(E)GPRS BASICS & KNOWLEDGE SHARING(E)GPRS BASICS & KNOWLEDGE SHARING

(E)GPRS OBJECTIVES

“2G Data EXPLAIN”

Main topics

• Basic GSM/GPRS/EDGE data network functionality

Concepts

• (E)GPRS = GPRS & EDGE

• EGPRS = EDGE

(E)GPRS - ContentFunctionality

• NE & interfaces

• Protocol stack

• TBF, Session Management, Mobility Management

Base Station Subsystem (BSS)

• Modulation (Air interface),

• EDAP and PCU (Resource allocation)

• Gb

SW and HW Releases

This material describes the Nokia (E)GPRS System with the following SW and HW releases:

• BSS SW:• BSS10.5, 11.0 and 11.5 and S12.0

• BSC variants with PCU1:• BSCi, BSC2, BSC2i, BSC3i

• BTS versions:• Talk, PrimeSite, MetroSite, UltraSite

• SGSN• SG5.0

CONTENT :- 1

Introduction

• Network Architecture and Interfaces

• Mobile Classes

• Network Protocols

• Multiframe and Header Structure

• Air Interface Mapping – Physical and Logical Channel

Procedures

• State and Mobility Management

• GPRS Attach/Detach

• Routing Area

• Session Management (PDP context)

• Temporary Block Flow

•RLC/MAC Header

•TBF Establishment

MSCHLR/AuCEIR

BSCBTSUm

PSTNNetwork

GSM & (E)GPRS Network Architecture

PCU

EDAPGb

Gateway GPRSSupport Node(GGSN)

Charging Gateway (CG) Local

AreaNetwork

Server

Router

Corporate 1

Server

Router

Corporate 2

Datanetwork(Internet)

Datanetwork(Internet)

Billing System

Inter-PLMNnetwork

GPRSINFRASTRUCTURE

BorderGateway (BG)

Lawful InterceptionGateway (LIG)

GPRSbackbo

nenetwork

(IP based)

Serving GPRSSupport Node(SGSN)

SS7Network

PAPU

(E)GPRS Network Elements and Primary Functions

SGSN• Mobility Management• Session Management• MS Authentication• Ciphering• Interaction with

VLR/HLR• Charging and

statistics• GTP tunnelling to

other GSNs

GGSN• Session

Management• GTP tunnelling to

other GSNs • Secure interfaces

to external networks

• Charging & statistics

• IP address management

Charging Gateway

• CDR consolidation

• Forwarding CDR information to billing center

Border Gateway• Interconnects

different GPRS operators' backbones

• Enables GPRS

roaming• Standard Nokia IP

router family

Domain Name Server• Translates IP host names to IP

addresses (DNS Resolution)• Makes IP network configuration

easier• In GPRS backbone SGSN uses

DNS to get GGSN and SGSN IP addresses (APN Resolution)

• Two DNS servers in the backbone to provide redundancy

Legal Interception Gateway• Enables authorities to intercept

subscriber data and signaling• Chasing criminal activity• Operator personnel has very

limited access to LI functionality• LI is required when launching the

GPRS service

GSM and (E)GPRS Interfaces

Gf

D

Gi

Gn

GbGc

CE

Gp

Gs

Signaling and Data Transfer InterfaceSignaling Interface

MSC/VLR

TE MT BSS TEPDN

R Um

GrA

HLR

Other PLMN

SGSN

GGSN

Gd

SM-SCSMS-GMSCSMS-IWMSC

GGSN

EIR

SGSN

Gn

(E)GPRS Interfaces

Gf

D

Gi

C

E

Gp

Gs

Signaling and Data Transfer InterfaceSignaling Interface

MSC/VLRTE BSS

TEPDN

R Um

Gr

HLR

Other PLMN

GGSN

Gd

SM-SCSMS-GMSCSMS-IWMSC

EIR

GnLAN

SW / IP BB

DNS CG LIG

Gn Ga

Gc

A

Gb

MT

SGSN SGSN GGSN

Gn

Gn Gn

Optional

GMSK & 8-PSK - Phase State Vectors

22,5° offset to avoid 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

Envelope (amplitude)

(0,0,1)

(1,0,1)

(d(3k),d(3k+1),d(3k+2))=

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

(0,1,1)

(1,1,1)

(1,1,0)

(1,0,0)

