Gprs Bss Operation

7/31/2019 Gprs Bss Operation

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BSC

RNC

MSCVLR

GMSC

CS

TRANSPORT NETWORK

ISDNPSTNPLMN

Gateway MSCMobile Services

Switching Center

Visitor LocationRegister

Base StationController

BaseTransceiverStation

Home LocationRegister

AuthenticationCentre

EquipmentIdentityRegister

Service ControlPoint

SGSN GGSN

Intermediate exchanges

B-Node Radio Network

Controller

Serving

GPRSSupportNode

IP BACKBONENETWORK

Routers

Internet

CorporateIntranet

Streaming

Services

Telemetry

Optional (specified). In practice

not implemented no mobileterminated data services

call routing and switchingcharging (CDR)database (subs. profiles)

securitymobility management

call routing and switching

charging (CDR)interface to external networksINCOMING CALLS

packet routing and switching

charging (CDR)database (subs. profiles)securitymobility management

session managementCIPHERING

compression (IP, payload) - /// features

packet routing and switchingcharging (CDR)

session managementinterface to external networksOUTGOING PACKETTRANSFERS

Gr GfGe

Gd

software hardware (PLD implemented)

HLR AUC EIR

SDP

GPRS

for prepaidSMSsymmetry line

Gb

Abis

IuIub

UTRANUMTS Terrestial

Radio Access Network

GERANGSM/EDGERadio Access Network

WPP: Wireless Packe Platform, AXE cabinetcompliant

J20: platform invented by JUNIPER (now ///)CPP: Connectivity Packet Platform

TSP: Telephony Server Platform (in futurereplacement of AXE)

RPP: Regional Processor with PCI bus

WPP/J20CPP

CPP

RBS AXE AXE

AXE

AXEPCURPP

PacketControlUnit

SCPAXE/TSP

UNIX

IN

Service Data Point

IntelligentNetwork

UNIXAXE AXE/UNIX

Gateway

GPRSSupportNode

~MSC

~GMSC

WPP

CH1. Introduction[OH] Fig.1-2. Page 12:GPRS logical architecture


2/38

Impact on RBS and A-bis

DXU 11

cTRU

cTRU

cTRU

cTRU

cTRU

cTRU

OLD RBS 2000

CS-1&2 new software

CS-3&4 new hardware

PCM

DXU 21

PCM

Local Bus

s

s

s

cTRU classical(old) CS 1&2

sTRU singleCS 1 - 4 + EDGE

DXU 21

dTRU

dTRU

dTRU

dTRU

dTRU

dTRU

NEW RBS 2000

PCM

NO Local Bus

dTRU doubleCS 1 - 4

dTRUe

CS 1 - 4 + EDGE

Y link

0 1 2 3 4 5 6 7

BSC/TRC

Um A-bis

0 1 2 3 4 30 31

GPRS

CS 1&2

speech

0 1 2 3 4

CS 1-4EDGE

5 30 31

SARAService Oriented Allocation of ResourcesOn A-bis InterfaceProblem with speech transmitted overTSs 4-7 wastage of resources on A-bis

[OH] Fig.1-3. Page 13: Structure of BSS and interfaces


3/38

[OH] Fig.1-3. Page 14: Gb Interface Physical Connections to the PCU

Packet Control Unit CH.2

PCU Description

Located in BSC. Only One PCU per BSC. Implemented in central software and regional hardware (RPP) with regional software. GPRS packet data radio resource management in BSS. Gb interface is terminated in PCU. Handles Medium Access Control (MAC) and Radio Link Control (RLC) layers of the radio interfaceand the BSSGP and Network Service layers of the Gb interface.

