GPRS Telecom Presentation

GPRS telecom presentationED 02 released

MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 1/2

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

SiteVELIZY MOBILE COMMUNICATION DIVISION

Originator(s)

Jardel JP

GPRS telecompresentation

Domain : Alcatel 900/BSSDivision : Product DefinitionRubric : SYS-TLAType : System Functional BlocksDistribution Codes Internal : External :

PREDISTRIBUTION:

MCD/TD Vélizy: L. Cruchant PJ Pietri D. IsidoroJY Amaudrut M. Wu JP HumeauS. Baudet JC Barthelemy F. Huet

R Bialobroda R Le HegaratC. Charmont G. Linden

S. Bourdeaut B. De-Jaeger S. PegaE. Desorbay M. Delprat C. RamondP. Dupuy T. DonzelB. Landais J. Guinand

MCD/TD Kontich: BDC doc managerMCD/TD Kaisemer: BTS-HW doc managerMCD/TD Zuffenhausen: NMA doc managerMCD/TD Berlin:

PREDISTRIBUTION: DOC. CENTRES

MCD VELIZY MCD STUTTGART MCD ANTWERPB. Marliac I. Lentzsch L. Van Eyck

ABSTRACT

This document is a presentation of GPRS telecom layers, in B6.2.

Approvals

Name

App.

D.BerthoumieuxSM

R. GödeckerBTS SSAM

R. BialobrodaMFS SSAM

Name

App.

L. DierickBSC SSAM


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 2/2

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

REVIEW

Ed. 01 Proposal 02 21-12-98 TD/SYT/JPJ/81243/Ed.1Ed 02 Proposal 01 30-09-99 TD/SYT/JPJ/90531/Ed.1

HISTORYEd. 01 Proposal 01 06-07-98 first draftEd. 01 ip02 21-08-98 - remarks of last working meeting

- O&M interfaces have been detailed- RRM and BSCGP specification evolutions, taken intoaccount- NS-VC management function description

Ed. 01 released 02-02-99 document updated according to review remarks(TD/SYT/JPJ/81243/Ed.1)

Ed. 02 Proposal 01 10-06-99 miscellaneous updatesEd. 02 released 30-09-99

INTERNAL REFERENCED DOCUMENTS

Not applicable

FOR INTERNAL USE ONLY

Not applicableEND OF DOCUMENT


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 1/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel TABLE OF CONTENTS

HISTORY ......................................................................................................................................... 2

REFERENCED DOCUMENTS ......................................................................................................... 2

RELATED DOCUMENTS............................................................................................................... .. 2

PREFACE ........................................................................................................................................ 2

1. SCOPE 6

2. GENERAL INTRODUCTION TO GPRS 7

2.1 Introduction 7

2.2 General architecture 8

2.3 GPRS interfaces 9

2.4 Protocol layers 102.4.1 Transmission plane 102.4.2 Signalling plane 11

3. GPRS NETWORK OPERATION 12

3.1 Definitions 123.1.1 GPRS Mobile station classes 123.1.2 IMSI (International Mobile Subscriber Identity) 123.1.3 P-TMSI (Packet Temporary Mobile Subscriber Identity) 123.1.4 TLLI (Temporary Logical Link Identity) 123.1.5 Location Area Identity (LAI) 123.1.6 Routeing Area Identity (RAI) 13

3.2 Session management 133.2.1 Attach/Detach procedures 133.2.2 PDP context 14

3.3 Mobility Management 153.3.1 MM states 153.3.2 Location Management Function 15

3.4 Interactions between SGSN and MSC/VLR 163.4.1 Paging coordination 163.4.2 Paging for GPRS downlink transfer 193.4.3 Paging for CS connection establishment 19

4. ALCATEL ARCHITECTURE 20

4.1 BSS architecture 204.1.1 PCU Concept 20


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 2/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

4.1.2 ALCATEL implementation 224.1.3 Transmission plane 234.1.4 Control plane 244.1.5 Physical interfaces 26

4.2 GPRS global architecture 31

5. GPRS RADIO INTERFACE 32

5.1 Interfaces description 32

5.2 Um interface 335.2.1 GSM-RF layer 335.2.2 packet data logical channels 345.2.3 Channel coding 385.2.4 Cell re-selection 395.2.5 Timing advance 395.2.6 Power control 425.2.7 Discontinuous reception (DRX) 435.2.8 System information broadcasting 44

5.3 BSCGP layer 455.3.1 BSCGP layer functions 455.3.2 Radio resource management 46

5.4 GCH layer 48

5.5 RRM/RLC/MAC Layers 495.5.1 Definitions 495.5.2 RRM functions 525.5.3 RLC functions 645.5.4 MAC functions 65

6. GB INTERFACE 68

6.1 Protocol layers 686.1.1 Link layer 686.1.2 Network Service layer 686.1.3 BSSGP layer 69

6.2 Addressing 696.2.1 Permanent Virtual Channel (PVC) 696.2.2 Bearer Channel (BC) 696.2.3 Network Service Virtual Connection (NS-VC) 696.2.4 Network Service Entity (NSE) 706.2.5 BSSGP Virtual Connection (BVC) 70

6.3 NS functionalities 736.3.1 Load sharing function 736.3.2 NS-VC management function 76

6.4 BSS GPRS Protocol (BSSGP) functionalities 786.4.1 Data transfer procedures between RL and BSSGP SAPs 796.4.2 Signalling procedures between GMMSAPs 806.4.3 Signalling procedures between NMSAPs 81


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 3/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

7. O&M INTERFACE 84

7.1 Interface modelisation 84

7.2 Managed entities, in the MFS 857.2.1 GSL entity 877.2.2 BSS entity 887.2.3 Gic group entity 897.2.4 Cell entity 907.2.5 BVC-PTP entity 917.2.6 BVC-SIG entity 927.2.7 NSVC entity 937.2.8 PVC entity 947.2.9 BC entity 95

7.3 Telecom layer initilisation 96

7.4 Performance management 967.4.1 Counters creation 977.4.2 Counters deletion 987.4.3 Counter periodical retrieval 987.4.4 Threshold handling 987.4.5 Tide-mark handling 98

8. GPRS SCENARIOS 99

8.1 Paging for downlink packet transfer 998.1.1 PCCCH utilization 1008.1.2 CCCH utilization 101

8.2 Packet data transfer 1028.2.1 Definitions 1028.2.2 Packet data downlink transfer 1038.2.3 Packet data uplink transfer 112

8.3 Autonomous cell reselection 119

8.4 Cell reselection during an UL transfer 120

8.5 Cell reselection during a DL transfer 121

9. TELECOM FUNCTIONAL BLOCKS 122

10. GLOSSARY 123


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 4/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

02 30-09-99 MCD/TD MCD/TD/SYT01 02-02-99 MCD/TD MCD/TD/SYTED DATE CHANGE NOTE APPRAISAL AUTHORITY ORIGINATOR


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 5/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

HISTORY

Ed. 01 released 02-02-99 document updated according to review remarks(TD/SYT/JPJ/81243/Ed.1)

Ed. 02 released 30-09-99 miscellaneous updates

REFERENCED DOCUMENTS

[1] GSM 03.60 GPRS service description[2] GSM 03.64 GPRS overall description of the GPRS radio interface[3] GSM 04.60 GPRS MS-BSS interface, RLC/MAC protocol[4] GSM 08.16 GPRS BSS-SGSN interface, Network Service[5] GSM 08.18 GPRS BSS-SGSN interface, BSSGP protocol

RELATED DOCUMENTS

[6] 3BK 11202 0257 GPRS Gb interface - BSSGP layer[7] 3BK 11202 0258 GPRS Gb interfcae - Network Service Control Sub-layer[8] 3BK 11202 0259 GPRS Gb interface - Sub-Network Service Sub-layer[9] 3BK 11202 0260 GPRS MFS-BSC interface - BSCGP layer

[10] 3BK 11202 0261 GPRS MFS-BSC interface - GSL stack[11] 3BK 11202 0262 GPRS MFS-BTS interface - GCH stack[12] 3BK 11202 0263 GPRS radio interface - MAC sub-layer[13] 3BK 11202 0264 GPRS radio interface - RLC sub-layer[14] 3BK 11202 0265 GPRS radio interface - RRM sub-layer[15] 3BK 11202 0266 GPRS radio interface - physical link layer[16] 3BK 11203 0039 Transmission functional specification[17] 3BK 11200 0017 Transmission Architecture[18] TD/SAS/OBE/80685.98 MFS/GPU Dimensioning[19] 3BK 10204 0433 TFD Multi-BSS Fast packet Server[20] 3BK 10204 0438 TFD General Packet Radio Service

PREFACE


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 6/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

1. SCOPE

This document is a presentation of GPRS telecom layers, in B6.2.The aim of this document is to introduce telecom layer specifications ([6] to [15]), to give to thereader a general overview.Therefore, protocols which are described in this document do not deal with all the cases.Furthermore, in the case of am biguities between this document and a specific l ayerspecification, the specific l ayer specification takes precedence .