8-PSK Modulation

EDGE GSM + EDGE Modulation 8-PSK, 3bit/sym GMSK, 1 bit/sym Symbol rate 270.833 ksps 270.833 ksps Bits/burst 348 bits

2*3*58 114 bits 2*57

Gross rate/time slot 69.6 kbps 22.8 kbps

• 8-PSK (Phase Shift Keying) has been selected as the new modulation added in EGPRS

• 3 bits per symbol

• 22.5° offset to avoid origin crossing (called 3/8-8-PSK)

• Symbol rate and burst length identical to those of GMSK

• Non-constant envelope high requirements for linearity of the power amplifier

• Because of amplifier non-linearities, a 2-4 dB power decrease back-off (BO) is typically needed, Nokia guaranteed a BO of 2 DB for BTS

3/8

Phase states transitionsto avoid zero-crossing

GMSK and 8PSK BurstsdB

t

- 6

- 30

+ 4

8 µs 10 µs 10 µs 8 µs

(147 bits)

7056/13 (542.8) µs 10 µs

(*)

10 µs

- 1+ 1

(***)

(**)

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

GMSK Burst

8PSK Burst

Phase state vector diagram•Amplitude is not fixed•Origin is not crossed•Overshooting

8-PSK Modulation – Back-off Value

• Since the amplitude is changing in 8-PSK the transmitter non-linearities can be seen in the transmitted signal

• These non-linearities will cause e.g. errors in reception and bandwidth spreading.

• In practice it is not possible to transmit 8-PSK signal with the same power as in GMSK due to the signal must remain in the linear part of the power amplifier

Peak to Average of 3,2 dB

Pin

Pout

Back Off= 4 dB

Compression point

Peak to Average of 3,2 dB

Pin

Pout

Back Off= 4 dB

Compression point

• The back-off value is taken into account in link budget separately for UL / DL and bands: 900/850, 1800/1900)

• Too high MCA (8PSK) can lead to unsuccessful TBF establishment, if the MS is on cell border with low signal level (so the back-off is taken into account) and / or low C/I

Burst Structure

• Burst structure is similar with current GMSK burst, but term 'bit' is replaced by 'symbol'

• Training sequence has lower envelope variations

• Seamless switchover between timeslots

• In case of max output power only, back-off applied to 8-PSK

TSL1 TCH

GMSK

TSL2 TCH

GMSK

TSL3 TCH

GMSK

TSL4 TCH

GMSK

TSL5 PD T CH 8 - PSK / GMSK

TSL6 PD T CH 8 - PSK / GMSK

TSL7 PD T CH 8 - PSK / GMSK

TSL0 BCCH GMSK

P (dB)

t ( us )

EDGE Signal

1 2 3 4

1. Spectrum of Unfiltered 3pi/8 8psk modulation.

2. Filtered to fit GSM bandwidth.

3. Constellation after filtering: error vectors introduced.

4. Constellation after receiver Edge (equalised) filtering

GPRS Coding Schemes

• GPRS provides four coding schemes: CS-1, CS-2 and with PCU2 CS-3, CS-4

• PCU1 and 16 kbit/s Abis links support CS-1 and CS-2, the Dynamic Abis makes it possible to use CS-3 and CS-4

• Each TBF can use either a fixed coding scheme (CS-1 or CS-2), or Link Adaptation (LA) based on BLER

• Retransmitted RLC data blocks must be sent with the same coding as was used initially

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

Nokia GPRSPCU1

•CS1 & CS2 – Implemented in all Nokia BTS without HW change

•CS3 & CS4 – S11.5 (with PCU2) and UltraSite BTS SW CX4.1 CD1 (Talk is supporting CS1 and CS2)

Data

Err

or

Corr

ect

ion

GPRS Coding Schemes

Nokia GPRSPCU2

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

GPRS Coding Schemes

EGPRS Modulation and Coding Schemes

EGPRS modulation and coding schemes:

Scheme Modulation Data rate kb/s

MCS-9 59.2

MCS-8 54.4

MCS-7 44.8

MCS-6 29.6 27.2

MCS-5

8PSK

22.4

MCS-4 17.6

MCS-3 14.8 13.6

MCS-2 11.2

MCS-1

GMSK

8.8

Ref: TS 03.64

EGPRS Data Treatment Principle in RF Layer

User data

"Additional info" that does not require extra protection

Header part, robust coding for secure transmission

Adding redundancy

Puncturing of the coded info

BSC

BTS

• Class C Packet only (or manually switched between GPRS and speech modes)