Regrional Processor with PCI Bus

A Power PC processor running at 333 MHz. 64 MB of SDRAM More than four times the CPU/memorycapacity of the RPG

Dual 10/100 Base TX Ethernet Two DL2 Group Switch interfaces Communicates via other RPPs via ethernet(duplicated)

May work towards Gb and Abis RPP#1or towards Abis only RPP#2

Cell may be controlled by one RPP only

[OH] Fig.2-2. Page 19: The PCU in the BSC

SGSN

GS

RPP#1

RPP#2

RPG

1 RPP ~ 4 RPG

SRS

Group Switch

Subrate Switch (used for CS1 & CS2)

EthernetGb

Abis

[OH] Fig.2-3. Page 20: PCU using frame relay with more than One RPP (CS-1 and CS-2)


4/38

PCU Hardware Description

RPPs are housed in Generic Device Magazines(GDM) Half-size

GS connection DL2 is distributed in the backplane byDigital Link Half-size Board (DLHB)

RP bus is distributed in the backplane by RP4 Ethernet is distributed in the backplane byEthernet Packet Switch Board (EPSB)

One RPP occupies 2 slots

Single GDM can house up to 7 RPPs

Function of DLHB

[OH] Fig.2-3. Page 22: RPPs in a GDM (BYB 501)

RP4

DLHB

RP4

DLHB

EPSB

Slot 0 1 2 3 4 5 6 7 8 15

EPSB

[OH] Fig.2-5. Page 23: Ethernet connectionbetween magazines

RPP#1

RPP#2

[OH] Fig.2-6. Page 24: GDM magazines equipped with RPPs (BYB501 hardware)

DLH

B

0123

45

14

15

DL 2 2Mb/s

16 physical connections in the backplane

DL3 34 Mb/s1 physical

connection

16 logical connections

GS


5/38

PCU Limitations

Maximum number of RPP: 64 book, now 128.

Maximum number of Cells: 512. Maximum number of PDCHs: 4096.

RPP Limitations

Maximum number of PDCHs: 150 software limitation (6 DSP*25 PDCHs) Maximum number of PDCHs: 64 hardware limitation for CS3&4, EDGE (64 Devices)

DSP#1

DSP#2

DSP#3

DSP#4

DSP#5

DSP#6

DSP#7

DSP#8

Can work only towards Gb

0 1 2

32 33 34

29 30 31

61 62 63

GS

RTGPHDV-0&&-31

RTGPHDV-32&&-63

1 RTGPHDV = 4 Logical PDCHs for CS1&2

1 RTGPHDV = 1 Logical PDCHs for CS3&4 and EDGE

0 1 2 3 4 5 6 7

Packet Data Channels (PDCHs)RADIO

LPDCH~PDCH

64 kb/s


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2 Different RPP configurations

RP working towards Gb and Abis

Max 150 PDCHs for CS 1&2 Max 45 PDCHs for CS 3&4 and EDGE

RP working towards Gb and Abis

Max 150 PDCHs for CS 1&2 Max 64 PDCHs for CS 3&4 and EDGE

DSP#1

DSP#2

DSP#3

DSP#4

DSP#5

DSP#6

DSP#7

DSP#8

0 1 2

32 33 34

29 30 31

61 62 63

SGSN

GS

18 19 20# of Gb Devices = 19 (max 32) GSL Devices

GSL Devices

DSP

#1

DSP

#2

DSP

#3

DSP

#4

DSP#5

DSP#6

DSP#7

DSP#8

0 1 2

32 33 34

29 30 31

61 62 63

SGSN

GS

GSL Devices

GSL Devices

Not used

[OH] Fig.2-8. Page 26: RPP Capacity


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GPRS Exchange Hardware (definition) CH.3

GS

RPP#1

RPP#2

TRAU

SRS

TRH MSC

SGSN

RPP#2

RPP#1

CS call

LLC frame

Segmentation

Compression

S

S

S

S

CS subscribersGPRS subscribersCS 1&2 are assumed

[OH] Fig.3-2. Page 31: BSC for 1500 TRXs

[OH] Fig.3-3. Page 32: GSM call and GPRS call


8/38

COMMAND DESCRIPTION

C change, I initiate, E end, B block.