This document is structured in the following way:- chapter 2 is an introduction to GPRS.- chapter 3 presents GPRS network operations (Mobility Management functions, paging,packet routing and transfer functions)- chapter 4 deals with GPRS Alcatel architecture and describes the consequences of thisarchitecture on telecom layers.- chapter 5 describes specific functions related to MS-network interface- chapter 6 describes specific functions related to Gb interface- chapter 7 describes O&M interface, telecom entity and performance management.- chapter 8 describes some GPRS overall scenario- chapter 9 presents telecom functional blocks which are used in telecom layer specifications- chapter 10 is the glossary


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 7/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

2. GENERAL INTRODUCTION TO GPRS

(see [1])

2.1 Introduction

In many software applications (e.g. web server consultation), data traffic is bursty (i.e. a session maylast several minutes, whereas data is only transmitted during a few seconds).Data transmission in circuit-switched mode has the drawback to allocate resources during the wholesession, General Packet Radio Service (GPRS) defines a network architecture dedicated to packettransfer mode, with radio access, which allows service subscriber to send and receive data in anend-to-end packet transfer mode, without utilizing network resource in circuit-switched mode.A GPRS network can be linked to different fixed data networks (e.g. IP, X25).GPRS uses the BSS architecture, but defines a fixed network (GPRS backbone) which is differentfrom the NSS, and which links the BSS to PDNs (Packet Data Networks).The BSS is used for both circuit-switched and GPRS services.The BSS has 2 clients:

- the MSC, for circuit-switched services (A interface)- the GPRS backbone network, for GPRS (Gb interface)

PDNe.g. X25

GPRSBackbone

BSS

MSC/VLR PSTN

PDNe.g. IP

A

Gb

Gi

Gi

Figure 1 GPRS, gen eral architecture

New GPRS radio channels are defined, and the allocation of these channels is flexible, from 1 to 8radio interface timeslots can be allocated per TDMA frame, timeslots are shared by the active users,and up and downlink are allocated separately.The radio interface resources can be shared statically or dynamically between CS and PS traffics asa function of service load or operator preference.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 8/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

2.2 General architecture

GPRS backbone is an IP network and is composed of routers:- Serving GPRS Support Node (SGSN), at the same hierarchical level as the MSC, which is

linked to several BSSs. It keeps track of the individual MS’s location and performs security functionsand access control.

- Gateway GPRS Support Node (GGSN), which is linked to one or several data networks,provides interworking with external packet-switched networks and is connected with SGSNs via anIP-based GPRS backbone network.

other PLMN

PLMN

IP-based GPRSbackbone

BSS

BSS

SGSN

SGSN

GGSN PDN

GGSN PDN

GGSN

Figure 2 GPRS b ackbone architecture


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 9/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

2.3 GPRS interfaces

The following figure shows new interfaces which have been introduced for GPRS needs.

other PLMN

Gs Gr

GfGp

SGSN GGSN PDN

HLRMSC/VLR

BSS

SGSNSGSN

Gb Gn Gi

Gc

signalling and data interface

signalling interface

Figure 3 GPRS interf aces

- Gr: SGSN-HLR interfaceMAP (Mobile Application Part), TCAP, SCCP, MTP3/2(update/cancel location)

- Gs: MSC/VLR-SGSN interfaceBSSAP+ (Base Station System Application Part +), SCCP, MTP3/2(attach, update location, circuit paging)

- Gf: SGSN-EIR interfaceMAP (Mobile Application Part), TCAP, SCCP, MTP3/2

- Ge: GGSN-HLR interfaceMAP (Mobile Application Part), TCAP, SCCP, MTP3/2

- Gn: SGSN-GGSN interfaceGTP, UDP, IP(PDP context creation/deletion/modification, route monitoring)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 10/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

2.4 Protocol layers

2.4.1 Transmission plane

The transmission plane consists of a layered protocol structure providing user information transfer,along with associated information transfer control procedures (e.g. flow control, error detection andrecovery,..)

GSM-RF

UDP/TCP

SNDCP

L1bis

application

IP/X25

SNDCP

GSM-RF

MAC

RLC

LLC

MS BSS

BSSGP

L1bis

RLC

MAC

NS

BSSGP

NS

SGSN

LLC

relay

relay

L2

L1

GTP

UDP/TCP

IP

IP/X25

GTP

IP

GGSN

L2

L1

Um Gb Gn

Figure 4 GPRS transmission plane

- GTP (GPRS Tunnelling protocol):This protocol tunnels user data and signalling between GPRS support nodes, in the GPRS

backbone network.

- TCP (Transmission Control Protocol):It carries GTP PDUs in the GPRS backbone network for protocols that need a reliable data

link (e.g. X25)

- UDP (User Datagram Protocol):It carries GTP PDUs in the GPRS backbone network for protocols that do not need a reliable

data link (e.g. IP)

- IP (Internet Protocol):This is the GPRS backbone network used for routeing user data and control signalling.

- SNDCP (SubNetwork Dependent Convergence Protocol):It maps network-level characteristics onto the characteristics of the underlying network.

- LLC (Logical Link Control):This layer provides a highly reliable ciphered logical link which is independent of the

underlying radio interface protocols.

- BSS-relay:This function relays LLC PDUs between the Um and Gb interfaces.

- SGSN-relay:This function relays PDP PDUs between the Gb and Gn interfaces.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 11/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

- BSSGP (Base Station System GPRS Protocol):This layer conveys routeing and QoS related information between BSS and SGSN.

- NS (Network Service):It transports BSSGP PDUs and is based on frame relay connection between BSS and SGSN.

- RLC/MAC (Radio Link Control/ Medium Access Control):RLC provides a radio-solution-dependent reliable link and MAC controls the access signalling

procedures for radio channel, and the mapping of RLC frames onto the GSM physical channel.

- GSM-RF layerIt is the radio subsystem which supports a certain number of logical channels

2.4.2 Signalling plane

The signalling plane consists of protocols for control and support of the transmission plane functions:- controlling the GPRS network access connections such as attaching to and detaching from

the GPRS network- controlling the attributes of an established network access connection, such as activation of

a PDP address- controlling the routing path of an established network connection in order to support user

mobility- controlling the assignment of network resources to meet changing user demands- and providing supplementary services

GSM-RF

UDP

GMM/SM

L1bis

GMM/SM

GSM-RF

MAC

RLC

LLC

MS BSS

BSSGP

L1bis

RLC

MAC

NS

BSSGP

NS

SGSN

LLC

relay

relay

L2

L1

GTP

UDP

IP

GTP

IP

GGSN

L2

L1

Um Gb Gn

Figure 5 GPRS signalling plane

- GMM/SM (GPRS Mobility Management/ Session Management)This protocol supports mobility management functionality such as GPRS attach, GPRS

detach, security, routing area update, PDP context (de)activation.

- GTP (GPRS Tunneling Protocol)This protocol tunnels user and signalling messages between SGSNs and GGSNs and

between SGSNs, in the GPRS backbone network.

- UDP (User Datagram Protocol)This protocol transfers signallling messages between GSNs.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 12/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

3. GPRS NETWORK OPERATION

3.1 Definitions

3.1.1 GPRS Mobile station classes

Three MS class modes are defined:- class A: supports simultaneously GPRS and circuit switched services- class B: supports simultaneous attach, but not simultaneous traffic- class C: supports only non-simultaneous attach.

3.1.2 IMSI (International Mobile Subscriber Identity)

An IMSI is allocated to each mobile subscriber in GSM. This is also the case for GPRS-only mobilesubscribers.

3.1.3 P-TMSI (Packet Temporary Mobile Subscriber Identity)

A P-TMSI is allocated to each GPRS-attached MS.It has only a local significance: defined per routing area (i.e. within a SGSN)It is used in the GMM sub-layer for identification of an MS.

3.1.4 TLLI (Temporary Logical Link Identity)

Between the MS and the SGSN, TLLI unambiguously identifies the logical link.It is used for addressing purposes at the RR sub-layer.Within a routing area, there is a one-to-one correspondence between TLLI and IMSI that is onlyknown in the MS and SGSN.TLLI is derived from a P-TMSI and does then provide user identity confidentiality.There are 4 types of TLLIs:

- Local TLLI: derived from the P-TMSI allocated by the SGSN and only valid in the RAassociated to the P-TMSI

- Foreign TLLI: derived from a P-TMSI allocated in another RA- Random TLLI:selected randomly by the MS, when the MS has no valid P-TMSI- Auxiliary TLLI: used for an anonymous access

3.1.5 Location Area Identity (LAI)

In GSM, a LAI identifies one or several cells.The MS is paged in the LA where the MS is located when a terminating call arrives in the MSC.A LA is served by only one VLR.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 13/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

3.1.6 Routeing Area Identity (RAI)

For GPRS, as paging is more frequent than in GSM, Routeing Areas (RA) have been defined, whichare smaller than LAs.A RAI identifies one or several cells.The location of an MS in STANDBY state ( see 3.3.1) is known in the SGSN on a RA level. Thismeans that the MS is paged in the RA where the MS is located when mobile-terminated trafficarrives in the SGSN.A RA is a sub-set of one, and only one, Location Area (LA). A RA is served by only one SGSN.

3.2 Session management

3.2.1 Attach/Detach procedures

In order to access the GPRS services, an MS shall first make its presence known to the network, byperforming a GPRS-attach to the SGSN.This operation establishes a logical link between the MS and the SGSN, and makes the MS availablefor paging via SGSN and notification of incoming GPRS data.