• Class B Packet and Speech (not at same time) (Automatically switches between GPRS and speech modes)

• Class A Packet and Speech at the same time(DTM is subset of class A)

(E)GPRS Mobile Terminal Classes

(E)GPRS Multislot ClassesType 1

Multislot Classes 1-12- Max 4 DL or 4 UL TSL (not at same time)- Up to 5 TSL shared between UL and DL- Minimum 1 TSL for F Change- 2-4 TSL F Change used when idle

measurements required

Multislot Classes 19-29- Max 8 downlink or 8 uplink

(not required at same time)- 0-3 TSL F Change

Multislot Classes 30-45 (Rel-5)- Max 5 downlink or 5 uplink (6 shared)- Max 6 downlink or 6 uplink (7 shared)

Type 2

Multislot Classes 13-18- simultaneous receive & transmit- max 8 downlink and 8 uplink (Not available yet, difficult RF design)

DL

UL

DL

UL

1 TSL for F Change

1 TSL for Measurement

DL

UL

GPRS implementation

• GPRS/EGPRS capable terminals are required

• GPRS territory is required in BTS

• Packet Control Units (PCUs) need to be implemented in BSCs

• Gb interface dimensioning

• GPRS packet core network dimensioning

• If CS3&CS4 will be implemented following units/items are required• PCU2 with S11.5 BSC SW

• Dynamic Abis Pool (DAP)

• EDGE capable TRXs

• UltraSite and MetroSite BTS SW support

EGPRS Implementation

• Can be introduced incrementally to the network where the demand is

• EGPRS capable MS

• Network HW readiness/upgrade (BTS and TRX)

• TRS capacity upgrade (Abis and Gb!)

• Dynamic Abis

GMSK coverage

8-PSK coverage

AA-bis

Gb

Gn

BTS

BTS

BSC

SGSNGGSN

MSC

More capacity in interfaces to support higher data usage

EDGE capable TRX, GSM compatible

EDGE capable terminal, GSM compatible

EDGE functionality in the network elements

Create a BCF

Create a BTS

Attach BTS to RAC

Enable EGPRS (EGENA/Y)

Define GPRS and EGPRS parameters

Enable GPRS (GENA/Y)

Create a TRX with DAP connection

Create handover and power control parameters

The steps to create radio network objects

Enabling (E)GPRS

RAC= Routing Area code

Create the dynamic Abis pool

Disable the GPRS in the cell

Lock the TRX

Delete the TRX to be connected to Dynamic Abis pool

Create a TRX which uses the dynamic Abis pool

All the TRXs that will be using EGPRS in the BTS must be attached to a dynamic Abis pool

Unlock the TRX

Enable EGPRS in the BTS (EGENA/Y)

Enable GPRS in the cell (GENA/Y)

Unlock the BTS

Lock the BTS

The steps to enable the (E)GPRS in BSC

Enabling (E)GPRS

To be considered:• When the TRX has been created with EDAP defined at BSC and EGPRS feature is enabled,

the TRX must be attached to EDAP on the BTS side also not to fail the configuration of BCF

• EDAP in BSC must be inside the TSL boundaries defined in the BTS side• When modifying EDAP the size of EDAP in the BTS has to be the same as the size of EDAP in the

BSC

• Creating, modifying or deleting of EDAP in the BSC will cause a territory downgrade/upgrade procedure to all territories served by the PCU in question

• The ongoing EGPRS/GPRS connections will pause and resume immediately

• The maximum EDAP size is 12 timeslots

• EDAP must be located on the same ET-PCM line as TRX signaling and traffic channels

• There are no specific commissioning tests concerning EDAP

• EDAP must be located on the same BCSU as Gb interface

Enabling (E)GPRS

(E)GPRS Protocol Architecture

L1

L2

IP

UDP

GTP

USERPAYLOAD

GGSN

L1

L2

IP

GPRS Bearer

GGSN

Relay

IP

GPRS IP Backbone

L1

L2

IP

GTP

L1bis

NW sr

BSSGP

SNDCP

LLC UDP

SGSN

Relay

Gn

Internet

L1

L2

IP

TCP/UDP

APP

Gi

User information transferUser information transfer

LLC

SNDCP

IP

TCP/UDP

APP

RLC

MAC

GSM RF

MS

RLC

MAC

GSM RF

BSSGP

NW sr

L1bis

BSS

Ciphering and reliable link

Um Gb

Compression, segmentation

FIXED HOST

(E)GPRS Logical Channels

GPRS Air Interface Logical Channels

CCCHCommon Control Channels

DCHDedicated Channels

PCHPaging CH

AGCHAccess Grant CH

RACHRandom Access CH

Existing GSM Channels(Shared with GPRS Signaling in GPRS Release 1)

