DL TBFEstabl.72005(S9)

DL RLC ACKMSC19/c79000(S10)

orDL RLC UNACK

MSC19/c79001(S10)



EGPRS DL TBF72089(S10)

New TBF is establishedin the same mode(GPRS, EGPRS) thanthe ongoing TBF.

If UL TBF isEGPRS

MS BTS BSC SGSMS BTS BSC SGS

Packet Downlink Assignment (PACCH)

DL TBF DUR. UL/c72075(S9)


DL RLC Data Block

LLC PDU


Reqx ts lDL72039(S9)

Alloc x tsl DL72049(S9)

DL TBFEstabl.72005(S9)

DL RLC ACKMSC19/c79000(S10)

orDL RLC UNACK

MSC19/c79001(S10)



EGPRS DL TBF72089(S10)

New TBF is establishedin the same mode(GPRS, EGPRS) thanthe ongoing TBF.

If UL TBF isEGPRS

Figure 25 DL TBF Assignment when UL TBF is ongoing





4.1.3 UL TBF Assignment

Depending on the network configuration different establishments procedures are usedduring the data connection. One phase access may reduce the TBF establishmenttime when accessing the cell and allows the system to allocate more than 1 RTSL for

the UL TBF.

When CCCH is in use, the Uplink Establishment offers:

GPRS: one-phase access is possible, but only 1 TSL can be allocated to theTBF. Timeslot reconfiguration would be needed for multi slot allocation

EGPRS: two-phase access is mandatory (in case of EPCR (S11, SX 4.0)implemented on CCCH the one phase access is possible as well)

When PCCCH is in use, the Uplink Establishment offers:

GPRS: one-phase access is possible. Network can allocate more than oneTSL to the UL TBF.

The gain is obtained from the transmission side due to timeslot allocation. InCCCH case only one TSL is assigned, while in PBCCH case there can bemore then one. This explains the increasing importance of the gain as theping packet size becomes bigger.

EGPRS: one-phase access is possible only if EGPRS Packet ChannelRequest (EPCR) is supported by the network (see Chapter 4.1.3.2). (If EPCRis not supported, then EGPRS is forced to use two-phase access even ifworking in the PCCCH.)

4.1.3.1 Channel Request - Packet Access Procedure (CCCH / PCCH)The following tables show the packet access procedure on CCCH (3GPP 04.18) and

PCCH (3GPP 04.60).

The table describes the differences of the Channel Request (S10.5ED)and EGPRSPacket Channel Request (S11) functionality. All the access modes are described inunacknowledged and acknowledged mode (8>= bit or 8< bit).





Purpose of the packetaccess procedure

EGPRS PACKET CHANNEL REQUESTsupported in the cell

EGPRS PACKET CHANNEL REQUESTnot supported in the cell

User data transfer requested RLC mode =unacknowledged

EGPRS PACKET CHANNEL REQUESTwith access type = 'Two-phase access'

CHANNEL REQUEST with establishmentcause = 'Single block packet access' forinitiation of a two-phase access

User data transfer requested RLC mode =acknowledged and numberof RLC data blocks ? 8(note 1)

EGPRS PACKET CHANNEL REQUESTwith access type = 'Short Access' or'One-phase access' or 'Two-phaseaccess'

63314619 E GPRS Radio Networks Planning Theory S13

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