3.2.1.1 Attach procedure

In the attach procedure the MS provides its identity and an indication of the type of attach (GPRS-attach or combined GPRS/IMSI attach).The identity provided to the network is

- either the P-TMSI (if the MS has a valid P-TMSI)- or the IMSI

At the RLC/MAC layer, the MS identifies itself with a TLLI (a Foreign TLLI if a P-TMSI is available ora Random TLLI if valid P-TMSI is not available).The Foreign or Random TLLI is used as an identifier during the attach procedure until a new P-TMSIis allocated.GPRS attach function is similar to IMSI attach

- MS authentication- ciphering key generation- TLLI allocation (derived from the new P-TMSI)- subscriber profile request to the HLR

After having executed the GPRS attach,- the MS is in STANDBY state and may activate PDP contexts- MS location is tracked (RA accuracy)- communication between MS and SGSN is secured- charging information is collected- HLR knows MS location in accuracy of the SGSN

3.2.1.2 Detach procedure

The detach function allows an MS to inform the network that it wants to make a GPRS and/or IMSIdetach and the network to inform an MS that it has been GPRS-detached or IMSI-detached by thenetwork.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 14/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 3.2.2 PDP context

A PTP (Point-To-Point) GPRS subscription contains the subscription of one or more PDP (PacketData Protocol) addresses.Each PDP address is described by an individual PDP context in the MS, the SGSN and the GGSN.The PDP state indicates whether the PDP address is activated for data transfer or not.

- inactivate: no routing information- activate: contains mapping and routing information for transferring PDUs, between MS

and GGSN.The PDP context is updated according to changed subscriber location initiated by MM procedures.

In order to send and receive GPRS data, the MS shall activate the PDP address that it wants to use.This operation makes the MS known in the corresponding GGSN, and interworking with external datanetworks can begin.User data is transferred transparently between the MS and the external data networks (encapsulationand tunnelling)

3.2.2.1 Activation procedure

(4)

Create PDP context request (3)

(2)

GGSNSGSNMS

Create PDP context response (5)Activate PDP context accept (6)

Activate PDP context request (1)

Figure 6 PDP context activation procedure

- (1): MS sends activation request to SGSN- (2): SGSN verifies the subscription information of MS- (3): SGSN informs GGSN about new PDP type and address- (4): GGSN creates a context and- (5): GGSN acknowledges the SGSN- (6): SGSN acknowledges the MS

When a PDP context is activated- SGSN has a logical bidirectional tunnel between the MS and the GGSN- GGSN has a PDP address activated and mapped to the MS- Location of the MS is known in accuracy of SGSN- Mobile originating and Mobile terminating data transmission is now possible

3.2.2.2 Deactivation procedure

PDP context deactivation can be initiated either by the MS or by the SGSN, or by the GGSN.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 15/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

3.3 Mobility Management

Mobility Management (MM) is handled in a specific way through GPRS network.To be known from GPRS network and to transmit data, a MS has to undertake an attach procedureand then to activate a PDP context, in order that its SGSN address is known by GGSNs.

3.3.1 MM states

The MM activities related to a GPRS subscriber are characterised by the following states:

- IDLEThe subscriber is not attached to the GPRS MM, paging is not possible.The subscriber is not known from the different GPRS nodes.The MM context holds no valid location or routing information for the subscriber.

- STANDBYThe subscriber is attached to GPRS MM.CS and PS paging are possible but data transmission and reception are not possible.The SGSN MM context contains only the RAI location information.The MS may initiate activation or deactivation of PDP contexts while in this state.

- READYAfter paging, the MM state in the SGSN is changed to READY when data or signallinginformation is received from the MS.The location information in the SGSN MM context is extended to cell level.The MS may send and receive data in this state.Regardless if a radio resource is allocated to the subscriber or not, the MM context remains

in the READY state even when there is no data being communicated.The READY state is supervised by a timer. When it expires, the state becomes STANDBY.

3.3.2 Location Management Function

The network provides information to the MS to:- detect when it has entered a new cell or a new RA- determine when to perform periodic RA updates

When a MS camps on a new cell, one of these 3 scenarios may occur:- a cell update is requiredwhen the MS enters a new cell inside the current RA and the MS is in READY state- a routing area update is requiredwhen GPRS-attached MS detects it has entered a new RA or when the periodic update timerhas expired- a combined routing area and location area is required(only in network operation mode I), when

- a GPRS-attached MS, which has an IMSI attach to perform, enters a new RA- the periodic RA update timer expires while the MS shall remain IMSI attached


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 16/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

3.4 Interactions between SGSN and MSC/VLR

This interaction needs the presence of the Gs interface, which provides interactions between SGSNand MSC/VLR.The association supports the following actions:

- IMSI attach and detach via SGSN (combined GPRS/IMSI attach/detach are possible)- coordination of LA and RA update (combined RA/LA update)- paging for a CS connection via the SGSN

3.4.1 Paging coordination

The network may provide coordination for paging CS and PS.Paging coordination means that the network sends paging CS messages on the same channel asused for PS paging messages (i.e. on the GPRS paging channel or the GPRS traffic channel).Three network operation modes are defined:

- network operation mode IThe network sends a CS paging message for a GPRS-attached MS, either on the same channel asthe GPRS paging channel (i.e. the packet paging channel or the CCCH paging channel), or on aGPRS traffic channel.This means that the MS needs only to monitor one paging channel and that it receives CS pagingmessages on the PDCH (PACCH) when it has been assigned a TBF.

PPCH/PCHPS Paging

CS Paging

SGSN

BSS

MSC

BTS

Gs

Figure 7 Network op eration mode I, with PCCCH or CCCH


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 17/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

CS Paging

SGSN

BSS

MSC

PACCH

BTS

Gs

Figure 8 Network op eration mode I, MS in packet transfer mode

- network operation mode IIThe network sends a CS paging message for a GPRS-attached MS, on the CCCH paging channel,and this channel is also used for GPRS paging.This means that the MS needs only to monitor the PCH, but that CS paging continues on the PCHeven if the MS has been assigned a PDCH.

CS Paging

PS Paging

SGSN

BSS

MSC

BTS

PCH

Figure 9 Network op eration mode II


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 18/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

- network operation mode IIIThe network sends a CS paging message for a GPRS-attached MS, on the CCCH paging channel,and sends a GPRS paging message on either the packet paging channel (if allocated in the cell) oron the CCCH paging channel.This means that a MS that wants to receive pages for both CS and PS shall monitor PCH and PPCH(if there is a MPDCH).

CS Paging

PPCH

BTS BSSPCH

MSC

PS Paging

SGSN

Figure 10 Network mode op eration III

Note: If there is no MPDCH, same case than mode II

The following table gives the characteristics of the 3 modes:

Mode Circuit Paging Channel GPRS Paging Channel CharacteristicsPCCCH PCCCH - Gs interface

- MPDCH(see Figure 7)

I CCCH CCCH - Gs interface- no MPDCH- BSCGP interface(see Erreur! Sourcedu renvoiintrouvable. )

Packet data channel (not applicable) - Gs interface(see Figure 8)

II CCCH CCCH - BSCGP interface- no MPDCH- no Gs interface(see Figure 9)

III CCCH PCCCH - MPDCH- no Gs interface(see Figure 10)

CCCH CCCH - no MPDCH- BSCGP interface- no Gs interface(see Figure 9)

The network operation mode is notified to the MS either in PSI1 or in SI3.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 19/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 3.4.2 Paging for GPRS downlink transfer

An MS in STANDBY state is paged by the SGSN before a downlink transfer to that MS.At the response of the paging (any LLC PDU), the MM state moves to READY and the downlinktransfer begins.

GPRS Paging request (2)Paging request (1)

PDP PDU

SGSNBSSMS

STANDBY

any LLC PDU (3)any LLC PDU (4)

READY

Figure 11 GPRS paging procedure

- (1): On reception of a downlink PDP PDU, in the STANDBY state, the SGSN sends a BSSGPpaging request, with the IMSI (to calculate the MS paging group), the P-TMSI (identifier bywhich the MS is paged), the Routing Area (determine the set of cells to be paged), QoS (notused in B6.2) and the DRX parameters

- (2): The BSS pages the MS with one message in each cell belonging to the Routing Area

- (3): The MS responds with any LLC PDU which is interpreted by the SGSN as a page response.

- (4): The BSS adds the cell identity.

3.4.3 Paging for CS connection establishment

CS paging are received from the SGSN, only in network operation mode I.When a MS is attached to GPRS, the MSC/VLR executes paging for circuit-switched services viaSGSN. Class A and B MSs have the capability to receive CS page while attached to GPRS.If the MS is in STAND-BY state, then it is paged in the routeing area.If the MS is in READY state, then it is paged in the cell.Upon receipt of a paging request message for a circuit-switched service, the MS may accept torespond to this request and shall then follow the CS procedures for paging response.When received at the BSS, the paging response message is sent to the MSC.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 20/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

4. ALCATEL ARCHITECTURE

(see also [20])

4.1 BSS architecture

4.1.1 PCU Concept

A Packet Control Unit (PCU) has been defined in [1], where are implemented RLC/MAC functions:- LLC layer PDU segmentation into RLC blocks for downlink transmission- LLC layer PDU reassembly from RLC blocks for uplink transmission- PDCH scheduling functions for the uplink and downlink data transfers- downlink and uplink ARQ (Automatic Retransmission Request) functions- channel access control functions (e.g. access request and grant)- radio channel management functions (e.g. power control, congestion control, broadcastcontrol information)

A PCU controls the GPRS activity of one cell.