PACCHPacket Associated

Control CHPDTCH

Packet Data TCH

NEW GPRS Channels

Functionality - Content

Introduction

• Network architecture and Interfaces

• Mobile classes

• Network Protocols

• Multiframe and header structure

• Air interface mapping – physical and logical channel

Procedures

• State and Mobility Management

• GPRS Attach/Detach

• Routing Area

• Session Management (PDP context)

• Temporary Block Flow

•RLC/MAC Header

•TBF Establishment

(E)GPRS Procedures - Content

• Mobility Management and State Management• Mobile States

• GPRS attach

• GPRS detach

• Routing Area

• Session Management• PDP context activation

• Temporary Block Flow• RLC/MAC Header

• TBF establishment

GPRS Mobility Management - Mobile States

MS location not known, subscriber is not reachable by the GPRS nw.

IDLE READY

STANDBY

READY Timer expiry

MOBILE REACHABLE Timer expiry

Packet TX/RX

GPRS Attach/Detac

h

MS location known to Routing Area level. MS is capable to being paged for point-to-point data.

MS location known to cell level. MS is transmitting or has just been transmitting. MS is capable of receiving point-to-point data.

Attach Procedure

• The GPRS Attach procedure establishes a GMM context. This procedure is used for the following two purposes:

• a normal GPRS Attach, performed by the MS to attach the IMSI for GPRS services only

• a combined GPRS Attach, performed by the MS to attach the IMSI for GPRS and non-GPRS services

• Attach procedure description• MS initiates by sending Attach Request

• If network accepts Attach Request it sends Attach Accept• P-TMSI, RAI

• If network does not accept Attach request it sends Attach Rejected

• MS responds for Attach Accept message with Attach Complete (only if P-TMSI changes)

Detach Process

• GPRS Detach procedure is used for the following two purposes:• a normal GPRS Detach

• a combined GPRS Detach (GPRS/IMSI detach, MS originated)

• MS is detached either explicitly or implicitly:• Explicit detach: The network or the MS explicitly requests detach.

• Implicit detach: The network detaches the MS, without notifying the MS, a configuration-dependent time after the mobile reachable timer (MSRT) expired, or after an irrecoverable radio error causes disconnection of the logical link

Routing Area

The Routing Area Update procedure is used for the followings:

• a normal Routing Area Update

• a combined Routing Area Update

• a periodic Routing Area Update

• an IMSI Attach for non-GPRS services when the MS is IMSI-attached for GPRS services.

• Routing Area (RA)• Subset of one, and only one Location Area (LA)

• RA is served by only one SGSN

• For simplicity, the LA and RA can be the same

• Too big LA/RA increases the paging traffic, while too small LA/RA increases the signaling for LA/RA Update

Routing Area Location

Area (LA)

Routing Area (RA)

SGSN

MSC/VLR

GS Interface

• Bad LA/RA border design can significantly increase the TRXSIG on LA/RA border cells causing the cell-reselection outage to be longer

• LA/RA border should be moved from those areas where the normal CSW and PSW traffic is very high

•PDP Context (Packet Data Protocol): Network level information which is used to bind a mobile station (MS) to various PDP addresses and to unbind the mobile station from these addresses after use

•PDP Context Activation• Gets an IP address from the network• Initiated by the MS• Contains QoS and routing information enabling data transfer between MS and

GGSN• PDP Context Activation and Deactivation should occur within 2 seconds

Session Management - Establishing a PDP Context

PDP Context Request

155.131.33.55

MSC

PSTNNetwork

GPRSINFRASTRUCTURE

HLR/AuCEIR

Gateway GPRSSupport Node(GGSN)

Domain Name Server (DNS)

GPRSbackbo

nenetwork

(IP based)

PDP Context Activation - 11. MS sends "Activate PDP Context Request" to SGSN

2. SGSN checks against HLR

Datanetwork(Internet)

Datanetwork(Internet)

Access Point

SS7Network

APN= "Intranet.Ltd.com" 2.