Activation of GPRS Support in BSC

SYPAC: Command changes access for updating the values of AXE parameters

ACCESS=ENABLED, Access is enabled

PSW=XXXXXX; Access password must be given

DBTRI; Initiates database transaction

DBTSC: Changes data fields for an existing row in a tableTAB=AXEPARS, Specifies tableSETNAME=CME20BSCF, Specifies parameter setNAME=GPRS, VALUE=1;Specifies parameter, and value (1=active)NAME=GBCAPACITY, VALUE=2;Specifies Gb capacity (0-1023 in 64kb/s steps)

DBTRE: Commits database transactionCOM; Database is updated automatically

SYPAC:

ACCESS=DISABLED; Access is disabled

Enabling Ethernet in the PCU

Definition of RP Intercommunication Group (RPIG)

DBTRI;

DBTSI: Inserts a row in a tableTAB=RPSRPIGROUPS, Specifies tableGROUP=CHARLIE, Specifies name of intercommunication groupGROUPNO=1; Specifies number of intercommunication group

DBTRE: COM;


9/38

Enabling Ethernet in the PCU - concluded

Connection of RP to Ethernet Group

DBTRI;

DBTSI: TAB=RPSRPIRPS,

RPADDR=98, RP address

GROUP=CHARLIE; Group name

DBTRE: COM;

Deblocking of RP NET A and NET B in RPIG

BLRCE: Deblocking of RP communication netGROUP=CHARLIE,

NET=A; Net identifier (A or B)

Checking Ethernet status (working/not)

DBTSP: TAB=RPSRPISUPERVS,

GROUP=CHARLIE,

RPADDR1=98, Address for RP which is supervising the communicationRPADDR2=99, Address for the other RP in the supervisionNET=A; Intercommunication network

Checking which RPs have state UP

DBTSP: TAB=RPSRPISUPERVS,

GROUP=CHARLIE,

STATE=UP; Desired RP state (UP or DOWN)

Checking PCU configuration

RRPCP: Prints PCU Configuration DataRPINFO; Specific info about RPP state is included


10/38

Allocation of RP

1. Initiation of RPEXRPI:

RP=99, RP addressTYPE=RPPS1; RP type

2. Software loadingEXRUI:

RP=99,

SUID ="CXC 146 1002 R2A04"; Software Unit ID

3. Allocation of Extension Module

EXEMI:SUID="CXC1461002R2A04",

RP=99,

EQM=RTGPHDV-0&&-63, Equipment (devices for EM)

EM=2; EM address

4. Connection of Switching Network TerminalNTCOI: SNT=RTGPHDV-0, SNT name and number

SNTV=1, SNT version

SNTP=TSM-29-1; Switching Network Terminal Point

5. Connection of DevicesEXDUI: DEV=RTGPHDV-0&&-31; Device name and number

6. Deblocking of EMsBLEME: RP=99,

EM=0;

7. Deblocking of RPBLRPE: RP=99;

8. Deblocking of SNTNTBLE: SNT=RTGPHDV-0;

9. Taking devices into serviceEXDAI: DEV=RTGPHDV-0&&-31;

10. Deblocking of devicesBLODE: DEV=RTGPHDV-0&&-31;

GS

RPP

CP-B

CP-ARP bus

1

software 2

EM 0 EM 1 EM 2

3

SNTP

4

5

6 7 8 9 10

SNT


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Gb Interface CH.4

BSC

Base StationController

Base

Transceiver

Station

PCUPacket

ControlUnit

SGSN

Abis Gb

[OH] Fig.4-2. Page 45: Gb interface User Plane

Protocol Description user plane

SNDCPSubnetwork Dependent Convergence Protocol multiplexing of PDP Contexts (different IP/QoS) IP packet segmentation (segment length is dynamically controlled by the network; good radio longer segment) IP header compression IP payload compression

GGSNMS

SNDCP SNDCP

NSAPI 1 NSAPI 2

IP#1 IP#2 (max 5) APN #1 APN #2

NSAPI 1 NSAPI 2

GGSNMS

SNDCP SNDCP

NSAPI 2

QoS #1 QoS#2 Clip browsing Clip streaming

NSAPI 1 NSAPI 2

option, not implemented in all networks


12/38

Protocol Description user plane continued

LLCLogical Link Control sequence control (even if the cell has been changed)

error detection error correction by retransmission (acknowledgements between MS & SGSN) ciphering A5/3 GEA option, not implemented in all networks

MS identity TLLI (Temporary Logical Link Identifier) in 99,99% contains P-TMSI

RLCRadio Link Control positive/negative acknowledgement for the received data (acknowledgements between MS & BSC) retransmissions measurement reporting quality of the connection dynamic power regulation and Coding Scheme selection

MACMedium Access Control controls access to common resources (1 PDCH many users) TFI, USF allocation