The functions implemented, inside the Channel Codec Unit (CCU) are:- channel coding functions, including FEC (Forwarding Error Correction) and interleaving- radio channel measurement functions, including received quality level, received signal level

and information related to timing advance measurements.The CCUs are implemented in the BTS.

The position of the PCU may be (see Figure 12)- either at the BTS site- or at the BSC site- or at the SGSN site

When the PCU is positioned remote to the BTS, the information between the CCU and the PCU istransferred in frames with a fixed length of 320 bits.A frame shall be transferred between the PCU and the CCU, every 20 ms.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 21/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

BTS

Gb

Gb

Abis

BTS

BTS

CCU

CCU

CCU

CCU

CCU

CCU

PCU

BSC site SGSN site

PCU

PCU

circuit-switching function(16 or 64 kbit/s)

packet-switching function

Figure 12 PCU impl ementat ions


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 22/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 4.1.2 ALCATEL implementation

The Alcatel approach for the implementation of GPRS in the BSS consists of a smooth and costeffective introduction of GPRS by minimizing the hardware modification needed to the alreadyinstalled network elements (i.e. BTS and BSC).To this end, a new network element, the MFS, supporting nearly all the GPRS specific functions ofthe BSS, defined in the GPRS standard:

- PCU function- standard Gb interface protocol stack

is introduced.

From the BTS perspective, the radio channels can be dynamically configured as TCH or PDCH.

The MFS is connected to the BSC by means of already installed Ater physical lines.

In order to support low GPRS traffic load, in a more optimized way, the transmission resources canbe shared between GPRS and circuit-switched traffic

Gb

Ater

CCU

CCU

CCU

CCU

SGSN

BSC

BSCBTS

BTS

Um

Abis

MFS

PCU

PCU

Figure 13 ALCATEL BSS architecture


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 23/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

Some GPRS functionalities have consequences on the transmission and control planes of the Alcatelarchitecture.

- PCU locationSince PCU functionalities are located in the MFS, GSM-RF layer has to be extended to the MFS(L1/L2 GCH layer) (see Figure 14 and Figure 15)

- GPRS common signallingFor GPRS common signalling needs, either CCCH (which is used for circuit-switched traffic) or adedicated channel PCCCH is used.When CCCH is used, for GPRS common signalling, a signalling link has to be established betweenthe MFS and the BSC (L1/L2 GSL and BSCGP) (see Figure 16)

- Radio resources dynamic allocationRadio and Abis resources are shared between circuit-switched and GPRS traffic, therefore asignalling link has to be established between the MFS and the BSC (L1/L2 GSL and BSCGP) toallow resources request. (see Figure 16)

4.1.3 Transmission plane

Two proprietary layers are implemented to extend the radio interface to the MFS (see Figure 14):- L1-GCH is the physical layer which uses a synchronous mode of transmission (16 kbit/s)- L2-GCH consists in a protocol between the MFS and the BTS for synchronisation with the

radio interface and channel activation.GCH links go through the BSC transparently.

SNDCP

BSSGP

L1bis

application

IP/X25

SNDCP

GSM-RF

MAC

RLC

LLC

BSSGP

NS

L1bisL2-GCH

L1-GCHGSM-RF

relay L2-GCH

L1-GCH

RLCrelay

MAC

MS BTS MFS SGSN

NS

LLC

Um Abis/Ater Gb

Figure 14 BSS transmission plane


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 24/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 4.1.4 Control plane

4.1.4.1 Control plane, with PCCCH usage

In this case, CCCH is not used, by GPRS functions and the BSC is transparent for GPRS commonsignalling (see Figure 15).

- GMM/SM (GPRS Mobility Management/Session Management)This protocol supports mobility management functionality such as GPRS attach/detach,security, routeing area update, location update, PDP context activation/deactivation.

- RRM (Radio Resource Management) layer provides services for packet connectionmanagement, for radio resource management and for paging requests routing.

RR/RRM RRM

RLC

relay

BSSGP

L1bis

GSM-RF

MAC

BSSGP

NS

L1bisL2-GCH

L1-GCHGSM-RF

relay L2-GCH

L1-GCH

RLC

MAC

MS BTS MFS SGSN

NS

LLC LLC

GMM/SM GMM/SM

Um Abis/Ater Gb

Figure 15 BSS control plane (with P CCCH)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 25/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

4.1.4.2 Control plane, with CCCH usage

In this case, BSC signalling layers are concerned, in the connection establishment phase to accessto CCCH, for GPRS common signalling (see Figure 16):

- L1-RSL is the physical layer. It uses 64 or 16 kbit/s channels.- L2-RSL consists of a LAP-D protocol.- L1-GSL uses 64 kbit/s channels- L2-GSL consists of a LAP-D protocol, doubled for redundancy reasons.- BSCGP (Base Station Controller GPRS Protocol) conveys routeing of GPRS relatedmessages (GPRS paging messages, MS originated channel request, immediate assignment)when the CCCH is used for GPRS signalling and handles channel allocation for GPRS

needs.

RR/RRM

RRBSCGP

RRM

L1bis

GSM-RF

MS

L2-RSL

L1-RSLGSM-RF

relay

BTS

BSCGP

L1-GSL

L2-RSL

L1-RSL

relay

BSC

L2-GSL L2-GSL

L1-GSL

MFS

BSSGP

NS

LLC

GMM/SM

Um Abis Ater Gb

Figure 16 BSS control plane (without P CCCH)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 26/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

4.1.5 Physical interfaces

4.1.5.1 Principles

A

MFS

GCH

GSL

MSC

BSC

SM SMTC

Abis Ater

AterMuxAter

16 kbit/s on 64 kbit/s circuit



SM: Sub Multiplexer

TC: TransCoder (speech transcoding)

SGSN

Gb

signalling n° 7

Figure 17 BSS physical interface

- Abis interface: This interface is used both for CS and GPRS traffic.With G2 BSC, resources are dynamically allocated either to GPRS traffic or

to circuit-switched traffic.16kbit/s channels are dynamically switched by the BSC between Abis andAter interfaces.

- Ater interface: This interface is used both for CS and GPRS traffic.On this interface, two functionally different types of channels are used, forGPRS traffic:- GPRS Signalling Links (GSL) for signalling purposes between the BSC andthe MFS (not supported by G1 BSC)One GSL channel consists of one 64 kbit/s LAPD channel. For redundancyreason it is duplicated.they are used for:

- dynamic configuration of radio timeslots- CS/PS paging, GPRS access procedure (when CCCH is used)- O&M purposes

- GPRS traffic Channels (GCH) carrying the GPRS traffic between the MFSand one GPRS radio timeslot in the BTS (16 kbit/s)GCH channels are dynamically through connected by the BSC between Abisand Ater interfaces.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 27/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

- AterMux interface: On this interface, 16 kbit/s channels are multiplexed on 64 kbit/s circuits.This interface is used for circuit-switched and GPRS traffic.These multiplexed 16 kbit/s channels are called “nibbles”.

SM

tributary 2

tributary 3

tributary 4

TS

tributary 1TS

(4 nibbles)

Ater interface AterMux interface

TS: 64 Kbit/s Time-Slot

Figure 18 4:1 multiplexing scheme


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 28/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

The AterMux PCM is composed of 32 timeslots at 64kbit/s, shared between CS timeslots and GPRStimeslots.• The CS timeslots are made up of:- timeslots composed of 3 or 4 CS nibbles at 16kbit/s (according to the multiplexing scheme 3:1 or

4:1 of the BSC); a CS nibble carry the voice for a transaction- CS signalling N7- other specific O&M timeslots not related to CS (X25, Qmux, Alarm octet)

• The GPRS timeslots on the AterMux contain:- the timeslots devoted to the transport of GPRS data composed of 3 or 4 GPRS nibbles at

16kbit/s- the GPRS signalling channels (64k) called GSL channels

CS nibbles

N7 signalling link(s)

X25 , Alarm octet, Qmux

GSL link(s)

PCM linkbetween BSC

and MFS(AterMux)

GPRS

CIRCUITSWITCHED

datanibbles

Figure 19 Mixed CS/GPRS AterMux composition

When the AterMux is mixed CS/GPRS, the CS timeslots are cross-connected transparently towardsthe MFS-TC interface in order to transcode the voice, and the GPRS timeslots are converted into theGb interface protocol to be forwarded to the SGSN. (see Figure 20)

- Gb interface: The Gb physical interface consists of one or more 64 kbit/s time-slots.They can be carried by the MFS-SM/TC AterMux interface or by direct 2048kbit/s links to the SGSN.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 29/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

4.1.5.2 Connection types

4.1.5.2.1 Ater interface

The MFS main entity is the GPU board.Each GPU board can be connected to one BSC.As the MFS should be localised in the same place as the MSC, it may use, for GPRS traffictransport, the existing Ater resources between the BSC and the TC/MSC sites.Two options can be taken:

- PCM fully dedicated to GPRS traffic

- mixed CS/GPRS PCMThis is performed by allocating some of the Ater timeslots for GPRS traffic.CS timeslots are routed transparently through the MFS.(see Figure 20)

AterMux

PCM

MFS

MSCBSC

CS circuit

SGSN

Gb

Figure 20 Mixed CS/GPRS PCM


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 30/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