Serving GPRSSupport Node(SGSN)

Access Point Name = Reference to an external packet data network the user wants to connect to

BSCBTSUm

1.

MSC

PSTNNetwork

GPRSINFRASTRUCTURE

HLR/AuCEIR

PDP Context Activation - 2Finding the GGSN

3. SGSN gets the GGSN IP address from DNS

4. SGSN sends "Create PDP Context Request" to GGSN

Datanetwork(Internet)

Datanetwork(Internet)

SS7Network

4.

Serving GPRSSupport Node(SGSN)

GPRSbackbo

nenetwork

(IP based)

3.

Domain Name Server (DNS)

Gateway GPRSSupport Node(GGSN)

Access Point

BSCBTSUm

DNS (Domain Name System) = mechanism to map logical names to IP addresses

MSC

GPRSINFRASTRUCTURE

HLR/AuCEIR

PSTNNetwork

PDP Context Activation - 3Access Point Selection

Access Point Name refers to the external network the subscriber wants to use

Datanetwork(Internet)

SS7Network

Serving GPRSSupport Node(SGSN)

GPRSbackbo

nenetwork

(IP based)

Domain Name Server (DNS)

Gateway GPRSSupport Node(GGSN)

Access Point

APN="Intranet.Ltd.com"

Datanetwork(Internet)

BSCBTSUm

MSC

PSTNNetwork

GPRSINFRASTRUCTURE

HLR/AuCEIR

Datanetwork(Internet)

Datanetwork(Internet)

Access Point

APN="Intranet.Ltd.com"

Domain Name Server (DNS)

SS7Network

5.

Serving GPRSSupport Node(SGSN)

GPRSbackbo

nenetwork

(IP based)

6.

Gateway GPRSSupport Node(GGSN)

BSCBTSUm

User (dynamic) IP address allocated

5. GGSN sends "Create PDP Context Response" back to SGSN

6. SGSN sends “Activate PDP Context Accept“ to the MS

PDP Context Activation - 4Context Activated

Temporary Block Flow

Temporary Block Flow (TBF):• Physical connection where multiple mobile stations can share one or more traffic

channels – each MS has own TFI• The traffic channel is dedicated to one mobile station at a time (one mobile station is

transmitting or receiving at a time)• Is a one-way session for packet data transfer between MS and BSC (PCU)• Uses either uplink or downlink but not both (except for associated signaling)• Can use one or more TSLs

Comparison with circuit-switched:• normally one connection uses both the uplink and the downlink timeslot(s) for traffic

In two-way data transfer:• uplink and downlink data are sent in separate TBFs - as below

BSBSCC

Uplink TBF (+ PACCH for downlink TBF)

Downlink TBF (+ PACCH for uplink TBF)

PACCH (Packet Associated Control Channel): Similar to GSM CSW SACCH

TLLI / TBF Concept

TBF (TFI + TSL)

MS SGSN GGSN

Internet or Intranet

GPRS CORE

BSS

TBF (RLC / MAC Flow)

TBF (LLC Flow)

PCUBTS

TLLI (SNDCP Flow)

P-TMSI

HLRVLR

IMSITMSI

Multiple Mobiles and Downlink Transmission

TFI2

TFI5

TFI3

TFI2

MSs

BTS

The TFI included in the Downlink RLC Block header indicates which Mobile will open the RLC Block associated with its TBF

RLC Data Block

• Several mobiles can share one timeslot

• Maximum of 7 Mobiles are queued in the Uplink

• Mobile transmissions controlled by USF (Uplink State Flag) sent on DL (dynamic allocation)

TS 1

TS 2

TS 3

Uplink State Flag

• Mobile with correct USF will transmit in following Uplink block

• Timeslot selected to give maximum throughput

New MS

Multiple Mobiles and Uplink Transmission

Multiple Mobiles and Uplink Transmission

USF = 1

USF = 2

USF = 3

USF = 3

MSs

BTS

RLC Data Block

The USF included in the Downlink RLC Block header identifies which Mobile will transmit in the following Uplink RLC Block