BSSGP (BSS GPRS Protocol) transfer of LLC frames passed between an SGSN and an MS with radio related information negotiation of QoS profile (SGSN BSS) cell information for SGSN (BVCI) node management (flush) mobility management (paging)

NS (Network Service) provides communication paths between remote NS user entities load sharing between links (frame relay PVCs) link establishment detection if other links is down

[OH] Fig.4-3. Page 46: Gb interface Control Plane (signaling)


13/38

Gb interface definition

1. Network Service Entity Identifier NSEI

Uniquely identifies each BSC/PCU (as a collection of NSVCs) to the SGSN (and vice versa). PCU may be connected to one SGSN only. PCU can be connected to a SGSN via an intermediate transmission network (Frame Relay) or via point-to-point connection.

PCU can use one or more physical links to connect to a SGSN.

NSEI definition

RRNEI: Definition of NSEINSEI=1; NSEI unique in SGSN

2. Data Link Connection Identifier DLCI

Identifies local connection in Frame Relay network.

Defined between two FR nodes.

3. Network Service Virtual Connection Identifier NSVCI

Identifies virtual connection between SGSN and BSC/PCU.

DLCI and NSVCI definition

RRNSI: Definition of NSVCI and DLCINSVCI=1, NSVCI # unique in BSC/PCU

DLCI=100, DLCI # unique in BSC/PCU

DEV=RTGLT-2, First RTGLT deviceNUMDEV=5; Total # of consecutive RTGLT devices.

RRVBE: NSVCI=1; After the definition, the NSVCI must be deblocked

[OH] Fig. 4-4. Page 50: Frame Relay connection between the SGSN and PCUv

RPP

GS

ETC

SNT=ETRTG-0DEV=RTGLT-0&&-31

0 1 2 6 7 31

DEV=RTGLT-2

NUMDEV=5

0 1 2 4 31

allocated automaticallyby the system

DEV=RTGPHDV-0&&-31

[OH] Fig. 4-5. Page 51: NSEI definition

[OH] Fig. 4-7. Page 53: Effect of the RRNSI command


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4. BSSGP Virtual Connection Identifier BVCI

Identifies a virtual connection between the SGSN and a cell in BSS. Allocated immediately after activation of GPRS in the cell.

RLGSI: GPRS functionality activationCELL=C1AG11; Cell specification

Checking Gb status

RRGBP;

[OH] Fig. 4-6. Page 53: Gb interface commands

BSC

BSC

BSC

SGSN

PCU

FR switch

NSEI=1

NSEI=2

NSEI=3

1

1

1

DLCI=1062

NSVCI=13

DLCI=1002 DLCI=101

NSVCI=23

DLCI=1022NSVCI=33

DLCI=103DLCI=104

DLCI=1052P

CU

NSVCI=43

CELL 1

CELL 2

CELL 3

PCU

BVCI=1

BVCI=2

BVCI=3

4

4

4

SUMMARY


15/38

PCU Load Distribution

Procedure:

Selection of BVCs for redistribution. Selection of target RPP.

GS

RPP#1

RPP#2

Ethernet

RPP#3

BVCI

BVCI

BVCI

SGSN

Ethernet not working

GS

RPP#1

RPP#2

Ethernet

RPP#3

BVCISGSN

Ethernet working

Marked as blocked Marked as deblocked


16/38

GS

RPP#1

RPP#2

RPP#3

SGSN

After deblocking of RPP3 Calculated Number of BVCs per RP = 2

RP deblocking RP blocking/restart

BVCI

BVCI

BVCI

GS

RPP#1

RPP#2

RPP#3

SGSN

After blocking of RPP3 Calculated Number of BVCs per RP = 3

BVCI

BVCI

BVCI

GS

RPP#1

RPP#2

RPP#3

To which RPP allocate this cell?