4.1.5.2.2 Gb interface

For MFS to SGSN connections, 3 options can be taken:

1) combined AterMux links and Gb links through TC and MSC (see Figure 21)- CS timeslots are routed transparently through the MFS- GPRS timeslots are processed in the MFS and replaced by Gb timeslots- GPRS timeslots are set as “transparent” in the TC

Gb

SGSN

PCM

BSC

CS circuit

MFS TC MSC

Figure 21 Combined CS/Gb PCM

2) Gb links direct from MFS to SGSN

3) Gb links between MFS and SGSN through MSC (see Figure 22)- a PCM is dedicated to Gb interface- GPRS timeslots are processed in the MFS and replaced by Gb timeslots

Gb

BSC

MFS

PCM

SGSN

MSC

Figure 22 Gb links through the MFS

(all the 3 options may use a synchronous frame relay network to access the SGSN)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 31/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

4.2 GPRS global architecture

The Alcatel GPRS architecture is depicted Figure 23:

GbBSS

Gs

BTS BSC MFS

MSC/VLR

OMC-R

SGSN GGSN

HLR

Gr

Gn

1 to n relation

Figure 23 GPRS architecture

The main characteristics are the following:- All the BSS connected to the same MFS are managed by the same OMC-R- All the BSS connected to the same MFS can be connected to different MSCs, provided

they are located on a same site.- All the BSS connected to the same MFS are connected to the same SGSN

- Gs interface:Through this interface, an association is created between SGSN and MSC/VLR to provide forinteractions between SGSN and MSC/VLR.

The association is used for coordinating MSs that are both GPRS-attached anf IMSI attached(coordination of LA and RA update, CS paging via SGSN,...)When this interface is present, Network operates in mode I (see 3.4.1)

- Gn interfaceInterface between GSN nodes in the GPRS backbone network.The GTP on this interface includes both signalling and data transfer procedures.

- Gr interfaceInterface between SGSN and HLR.MM procedures use MAP protocol on this interface.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 32/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5. GPRS RADIO INTERFACE

5.1 Interfaces description

(see [2] and [3])

The following figure sums up MS-network interface, in Alcatel implementation:- Packet data transfer and associated signalling is carried on GCH links.- GPRS common signalling is carried either by GCH links, if PCCCH exists or by GSL/RSLlinks, if PCCCH doesn’t exist.- Resource management is handled through GSL links

Um

- Packet data transfer and associated signalling- common signalling on PBCCH/PCCCH

GCH

commonsignallingon CCCH

L2-RSL

PDTCH

PCCCH

PBCCH

GSM-RF

L1-RSL

L1-GCH

L2-GCH

CCCH

BCCH

BTS BSC

Abis

GSL

- commonsignallingon CCCH- (M)PDCH(de)alloc.- cell/BSC/CICstate change

L1-GCH

L2-GCH

BSCGP

RRM

L1-GSL

L2-GSL

MAC

RLC

MFS

Ater

L1-RSL

BSCGP

L1-GSL

L2-GSLL2-RSL

Figure 24 MS-Network interface


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 33/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5.2 Um interface

5.2.1 GSM-RF layer

The purpose of this layer is to provide communication between the MSs and the BTS.This layer supports multiple MSs sharing a single physical channel.

This layer is responsible for:- Forwarding Error Correction (FEC) coding, allowing the detection and correction of

transmitted code words and the indication of uncorrectable code words.- rectangular interleaving (on the radio interface)

This layer control functions include:- synchronisation procedure, including means for determining and adjusting the MS timingadvance.- monitoring and evaluation procedures for radio link signal quality- cell (re)selection procedure- transmitter power control procedures- discontinuous reception procedures


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 34/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 5.2.2 packet data logical channels

The access scheme is Time Division Multiple Access (TDMA) with eight basic physical channels percarrier (TS 0 to 7).A GPRS time-slot is named a “Packet Data CHannel” (PDCH)

50 51

1 (52-frame) multiframe = 52 TDMA frames (240 ms)

49483210

0 2 7 0 2 7 0 2 7

1 TDMA frame = 8 TS (4,615 ms)

Figure 25 Time slots and f rames

A PDCH is mapped dynamically on a 52-multiframe.The 52 multiframe consists of 12 blocks of 4 consecutive frames, 2 idle frames (frames 25 and 51)and 2 frames used for the PTCCH (frames 12 and 38).

frame 0 4 8 12

13 17 21 25

26 30 34 38

39 43 47 51

block B0 B1 B2 B3 B4 B5 x B6 B7 B8 B9 B10 B11 x

Figure 26 52- multif rame


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 35/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

Different packet data logical channels can occur on the same physical channel (i.e. PDCH). Thesharing of the physical channel is based on blocks of 4 consecutive bursts.

- PCCCH (Packet Common Control Channel)This channel deals with common control (paging, access grant, random access)It does not have to be allocated permanently in the cell. Whenever the PCCCH is not allocated, theCCCH shall be used to initiate a packet transfer.When it exists, the PCCCH is mapped on one or several PDCHs (only one in step1). In that case, thePCCCH, PBCCH and PDTCH share same PDCHs.The PCCCH supports the following sub-channels:

- PRACH (Packet Random Access CHannel)PRACH is determined by the USF (see 5.5.4.1) that is broadcast continuously on the correspondingdownlink.

- PPCH (Packet Paging CHannel)- PAGCH (Packet Access Grant CHannel)

- PBCCH (Packet Broadcast Control Channel)It broadcasts general information used by the MS to access the network for packet transmission andinformation (transmitted on BCCH) to allow CS operation.It does not have to be allocated permanently in the cell.It is mapped on one or several PDCHs (only one, in step1). The mapping on the PDCH follows apredefined rule.The existence of the PCCCH, and consequently the existence of the PBCCH, is indicated on theBCCH.

- PTCH (Packet Traffic Channel)It is used for user data transmission and its associated signalling

- PDTCH (packet Data Traffic CHannel)It is mapped onto one PDCH. up to 8 PDTCHs, with different timeslots but with the same

frequency parameters, may be allocated to one MS at the same time.- PACCH (Packet Associated Control CHannel)It is mapped onto one PDCH. It is dynamically allocated on the block basis.If a single PDTCH is assigned to one MS, the corresponding PACCH is allocated on the

same PDCH.If multiple PDTCHs are assigned to one MS, PACCH is always allocated on one of the

PDCHs on which PDTCHs are allocated. the position of the PDCH carrying the PACCH is providedexplicitly in the resource assignment message.

PACCH is bi-directional (i.e. it can dynamically be allocated both on the uplink and on thedownlink regardless on whether the corresponding PDTCH assignment is for uplink or downlink)

- PTCCH (Packet Timing advance Control Channel)This bi-directional channel is used for continuous timing advance mechanism.The PDCH carrying the PTCCH of one MS is the same PDCH carrying the PACCH of that MS.A MS shall be allocated a sub-channel of the uplink PTCCH according to the Timing Advance Index(TAI). (see 5.2.5.2)

- burst typesOn PRACH access bursts are used. On all other packet data logical channels, radio blockscomprising 4 normal bursts are used. The only exception is the Packet Control ACK message onuplink PACCH which comprise 4 consecutive access bursts.

- GPRS master channel (MPDCH)A PDCH will be called “master GPRS channel” when it carries PBCCH and PCCCH channels.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 36/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

Two cases have to be foreseen:

5.2.2.1 no GPRS master channel

In this case, BCCH and CCCH are used both for circuit-switched traffic and packet traffic.So BSC has to forward uplink CCCH flow either towards the MSC or the MFS.

PTCH (PDTCH, PACCH)

BCCH

CCCH (PCH, AGCH)

PTCH (PDTCH, PACCH)

CCCH (RACH)

BTSMS MFSBSC

GCH (GPRS CHannel)

RSL (Radio Signalling Link)

GSL (GPRS Signalling Link)

PTCCH

Figure 27 GPRS logical channels (without GPRS master channel)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 37/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5.2.2.2 GPRS master channel presence

In this case, information flow goes transparently through the BSC.GPRS master channel is defined thanks to BCCH system information.

PTCH (PDTCH, PACCH)

BCCH

PCCCH(PPCH, PAGCH)

PTCH(PDTCH, PACCH)

PCCCH (PRACH)

BTSMS MFSBSC

GCH (GPRS CHannel)

PBCCH

PTCCH

Figure 28 GPRS logical channels (with GPRS master channel)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 38/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 5.2.3 Channel coding

On the radio interface, data can be coded according to four different coding schemes, CS1 to CS4(CS3 and CS4 are not part of the GPRS step 1).These coding schemes offer different redundancy levels.

CS RLC data block(RLC header + RLC data)

(bytes)

RLC data unit

(bytes)

RLC data unitthroughput

(kbit/s)CS1 22 20 8CS2 32 30 12CS3 38 36 14,4CS4 52 50 20

RLC/MAC blockMAC header (1 byte) RLC header (2 bytes) RLC data unit spare bits

RLC data block without spare bits

CS1 is always used for signalling. (it is the most protected CS)CS1 and CS2 can both be used for traffic, depending on radio conditions.This choice is done by the MFS (RRM/RLC layer), according to

- reception quality- and level measurements performed by the BTS,

and coding is applied, on the radio interface, on RLC/MAC PDU + BCS (Block Check Sequence);In the UL, the coding scheme is transmitted to the MS in the TBF establishment phase.If the MFS decides to change the coding scheme, it sends an extra PACKET UL ACK/NACKmessage to the MS.An O&M parameter allows to enable/disable the CS adaptation mechanism.