(E)GPRS Resource Allocation - Content

Territory method

• Default and dedicated territory

• Free TSLs

TSL Allocation

• Scheduling with priority based QoS

Territory Method

TRX 1

TRX 2

BCCH TS TS TS TS TS TSSDCCHBCCH TS TS TS TS TS TSSDCCHBCCH TS TS TS TS TS TSSDCCH

TS TS TSTS TSTS TS TSTS TSTS TS TS TSTS TS TSTS

TS

TS

= (E)GPRS Territory/Dedicated capacity

= CSW Territory

TS= (E)GPRS Territory/Additional capacity

BCCH= Signaling

TS = Free TSL for CSW

TS= (E)GPRS Territory/ Default capacity

Territory border

EDAP, PCU and Gb Functionality - Content

EDAP

• Abis vs. Dynamic Abis

• Channels carried on EDAP

• EDAP limits

• Abis PCM structure

PCU

• PCU procedures

• PCU types and limits

Gb

• Gb protocols

• Gb over FR

• Gb over IP

Abis Basic Concepts – PCM frame (E1)

One 64 kbit/s (8 bits) channel in PCM frame is called timeslot (TSL)One 16 kbit/s (2bits) channel timeslot is Sub-TSLPCM frame has 32 (E1) or 26 (T1) TSLs

One Radio timeslot corresponds one 16 kbit/s Sub-TSL (BCCH, TCH/F etc.) and one TRX takes two TSLs from Abis

0 MCB LCB123456789

101112131415161718 TCH 0 TCH 1 TCH 2 TCH 319 TCH 4 TCH 5 TCH 6 TCH 7202122232425 TRXsig2627 BCFsig28293031 Q1-management

One TRX has dedicated TRXsig of 16, 32 or 64 kbit/s.

48 kbit/s isnot allowed.

One BCF has dedicated BCFsig (16 or 64 kbit/s) for O&M

TRX1

Q1-management needed if TRS management under BSC

MCB/LCB required if loop topology is used

AbisBTS BSC

(E)GPRS Dynamic Abis Pool – EDAP Introduction• Fixed resources for signaling and

voice• Dynamic Abis pool (DAP) for data

• Predefined size 1-12 PCM TSL per DAP

• DAP can be shared by several TRXs in the same BCF (and same E1/T1)

• Max 20 TRXs per DAP• Max 480 DAPs per BSC• DAP + TRXsig + TCHs have to be

in same PCM• UL and DL EDAP use is

independent• DAP schedule rounds for each

active Radio Block• Different users/RTSLs can use

same EDAP Sub-TSL

0 MCB LCB1234 TCH 0 TCH 1 TCH 2 TCH 35 TCH 4 TCH 5 TCH 6 TCH 76 TCH 0 TCH 1 TCH 2 TCH 37 TCH 4 TCH 5 TCH 6 TCH 78 TCH 0 TCH 1 TCH 2 TCH 39 TCH 4 TCH 5 TCH 6 TCH 7

101112131415 EDAP EDAP EDAP EDAP16 EDAP EDAP EDAP EDAP17 EDAP EDAP EDAP EDAP18 EDAP EDAP EDAP EDAP19 EDAP EDAP EDAP EDAP20 EDAP EDAP EDAP EDAP21 EDAP EDAP EDAP EDAP22 EDAP EDAP EDAP EDAP232425 TRXsig1 TRXsig226 TRXsig327 BCFsig28293031 Q1-management

TRX1

TRX2

TRX3

EGPRS

pool

Nokia Dynamic Abis Dimensioning - with EGPRS Data Traffic

• Fixed master TSL in Abis for all EGPRS air TSL • Slave TSL’s (64 k) in EDAP pool for each air TSL• TRX and for OMU signaling fixed• TSL 0 and 31 typically used for signaling• EDAP pool dimensioning considerations

• Planned throughput in radio interface

RTSL territory size MS multiclass

• Number of TRXs/BTSs connected to DAP• Total number of PCU Abis Sub-TSLs • Gb link size• GPRS/EDGE traffic ratio

0 MCB LCB1 TCH 0 TCH 1 TCH 2 TCH 32 TCH 4 TCH 5 TCH 6 TCH 73 TCH 0 TCH 1 TCH 2 TCH 34 TCH 4 TCH 5 TCH 6 TCH 75 TCH 0 TCH 1 TCH 2 TCH 36 TCH 4 TCH 5 TCH 6 TCH 77 TCH 0 TCH 1 TCH 2 TCH 38 TCH 4 TCH 5 TCH 6 TCH 79 TCH 0 TCH 1 TCH 2 TCH 310 TCH 4 TCH 5 TCH 6 TCH 711 TCH 0 TCH 1 TCH 2 TCH 312 TCH 4 TCH 5 TCH 6 TCH 7