Configuration of BVC (activation of GPRS in a cell)

BVCI

BVCI

NEW

BVCI

BVCI

GS

RPP#1

RPP#2

RPP#3

Move the cell to RP with sufficient GSL resources

Unsuccessful PDCH allocation due to GSL congestion (EDGE)

BVCI

BVCI

BVCI

No GSL dev for new PDCH


17/38

GEOGRAPHICAL STRUCTURE / NO POOL

MSC

MSCMSC

BSC

BSC

BSC

BSC

BSCBSC

Big City MSC

IDLE MODE ACTIVE MODE

LA UPDATEInter MSC HANDOVER

SGSN

SGSNSGSN

BSC

BSC

BSC

BSC

BSCBSC

Big City SGSN


RA UPDATEInter SGSN CELLCHANGE

- 1 9 -


18/38

GEOGRAPHICAL STRUCTURE / POOL

MSC

MSC

MSC

BSC

BSC

BSC

BSC

BSC BSC

Big City MSC


No LA UPDATE No Inter MSC HANDOVER

Big City SGSN


SGSN

SGSN

SGSN

BSC

BSC

BSC

BSC

BSC BSC

No RA UPDATENo Inter SGSNCELL CHANGE

- 2 0 -


19/38

GEOGRAPHICAL STRUCTURE

NO POOL POOL

SGSN

SGSN

SGSN

BSC

BSC

BSC

BSC

BSC BSC

SGSN

SGSN

BSC

BSC

BSC

BSC

Network utilization is geographicallydependent. Problem with dimensioning.

LONDON

SOHO

LONDON

BUSINESS

BSC

BSC SGSN

MSC failure/upgrage causes

loss of service area.

MSC

BSC

Addition of MSC requiresredesigning of radio network.

Easy dimensioning. Average trafficdistribution over the Whole geographical area.

MSC failure/upgrage only

causes problem with capacity.

To add MSC, data transcript fromexisting one may be used.

SGSN

- 2 1 -


20/38


21/38

Radio Interface CH.5

B,C D

D

Dedicated (Fixed)Packed Data Channels

On DemandPacket Data Channels

permanently reserved for GPRS

temporarily used by GPRS(dynamic allocation)

If no GSM traffic more PDCHs are allocated higher GPRS throughput.It is possible to specify priorities, e.g. GSM can preempt all GPRS channelson congestion or take only Idle ones.If On Demand PDCH becomes idle it is returned to CS domain afterPILTIMER( Packet Idle List Timer) expiry.

0 1 2 3 4 5 6 7

GSMBasic Physical Channels

TBF (Temporary Block Flow) transmission of data (radio blocks) over GPRS air interface signaling and traffic released if idle (classic approach)

release after 5 s (in practice) transmission over one or more TSs

TBF

5sTBF

TBF (new)

[OH] ------. ------: On Demand PDCH preemption


22/38

TBF is unidirectional (independent control of UL and DL radio resources) 1MS 1 UL () TBF 1MS 1 DL () TBF 1MS 1 UL () TBF + 1 DL () TBF

DL

UL

More than 1 MS per single PDCH

More than 1 PDCH per single MS (but only one TBF)

DL Transfer

TFI (Temporary Flow Identity) TBF ID (VALUES 0-31)

DL

TFI=3TS=3&4

TFI=1TS=4&5

TFI=7TS=6&7

TFI=1

OK (my TFI, process)DISCARD (not my TFI)

MSs listen to all PDCHs allocated to them. Moreover they readall radio blocks. However, only radio blocks allocated to them(proper TFI) are processed.Without QoS resources are divided evenly among all MSs.

(MSs and will use TS4 alternately.

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7


23/38

UL TransferUSF (Uplink State/Status Flag) (VALUES 0-7) transmitted downlink designates the MS that is allowed to transmit in UL direction on the particular TS

DL

UL

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

31USF

54TS

41USF

65TS

32USF

76TS

5USF

7TS

USF=1

1

2

USF=1

content addressed for

USF=4 USF=5

[Hint] Parameter TBF Granularity enables transmission of more UL Radio Blocks uponreception of proper TFI (TBF Granularity =4 4 Radio Blocks may be transmitted)


24/38

[OH] Fig. 5-2. Page 76: Logicalchannels in GSM

Logical Channels

GSM GPRSBCH:

FCCHSCHBCCH PBCCH

CCCH:PCH PPCHRACH PRACHAGCH PAGCH

DCH:SDCCHFACCH PACCH

SACCH

PTCCH

TCH PDTCH

Option which requires Master PDCH. (GPRSNWMODEparameter)MPDCH - first of dedicated PDCH, carry DATA + SIGNALING