O&M

BTS type

uplink flow

RXQUAL/RXLEV

MS BTS MFS

channel coding codingschemedetermination

receptionmeasurements

codingscheme

Figure 29 Channel coding

Note: FUMO BTS handles only CS1


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 39/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 5.2.4 Cell re-selection

The MS performs autonomous cell re-selection (NC0).The MS shall measure the received signal strength on the BCCH frequencies of the serving cell andthe neighbour cells, as indicated in the BA-GPRS list, and calculate the received level average ofeach frequency.MS applies either existing GSM reselection parameters, in case of cell without PBCCH or GPRSreselection parameters in case of cell with PBCCH.

5.2.5 Timing advance

The timing advance procedure is used to derive the correct value for timing advance that the MS hasto use for the uplink transmission of radio blocks.The timing advance procedure comprises 2 parts:

- initial advance estimation- continuous timing advance update

5.2.5.1 Initial timing advance estimation

5.2.5.1.1 Uplink data transfer

It is based on BTS measurements, on the single access burst carrying the Packet Channel Request.The Packet UL Resource Assignment then carries the estimated timing advance value (TA) to theMS. This value shall be used by the MS for the uplink transmissions until the continuous timingadvance update provides a new value.

(PAGCHor AGCH)

(PRACHor RACH)

MS BTS MFS

Packet Channel Request

timing advancecalculation

Packet Channel Request+ timing advance (TA)

Packet ULAssignment ( TA + TAI)Packet UL

Assignment (TA + TAI)

TAIallocation

to be used forcontinuoustiming advanceupdate

TAI:TimingAdvanceIndex

Figure 30 Timing advance mechanisms (UL data transfer)

Note: Data transfer establishment procedures are detailed in 5.5.2.1.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 40/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5.2.5.1.2 Downlink data transfer

In this case a polling indication (see 5.5.4.2) is sent in the Packet DL Resource assignment torequest to the MS a Packet Control ACK as four access bursts, on which the timing advance will becalculated, by the BTS.

Packet control ACK(timing advance)

packetpower/timing update

MS BTS MFS

TAIallocation

LLC PDU

(PACCH)

(PAGCH)

Packet control ACK

timingadvance

calculation

Packet DL assignmentwith polling (TAI)

to be used forcontinuoustiming advanceupdate

Figure 31 Timing advance mechanisms ( downlink data transfer) (MPDCH case)

5.2.5.2 Continuous timing advance update

This procedure is carried only on the PDCH which carries PACCH.For packet transfer ( in Packet DL/UL Assignment), the MS is assigned a Timing Advance Index(TAI) which determines on which uplink frame an access burst has to be sent.The TAI allows 16 different positions in groups of eight 52-multiframes (frames 12 and 38).The BTS analyses the received access burst and determines a new timing value.The new timing advance values are sent via a downlink signalling message (TA-message) mappedon the same frames (12 and 38), which contains timing advance values for all the MSs.Four consecutive TA-messages are identical (i.e. timing advance values are updated only every 4TA-messages).This mechanism works without knowledge of the MS entity by the BTS and there is no need forinteractions between the BTS and the MFS.TA value is updated every 0,96 s (4 x 0,24).


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 41/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

n/12 (52 multi-frame number=n/frame number=12)

TA-message n/38

TAcalculation

n/38

TA-message n+1/12

TAcalculation

n+1/12

TA-message n+1/38

TAcalculation

n+1/38

TA-message n+2/12

TAcalculation

TA-messageupdate

MS BTS

Figure 32 Continuous timing advance update mechanism


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 42/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

The following table shows, according to the TAI value- the position of the uplink PTCH- and the first TA message which will contain the last calculated timing advance

uplink PTCH first TA message where timingadvance is taken into account

TAI 52 multi-frame frame 52 multi-frame frame0 n 12 n+2 121 n 38 n+2 122 n+1 12 n+2 123 n+1 38 n+2 124 n+2 12 n+4 125 n+2 38 n+4 126 n+3 12 n+4 127 n+3 38 n+4 128 n+4 12 n+6 129 n+4 38 n+6 12

... ... ... ..... ....15 n+7 38 n+8 120 n+8 12 n+10 12

Figure 33 Continuous timing advance update scheduling

5.2.6 Power control

For the UL power control, 2 methods can be used:- open loop:For the MS, the output power is based on the received signal strength assuming the same path lossin uplink and downlink.- closed loop:The output power is commanded by the network based on signal strength measurements, made inthe BTS, in a similar way as for CS connection.

Only UL power control in open loop is implemented.When accessing a cell on the PRACH, the MS shall use the output power defined byGPRS_MS_TXPWR_MAX_CCH (maximum allowed output power in the cell), broadcast on PBCCHof the serving cell.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 43/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 5.2.7 Discontinuous reception (DRX)

This function allows a MS not to monitor all PCCCH blocks, but only blocks defined by its paginggroup.Negotiation of DRX parameters is per MS, an MS may choose to use DRX or not together with someoperating parameters given to the SGSN, in the GPRS-Attach message:

- DRX/non-DRX indicator- [DRX period] defined by SPLIT_PG_CYCLE(the DRX period is equal to about 15,36/SPLIT_PG_CYCLE seconds, 15,36 s corresponds to

64 52-multiframes)- [non-DRX timer] time period within which non-DRX mode is kept after leaving the transferstate.

These parameters and the IMSI (which is used to determine the paging group) are sent to the MFS in- page request (to determine on which block the paging request will be sent)- DL blocks (to determine on which block the Packet DL assignment will be sent)

Paging groups are numbered on 64 * 52- multitrames basis.In the following table, an example is shown, where 4 blocks, per 52-multiframe are dedicated forPCCCH (4 x 64 = 256 paging groups).

B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11PBCCH PG 0 PBCCH PG 2 PBCCH PG 1 PBCCH PG 3 0PBCCH PG 4 PBCCH PG 6 PBCCH PG 5 PBCCH PG 7 1

PBCCH PG 252 PBCCH PG 254 PBCCH PG 253 PBCCH PG 255 63PBCCH PG 0 PBCCH PG 2 PBCCH PG 1 PBCCH PG 3 0

PG: Paging Group

Figure 34 paging group configuration example

The MFS determines the paging group from the IMSI value.To reduce paging group periodicity (15,36 s), this period is devided by “SPLIT_PG_CYCLE” value.

When page for CS services is conveyed on PPCH, it follows the same scheduling principles as thepage for packet data

MS applies existing GSM DRX procedures if there is no MPDCH.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 44/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 5.2.8 System information broadcasting

The BCCH indicates whether or not packet switched traffic is supported (RA_COLOUR field in SI3 ispresent if GPRS is supported in the cell), SI13 message shall be sent on BCCH if and only if GPRSis supported in the cell.

There are two distinct cases for the network to convey the relevant information to the MS:- no PBCCH in the cell

The MS uses the common BCCH system information messages for both CS and GPRS services (inthis case it is not possible to indicate to the MS the neighbour cells which effectively support GPRS,nor to use specific reselection parameters for GPRS).SI13 contains all necessary parameters for GPRS.

- PBCCH in the cellBased on BCCH information, contained in SI13, the MS switches directly to the PBCCH, where theMS will get all relevant information broadcast in PSI messages.The MS shall read:

- PSI1 message- a consistent set of PSI2 messages- a consistent set of PSI3 messages and optional PSI3bis message

Consistency of System Information is provided by the following parameters:- PBCCH_CHANGE_MARK (in PSI1 message, its value is changed each time any

information has been changed in other system information messages on PBCCH)- MA/PSI3/.._CHANGE-MARK (in other PSI messages, its value identifies a consistent set of

the PSI group. Its value is changed each time information has been updated in any of the PSIxmessages).

The following GPRS specific System Information is broadcast:- PSI1:

- common parameters- control channel information for GPRS- PBCCH_CHANGE_MARK

(When a MS has read all the GPRS PSI messages once, only PSI1 needs to be read untilPBCCH_CHANGE_MARK value is modified)

- PSI2:- list of PCCCHs- list of mobile allocations

- PSI3:- BA_lists ( BCCH allocation in the neighbour cells)- cell reselection parameters

To avoid that MSs which are involved in a data transfer have to read PBCCH or BCCH,- PSI1 is broadcast on PACCHs, if there is a master PDCH- PSI13 (same information than in SI13) is broadcast on PACCHs, if there is no master

PDCH


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 45/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5.3 BSCGP layer

5.3.1 BSCGP layer functions

In addition to radio resource management, the BSCGP layer is also used for the following purposes:- radio signalling

- CS/PS paging (when there is no GPRS master channel)- channel request/assignment (when there is no GPRS master channel) (see 5.5.2.1.1.2

and 5.5.2.1.2.2)- system control

- GSL reset procedureAfter link recovery, this procedure is performed to synchronize PDCH allocation andentity status information.