13 TRXsig 1 TRXsig 214 TRXsig 3 TRXsig 415 TRXsig 5 TRXsig 616 BCFsig171819 EDAP1 EDAP1 EDAP1 EDAP120 EDAP1 EDAP1 EDAP1 EDAP121 EDAP1 EDAP1 EDAP1 EDAP122 EDAP1 EDAP1 EDAP1 EDAP123 EDAP1 EDAP1 EDAP1 EDAP124 EDAP1 EDAP1 EDAP1 EDAP125 EDAP1 EDAP1 EDAP1 EDAP126 EDAP1 EDAP1 EDAP1 EDAP127 EDAP1 EDAP1 EDAP1 EDAP128 EDAP1 EDAP1 EDAP1 EDAP129 EDAP1 EDAP1 EDAP1 EDAP130 EDAP1 EDAP1 EDAP1 EDAP131 Q1-management

TRX 1

TRX 2

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TRX 5

TRX 6

EGPRS DAP

Packet Control Unit (PCU) - Introduction

• BSC plug-in unit that controls the (E)GPRS radio resources, receives and transmits TRAU frames to the BTSs and Frame Relay packets to the SGSN

• Implements both the Gb interface and RLC/MAC protocols in the BSS

• Acts as the key unit in the following procedures:• (E)GPRS radio resource allocation and management

• (E)GPRS radio connection establishment and management

• Data transfer

• Coding scheme selection

• PCU statistics

• The first generation PCUs are optimized to meet GPRS requirements, i.e. non real time solutions (QoS classes "Background" and "Interactive“)

• The second generation PCUs (PCU2) supports the real time traffic requirements and enhanced functionality (GERAN) beyond (E)GPRS

Gb Interface - Introduction

• The Gb interface is the interface between the BSS and the Serving GPRS Support Node (SGSN)

• Allows the exchange of signaling information and user data

• The following units can be found in Gb• Packet Control Unit (PCU) at the BSS side

• Packet Processing Unit (PAPU) at the GPRS IP backbone side

• Each PCU has its own separate Gb interface to the SGSN

BSC

PCU

BSS

SGSN

PAPU

GPRS

Gb

Gb Interface

• Allow many users to be multiplexed over the same physical resource

• Resources are given to a user upon activity (sending/receiving)

• GPRS signaling and user data are sent in the same transmission plane and no dedicated physical resources are required to be allocated for signaling purposes

• Access rates per user may vary without restriction from zero data to the maximum possible line rate (e.g., 1 984 kbit/s for the available bit rate of an E1 trunk)

BSC

PCU

BSS

SGSN

PAPU

GPRS

Gb

RF PLANNING VS DATA PERFORMANCE

CONTENTS

• FREQ. PLANNING

• C/I VS THROUGHPUT GRAPHS

Frequency Planning

Combined interference and noise estimations needed for (E)GPRS link budget

Frequency allocation and C/I level• The existing frequency allocation has high impact on EGPRS performance• Loose re-use patterns will provide better performance for all MCSs

Data rate and network capacity• EGPRS highest data rates require high C/I, typ > 20dB for MCS-7, 8 & 9• Possibly no extra spectrum for EDGE so efficient use of the existing spectrum is very

important• EGPRS traffic suited to BCCH use - typically the layer with highest C/I. But limited no. of TSLs

available on BCCH; may need to use TCH layer too

Sensitivity in tighter reuse and higher load• EDGE can utilize tighter reuse schemes and this is beneficial when planning for high load with

limited frequency resources• For systems with stringent spectrum constraints, EGPRS can offer good performance even

with tight re-use patterns (1/3 or 3/9). Load dependent

Data rate vs. CIR in Time (Field Measurement)

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Data ThroughputApplication Throughput

TEMS-C/I-GMSKPoly. (TEMS-C/I-GMSK)

Good quality environment

Data rate vs. CIR in Time (Field Measurement)

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TEMS-C/I-GMSKPoly. (TEMS-C/I-GMSK)

Average quality environment

Data rate vs. CIR in Time (Field Measurement)

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TEMS-C/I-GMSKPoly. (TEMS-C/I-GMSK)

Worse quality environment