(80-90%) (10-20%)

B,C D

D

M

0 1 2 3 4 5 6 7

Basic Physical Channel may carrydifferent types of information

[OH] Fig. 5-3. Page 76: Logicalchannels in GPRS

[OH] ------. ------: Cell without MPDCH

[OH] ------. ------: Cell with MPDCH

Presence of MPDCH depends on Network Operation Mode


25/38

NETWORK OPERATION MODES

BSC

MSC

SGSN

Gs

ACTIVE DATATRANSFER

CS PAGING MULTIPLEXEDWITH USER DATA

PCH

MS LISTENS

ONLY TO PCHCS PAGINGPS PAGING

-COMBINED RA&LA UPDATE

-COMBINED GPRS/IMSI ATTACH-PAGING COORDINATION

NOM I no MPDCH

BSC

MSC

SGSN

Gs

ACTIVE DATATRANSFER

CS PAGING MULTIPLEXED

WITH USER DATA

PPCH

MS LISTENSONLY TO PPCH

NOM I, MPDCH exists

PCHPCH FOR NON GPRS MSs

BSC

MSC

SGSNPCH

MS LISTENS

ONLY TO PCH

-NO PAGING COORDINATION WITH DATA TRANSFER

NOM II (no MPDCH)

NO Gs

BSC

MSC

SGSN

PPCH

MS LISTENS TO PCH

AND PPCH

-NO PAGING COORDINATION WITH DATA TRANSFER

NOM III (MPDCH exists)

NO Gs

PCH

parameter GPRSNWMODE=0

GPRSNWMODE=1

GPRSNWMODE=2

GPRSNWMODE=3


26/38

DUAL TRANSFER MODE

MS Classes

A

B

C

DTM (simplified A)

0 1 2 3 4 5 6 7

GSM and GPRS channel allocation must be coordinated.(GPRS channel administration is responsible for this).

PAGING

BSC is responsible for paging coordination.

BSC

MSC

SGSN

NO Gs

DATA TRANSFER

CS PAGING

PS PAGING

FACCH

RA/LA UPDATE

BSC is responsible for RA/LA update coordination.

MS must support DTM. However, paging coordination

works for all MSs (session must be suspended)

BSC

MSC

SGSN

LA UPDATESDCCH

RA UPDATETUNNELED


27/38

Allocation of FPDCH

RLGSC: Changing of GPRS cell parameters

CELL=KISTA, Cell name

FPDCH/SPDCH=3, Number of Fixed/Semi-dedicated PDCHs (max 16)MPDCH=YES/NO; Allocation of MPDCH in the cell

RLCLC: CELL=KISTA, CSPSNOPRF No selection preference.CSPSALLOC= CSNOPRFPSFIRST No selection preference for CS and select TCHs first for PS.

CSNOPRFPSLAST No selection preference for CS and select TCHs last for PS.

Setting the Network Operation Mode

RAEPC: Changing exchange properties (many different properties are changed with this command)

PROP=GPRSNWMODE1; Choosing appropriate NOM

Coding Schemes

Selection of default coding scheme for the whole BSC/PCU

RAEPC:

PROP=CHCODING1; Choosing appropriate channel coding 1 CS1 , 2 CS2 (UL,DL)

Selection of dedicated coding scheme for the particular cell

RLGSC: CELL=KISTA, Cell name

NA

CS1

CHCSDL= CS2, CS downlink for the particular cell. If NA is selected, the exchange property CHCODINGCS3 is usedCS4

LA =ON/OFF; Activation of Link Adaptation feature. CS specified by CHCSDL will be taken as initial value.

[OH] Fig. 5-15. Page 87: Coding schemes

[OH] ------. ------: 1 & 2 & 3 & 4


28/38

Definition of required number of PDCH

RLBDC: Changing configuration of BPDCH

CELL=KISTA, Cell name

CHGR=0-15, Channel Group number

NUMREQBPC=8-128, Number of required BPCs, if not given all TSs are GPRS capable

NUMREQCS3CS4BPC=0-128 Number of required GPRS CS-3 or CS-4 BPCs

NUMREQEGPRSBPC=0-128, Number of required EGPRS BPCs

TN7BCCH=GPRS/EGPRS; This parameter indicates if Timeslot Number (TN) 7 on the BCCHfrequency can be configured with Traffic Channels (TCHs)supporting EGPRS or GPRS only.