- state change indication (related to: cell, BSS, and PCM entities)- traffic control (access class changes)- cell start/stop for GPRS traffic (MFS has to notify this information, in order to broadcast

this information on SI3)

L1-GSL

L2-GSL

BSCGP

L1-GSL

L2-GSL

BSCGP

radio signalling

GPRS radio resource management

system control

BSC MFS

Figure 35 BSC-MFS interface


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 46/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 5.3.2 Radio resource management

A cell supporting GPRS may allocate resources on one or several physical channels (i.e. PDCHs) inorder to support the GPRS traffic.Those PDCHs, shared by the GPRS MSs are taken from the common pool of physical channelsavailable in the cell.

The allocation of physical channels to circuit switched services and GPRS is done dynamicallyaccording to the “capacity on-demand”.Common control signalling required by GPRS in the initial phase of the packet transfer is conveyedon PCCCH, when allocated, or on CCCH.GPRS does not require permanently allocated PDCHs.However, the existence of PDCH does not imply the existence of PCCCH.The information about PCCCH is broadcast on BCCH.

This management is realized, by the RRM layer, through the BSCGP layer (GPRS radio resourcemanagement) (see Figure 36):

- PDCH allocation/deallocation (1)

- PDCHs are always dynamically allocated.- The minimum number of PDCHs (MIN_PDCH_GROUP), the maximum number of

PDCHs under normal BSC load (MAX_PDCH_GROUP) and the maximum number ofPDCHs under high BSC load conditions (MAX_PDCH_HIGH_LOAD) are set by cell via O&M (5).

- Between MIN_PDCH_GROUP and MAX_PDCH_GROUP / MAX_PDCH_HIGH_LOAD,the number of allocated PDCHs fluctuates dynamically, according to:

- circuit-switched traffic load, in the cell- GPRS traffic load, in the cell- a new channel request from a mobile

- When a PDCH is allocated, a link is established at GCH level between the MFS and theBTS (2).- The BSC notifies high and normal cell load conditions to the MFS (3).

An O&M parameter defines, in the BSC, a threshold corresponding to high load indication.Under high BSC cell load conditions, the MFS marks allocated PDCHs, exceeding the

maximum number (MAX_PDCH_HIGH_LOAD), as unavailable for new TBFs. When allTBFs carried by these PDCHs are normally terminated, the PDCHs are deallocated and

corresponding links are released at GCH level (2)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 47/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

- GPRS master channel allocation/deallocation (4)

The dynamic allocation of the GPRS Master channel is not supported in B6.2 (i.e. there is nomeasurement of GPRS signalling load on CCCH to dynamically allocate/deallocate theMPDCH).

The operator configures statically whether a GPRS cell supports or not a MPDCH (6).At cell activation, MFS requests the BSC to allocate one slot which is then afterwards

marked as a master PDCH (4).

(6)(5)

O&M

GCH ch.act/release. (2)

GPRS masterch. alloc/dealloc (4)

PDCHalloc/dealloc.(1)

BSC_LOAD(3)

BTS BSC

masterchannelmanagement

MFS

PDCHmanagement

masterchannelmanagement

packet channelreq/rel.

Figure 36 PDCH and GPRS master channel management


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 48/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5.4 GCH layer

This layer has to provide the continuation of the radio interface from the BTS to the MFS.For this purpose, the radio and GCH interfaces have to be synchronised.A L1GCH channel has a transmission rate of 16 kbit/s (320 bits frames, every 20 ms)The following figure shows the ideal alignment between the MFS and the BTS, in terms of bufferdelay in the BTS.

B 0 B 1 B 2 B 3 B 4 B 5 B 6 B 7 B 8 B 9 B 10 B 11

T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T0

FN0

FN51

52 multiframe

DownlinkGPRSframes(idealalignment)

FN12

FN25

FN38

B 1 B 2 B 3 B 4 B 5 B 6 B 7 B 8 B 9 B 10 B 11 B 0

Figure 37 Downlink synchronisation between GCH and radio l ayers

GCH layer has the following functionalities:- GCH link establishment and synchronisation with the radio interface(MAC layer, in the MFS has to know, for multiplexing purpose, on which 52-multiframe block,a GCH frame will be sent)- RLC/MAC PDUs transfer


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 49/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5.5 RRM/RLC/MAC Layers

The MAC function defines the procedures that enable multiple MSs to share a common transmissionmedium, which may consist of several physical channels (PDCHs).The MAC function provides arbitration between multiple MSs attempting to transmit simultaneously.

The RLC function defines the procedures for a bit-map selective retransmission of unsuccessfullydelivered RLC data blocks and for segmentation and re-assembly of LLC PDUs.

The RRM function provides services for packet connection management, for radio resourcemanagement, for paging requests over radio interface.

5.5.1 Definitions

5.5.1.1 Temporary Block Flow (TBF)

A TBF is a physical connection used by 2 RR entities (one in the MS, the other in the MFS, bothinvolved in a point to point dialogue for packet connection establishment) to support theunidi rect ional transfer of LLC PDUs on packet data physical channels.The TBF is allocated radio resource on one or more PDCHs and comprises a number of RLC/MACblocks carrying one or more LLC PDUs.A TBF is temporary and is maintained only for the duration of the data transfer.

An example is given, in the figure below.MS2 and MS3 are involved in a DL transfer, using the same PDCH (PDCH3), MS4 in an UL transfer,using 2 PDCHs (PDCH3 and PDCH4) and MS1 in an UL and DL transfer, using one PDCH UL(PDCH1) and 2 PDCHs DL (PDCH1 and PDCH2).

PDCH4

PDCH3

PDCH2PDCH1

MS4MS3MS2MS1

UL TBF

DL TBF

PDCH

MS

downlink flow

uplink flow

GP

RS

telecompresentation

ED

02released

MC

D256_02.D

OC

30/09/19993B

K11202

0256D

SZ

ZA

50/122

All rights reserved. Passing on and copying of thisdocument, use and communication of its contents

not permitted without written authorization from Alcatel

Figure

38A

ddressing

concepts,ina

cell


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 51/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5.5.1.2 Temporary Flow Identity (TFI)

Each TBF is assigned a TFI, by the MFS. The TFI is unique in each direction, within a cell, but thesame TFI value may be used concurrently for TBFs in opposite directions.(32 values , per cell, for each direction: DL and UL)

5.5.1.3 Temporary Logical Link Identity (TLLI)

In the “STANDBY” or in the “READY” state (see 3), a TLLI is allocated, by the SGSN, to the MS.The TLLI identifies a link between a MS and the SGSN.

5.5.1.4 RR modes

The RR modes related to a GPRS subscriber are the following:

- packet idle modeIn this mode, the MS is not allocated any radio resource on a PDCH, it listens to the PBCCHand PCCCH or, if those are not provided by the network, to the BCCH and the CCCH.

- packet transfer modeIn this mode, the MS is allocated radio resource on one or more PDCHs for the transfer ofLLC PDUs.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 52/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 5.5.2 RRM functions

5.5.2.1 TBF establishment

The establishment of a Temporary Block Flow can be initiated by either the MS or the network.The request for the establishment of a TBF is performed

- on the PCCCH, if it exists- if not, on the CCCH

5.5.2.1.1 Uplink TBF establishment

5.5.2.1.1.1 TBF establishment initiated by the MS on PCCCH

The purpose of MS initiated TBF establishment is to establish a TBF to support the transfer of LLCPDUs in the direction from the MS to the network (uplink).Packet access shall be done on PCCCH

The PACKET CHANNEL REQUEST message is sent on PRACH and contains the followingparameters, according to the packet channel access:

packet channel access multi-slot class number ofblocks

[priority](only in 11 bitsformat)

random value(8bits/11bitsformat)

one phase access class X 1 to 4 2b/3bshort access X 1 to 8 1 to 4 3b/3btwo phase access X X 1 to 4 3b/3bpage response X X X 3b/5bcell update X X X 3b/5bMM procedure X X X 3b/5bmeasurement report(not in step1)

X X X 3b/5b

X: the field is not used [...]: conditional 2b/3b: 2 or 3 bitsaccording to theburst format

Figure 39 PACKET CHANNEL REQUEST p arameters

Priority field exists only in 11 bits format, the 8 bits format has a default priority: ‘4’ the lowest.Short access shall be used if the amount of data can fit in 8 or less than 8 RLC/MAC blocks.

5.5.2.1.1.1.1 One phase packet access

On receipt of the PACKET CHANNEL REQUEST, radio resources are allocated and a PACKET ULASSIGNMENT message is returned to the MS with the following parameters:

- allocation type (dynamic allocation)- resource allocation (PDCH(s))- coding scheme to apply- TFI- USF(s) (one for each PDCH)- packet timing advance (initial value and timing advance index)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 53/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

- packet request referenceThis field provides the information field sent in the PACKET CHANNEL REQUEST and theframe number (modulo 42432), in which the PACKET CHANNEL REQUEST was received.The purpose of this field is to address the MS and to solve possible contention situations.

The MS is requested to send a Packet Control Acknowledgement. Allocation of radio blocks, to theTBF, will start only on Packet Control Acknowledgement reception.

If radio resources are not available, the MFS sends a PACKET ACCESS REJECT to the MS, on thesame PCCCH on which the Packet Channel request message was received.