Activation of Dual Transfer Mode in the cell

RLDUI: Changing configuration of BPDCHCELL=KISTA, Cell name


29/38

GSM GPRS

RBS

C/I

distance

50%/50%

Too much coding

50%/50%

Not enough coding Coding is dynamically changed

distance

CS4 20K CS3 14.4K CS2 12K CS1 8K

BSCRBS

13 kb/s user data

MS

TCH 22.8 kb/s

Channel Coding

C/I

ThroughputCS4

CS3

CS2

CS1


30/38

Selection of Max # of TBFs UL and DL

RAEPC:PROP=TBFDLLIMIT2; Desired max # of DL TBFs sharing one PDCH.

Value range is 1 8PROP=TBFULLIMIT2; Desired max # of UL TBFs sharing one PDCH. Value

range is 1 6PROP=PILTIMER20; PILTIMERvalue. Protection of PDCHs from returning

to CS domain

Specification which on-demand PDCHs that are possible to pre-empt to be used forcircuit switched calls.

RLGSC:

CELL=KISTA,

0 All on-demand PDCHs are possible to preempt1 On-demand PDCHs not used for Dual Transfer Mode (DTM)

are possible to preempt2 On-demand PDCHs not used for Streaming are possible to preempt

3 On-demand PDCHs not used for DTM nor for Streaming are possiblePDCHPREEMPT= 4;On-demand PDCHs that are not essential are possible to preempt

5 On-demand PDCHs that are not essential nor DTM PDCHs are 6 On-demand PDCHs that are not essential nor Streaming PDCHs 7 On-demand PDCHs that are not essential nor DTM nor Streaming 8 Idle on-demand PDCHs are possible to preempt

[OH] -----. -----: Channel reservation strategy


31/38

MSC/VLR service area SGSN service area

LA#1 LA#2

LA#3

LA Location Area RA Routing Area

Locationupdate

RA#1 RA#2

RA#4

RA#3RA#5

Routing Area

update

Paging inside RA/LA

RA LA in /// RA=LARA cannot be divided between many LAs

[OH] Fig. 5-17. Page 90: Location Area (LA) and Routing Area (RA)

CGI containing Location Area Codeis defined with RLDECcommand


32/38

[OH] Tab. 6-1. Page 100: GPRS and EDGE: EDGE/GPRS technical data.

[OH] Fig. 6-3. Page 102: EDGE Introduces New Modulation

1/The same bit 3,7 s

0/Different bit

0,0,0

0,0,1

0,1,0

0,1,1

1,1,1

1,0,1 1,1,0

Q

I

1,0,0

amplitude (const.)

phase

1

2

3011 110 000

1 2 3

amplitude (var.)

Problem amplitude = 0Solution axis rotate

Q

I

SS

time

SS

time

[Q] Why transmission power in EDGE is lower, comparing with GMSK ?

GMSK

GaussianMinimumShiftKeyiing

8-PSK

8 - PhaseShiftKeyiing

Class C amplifier required.

Simple and cheap

Class A amplifier required.

Expensive and complicated

PPEAK GMSK = PPEAK EDGE

PAV GMSK > PAV EDGE~3dB

MS measures average power.

EDGE Solution Description CH.6


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Different power causes problem with stability at the cell border.

EGPRS 8PSK GPRS GMSK

Cell border changes depending on

transmission method.

Unstable region

Solution no 8PSK on BCCH carrier or no 8PSK on TS 0 & 7 of BCCH carrier

GMSK vs 8PSK

TX RX

interferenceinterference

TX RX

Lower bitrate. High bitrate. Lower resistance to interferences (symbols are

High resistance to interferences thanks to large distances close). Solution good radio, dynamic adaptation of codingbetween symbols. and modulation (back to GMSK)

large distancesmall distance

[OH] Fig 6 5 Page 105: Coding Schemes for GPRS and EDGE (standard improvement)


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[OH] Fig. 6-5. Page 105: Coding Schemes for GPRS and EDGE (standard improvement)

GPRS

EGPRS

Coverage Area for GPRS bitrate achieved from 1 TS is at least 8 kb/s

8PSK

[Q] What is coverage area for GPRS ?

GMSK

Coding SchemeModulation Mobile Coding SchemeMCS

[Q] Why coverage for EGPRS with GMSK is greater than GPRS with GMSK ?

~3dB Processing Gain.Result of better coding schemes and more efficient protocols.

Improvements in EDGE


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Improvements in EDGE

[OH] Fig. 6-6. Page 106: Retransmission in EGDE in comparison to GPRS

#1 sequential number

#2

#3

coding user data

#2

In GPRS retransmission is allowed onlywith the same coding scheme.

#???

GPRS protocols do not allow splittingone block into smaller parts due toproblems with numbering. No spaceIn protocol header for 2.1 & 2.2.

Transmission window 64 frames(stall if exceeded)

#2 retransmission, more coding required

#1 ACK, #3 ACK, #2 NOT ACK

CS 4

CS 2

#1

NOT ACK

#1

In EDGE retransmission is allowed withdifferent coding scheme and modulation.

#2

MCS 9

MCS3(GMSK)

#2

MCS 6

NOT ACK

NOT ACK

#1.1

#1.2

#2.1

#2.2

[OH] Tab. 6-2. Page 106: Coding schemes (Link Adaptation)

Transmission window 1024 frames


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[OH] HANDOUT: Incremental Redundancy

[OH] HANDOUT: MCS-9 and MCS-5 - comparison

INCREMENTAL REDUNDANCY enables utilization of less robust codec (MCS 9) in radio conditions suitablefor more robust codec (MCS 5)

[Q] Why to introduce Incremental Redundancy ?

C/I

Radio conditions are changing constantly. In some cases only one or two transmissions are sufficient for properdecoding of the transmitted signal with incremental redundancy. Throughput is increased.

Incremental redundancy requires MS buffer for soft combining. If buffer is exceeded link adaptation is utilized.

1transmission

2 transmissions

3 transmissions

[Hint] In GPRS 10% of the whole transmitted data are retransmissions (for good network)

In EDGE 40% of the whole transmitted data are retransmissions (for good network)

Selection of Default Modulation and Coding Scheme (MCS) DL/UL


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Selection of Default Modulation and Coding Scheme (MCS) DL/UL

RAEPC: Changing exchange properties

PROP=LQCDEFAULTMCSDL5; Default MCS downlink. Values 1-9 ~ MCS1-MCS9 (valid if LQCACT1 or 3, no EGPRS LinkQuality Control DL)

PROP=LQCDEFAULTMCSUL5; Default MCS upnlink. Values 1-9 ~ MCS1- MCS9(valid if LQCACT2 or 3, no EGPRS Link QualityControl UL)

Activation/Deactivation of EGPRS Link Quality Control (ELQC)

RAEPC: 0 ELQC deactivatedPROP=LQCACT 1; ELQC activated for DL TBFs only

2 ELQC activated for UL TBFs only3 ELQC activated for DL and UL TBFs

Limiting the highest MCS than can be selected by the system in LQC procedures (UL/DL)

RAEPC: PROP=LQCHIGHMCS9; Values 1-9 ~ MCS1- MCS9

Link Adaptation and Incremental Redundancy (LA/IR/BLER) activation

RAEPC:

0 LA modePROP=LQCMODEDL/UL 1;

LA/IR mode2 LA/IR BLER mode

T ffi Fl D i ti CH 7


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Traffic Flow Description CH.7

[OH] Fig. 7-2. Page 113: Call to a CS mobile

[OH] Fig. 7-5. Page 117: GPRS transaction (CS-1 and CS-2) with On-demand or Fixed PDCH

[OH] Fig. 7-6. Page 117: EDGE or GPRS transaction (CS-3 and CS-4) with Ondemand or Fixed PDCH

[OH] Fig. 7-7. Page 118: GPRS transaction with Master PDCH

BSC Exchange Properties for GPRS and EGPRS

CH.8

Discussed during previous chapters

OSS RC for GPRS CH.9[OH] Fig. 9-2. Page 145 --- Fig. 9-11. Page 159

Gprs Bss Operation

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