To solve the case where 2 MSs would have sent a PACKET CHANNEL REQUEST with the sameinformation field, on the same frame number, the MS shall send its TLLI in the first 3 RLC datablocks.The MFS acknowledges, with PACKET UL ACK/NACK, the first correctly received RLC data block.This message contains the TLLI which should solve the contention (the discarded MS will receive aPACKET UL ACK/NACK with the right TFI, but with another TLLI)

packet UL assignment(packet req., ref., TFI,USF,TA, TAI) (polling) (*)

packet UL ACK/NACK (TLLI, TFI)

(PRACH)

packet channelreq. (+ TA)

MS BTS MFS

Packet channel request

timingadvance

calculation

resourceallocation

LLC PDU (TLLI, TFI)LLC PDU (TLLI, TFI)

contentionresolution

Packet Control Ack.Packet Control Ack.

radio blocksallocationactivation

idle

ack.1phwaiting

assigning

transfering

switch onassignedPDCH(s)

Note: For state definition (idle, ack.1ph waiting,....) see Erreur! Source du renvoi introuvable.

(*): On the same PCCCH on which the Packet Channel request was received

Figure 40 one phase access, UL TBF esta blishment, nominal case, on PCCCH


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 54/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5.5.2.1.1.1.2 Two phases packet access

A 2 phases access can be initiated by the MS, in the PACKET CHANNEL REQUEST, provided thenetwork sets the response indicator parameter in the PACKET UL ASSIGNMENT.On receipt of the Packet Channel request, a Packet UL assignment message is sent to the MSproviding the definition of one UL radio block to send the Packet Resource request message(assigned PDCH, starting time identifying the first number of the single block), the initial TA valueand the “response indicator” denoting 2 phase access.The message is sent on the same PCCCH on which the network has received the Packet Channelrequest (no TFI, nor USF, nor TAI are yet assigned to the MS), (no polling).At occurrence of the allocated UL radio block, the MS will transmit a PACKET RESOURCEREQUEST message with the following parameters:

- TLLI (to allow contention resolution)- MS classmark- channel request description

- time-slot requested (1 to 8)- priority (1 to 4)- RLC mode (acknowledged/unacknowledged)- LLC frame type

(type of the first LLC frame to be transmitted over the requested UL TBF:- SACK or NACK- or other)

- number of RLC data octets the MS wishes to transfer- CS requested- allocation reference

This field allows the MS to associate messages sent on UL containing resource requestswith the corresponding DL resource allocation messages.

On receipt of a PACKET RESOURCE REQUEST message, MFS assigns a TFI, radio resources (onone or more PDCHs, with the associated USF(s)) and TAI, with a PACKET UL ASSIGNMENTmessage sent on PAGCH, containing the TLLI for contention resolution.The MS is requested to send a Packet Control Acknowledgement. Allocation of radio blocks, to theTBF, will start only on Packet Control Acknowledgement reception.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 55/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

Packet resource request(TLLI) (on the block affectedby TBF starting-time)

packet UL assignment (TLLI, TFI,USF(s), TAI) (polling)

packet channelreq. + TA

packet UL assignment(packet req. ref.,starting-time, TA)

(PRACH)

MS BTS MFS

Packet channel request

timingadvancecalculation

one UL blockallocation

idle

idle

Packet Control Ack.

(PAGCH)

resourceallocation

contentionresolution


ack.2phwaiting

transfering

switch onassignedPDCH


Figure 41 two phase access, UL TBF esta blishment, nominal case, on PCCCH


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 56/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5.5.2.1.1.2 TBF establishment initiated by the MS on CCCH

In this case, the RACH is used.MFS receives the request on GSL interface and the channel assignment is returned through thesame interface.The channel request message contains one of the 2 following indications:

- one phase access with request for single timeslot UL transmission. One PDCH is needed(the MS mulit-slot class is unknown in this case).In this case the immediate assignment message contains the TFI, the USF value, the TAI

and the initial timing advance value. It is sent on the same CCCH on which the Channel requestmessage was received.Then, the MFS waits for T_ul_assign_ccch, before sending a Packet UL assignmentmessage, assigning the same resources as those assigned previously, with polling indication,to request the MS a Packet Control Ack.

(RACH)

packet UL ACK/NACK (TLLI, TFI)

immediate assignment(TFI, USF, TAI, TA)

Packet UL assignment(polling). (TFI, USF, TAI)

resourceallocation

(PACCH)

Packet control ACK

(AGCH)timer(T_ul_assign_ccch)

wait

assigning

transfering

channel req. + TA

MS BTS MFSBSC

idle


ack.1phwaiting


LLC PDU (TLLI, TFI)

switch onassignedPDCH


Figure 42 one phase access, UL TBF esta blishment, nominal case, on CCCH


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 57/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

- single block packet access, one block period on a PDCH is needed for 2 phases access.In this case, the immediate assignment message doesn’t contain a TFI, nor an USF, nor aTAI, it contains only a TBF starting time indicating a block to send a RLC/MAC block (e.g. aPacket Resource request for 2 phases access) and an initial timing advance value.

(PACCH)

Packet control ACK

(RACH)

Packet UL assignment(polling). (TFI, USF(s),TAI)

Packet resource req. (TLLI)

immediate assignment(TBF starting time, TA)

(AGCH)

channel req. + TA

MS BTS MFSBSC

idle


(PACCH)

transfering

ack.2phwaiting


idle

(on the block allocatedby TBF starting time)

resourceallocation



Figure 43 two phase access, UL TBF esta blishment, nominal case, on CCCH

5.5.2.1.1.3 TBF establishment initiated by the MS during a downlink data block transfer

The MS may request establishment of an UL transfer during a DL TBF by including a channelrequest description information in the PACKET DL ACK/NACK message (time-slots requested,priority, RLC mode, LLC frame type, octets of RLC data)UL resources are allocated to the MS by returning a PACKET UL ASSIGNMENT message onPACCH, containing USF value(s) and UL TAI (different from DL TAI).


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 58/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5.5.2.1.2 Downlink TBF establishment

5.5.2.1.2.1 TBF establishment initiated by the network on PCCCH

The purpose of network initiated TBF establishment is to establish a TBF to support the transfer ofLLC PDUs in the direction from the network to the MS (downlink).The procedure is triggered, in the MFS, when receiving a LLC PDU to a MS not already having anyDL assigned radio resources (paging has been performed previously, by SGSN, but no context iskept in the MFS).The allocated radio resource (may be assigned on one or more PDCHs) is assigned to the MS in aPACKET DL ASSIGNMENT message, sent on PCCCH (or PACCH, if an UL TBF is alreadyestablished for this MS).As timing advance value is not provided in the PACKET DL ASSIGNMENT message, the poll bit isset to receive from the MS a PACKET CONTROL ACKNOWLEDGEMENT as four access bursts,(the CONTROL_ACK_TYPE parameter in the SYSTEM INFORMATION indicates acknowledgementin access bursts).On PACKET CONTROL ACK, the timing advance is calculated and forwarded to the MS with anTIMING ADVANCE/POWER CONTROL message.

Packet DL assignment(polling) (TFI, TAI)

Timing advance/power control(TFI) (PACCH)

MS BTS MFS

resourceallocation

RLC/MAC PDU (TFI)

LLC PDU

(PACCH)

(PPCH)

Packet control ACK


idle

assigning

transfering


Note: For state definition (idle, assigning,....) see Erreur! Source du renvoi introuvable.

Figure 44 DL TBF establishment, nominal case, on PCCCH


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 59/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5.5.2.1.2.2 TBF establishment initiated by the network on CCCH

In this case, a channel assignment message is sent on CCCH, through GSL interface, to assign thePACCH slot.Then a packet DL assignment, with a polling indication, is forwarded via GCH interface to ask for aPACKET CONTROL ACKNOWLEDGEMENT, in order to calculate the timing adavance.This second assignment is also necessary since it is impossible to assign a multi-slot TBF on CCCHchannel.

(PACCH)

Packet DL assignment (polling). (TFI, TAI)

channel assignment(TFI, TAI)

timer(T_dl_assign_ccch)

resourceallocation

LLC PDU

(PACCH)

Packet control ACK

timingadvance

calculation

(PCH)

MS BTS MFSBSC

Timing advance/power control (TFI)

idle

wait

assigning

transfering

switch onassigned PDCH

Note: For state definition (idle, assigning,....) see Erreur! Source du renvoi introuvable.

Figure 45 DL TBF establishment, nominal case, on CCCH

5.5.2.1.2.3 TBF establishment initiated by the network during an uplink data block transfer

During UL transfer, the MFS may initiate a DL TBF by sending a PACKET DL ASSIGNMENTmessage to the MS on the PACCH.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 60/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5.5.2.1.3 Radio resource allocation

The different cases of radio resource allocation are shown in the following table:

Radio resource allocation Corres ponding case1 UL radio block, without TAI nor USF Packet Channel request (2 phase access on

CCCH or PCCCH)This radio block will be used by the MS to send aPacket Resource request

Multiple UL radio blocks with TAI and USF - UL 1 phase access on CCCH or PCCCH- UL access during a DL transfer- Packet Resource request handling (2 phaseaccess)

Multiple DL radio blocks with TAI DL transfer


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 61/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5.5.2.2 Packet radio resource a llocation

The maximum number of PDCHs granted to a MS depends on its multi-slot class.A mobile class determines the multislot configuration which can be used by the MS.The MS constraints are the following:

- MS type (whether the MS is able to transmit and receive simultaneously)- type1: simplex MS- type2: duplex MS

- maximum number of receive timeslots per TDMA frame.- maximum number of transmit timeslots per TDMA frame.- maximum number of transmit and receive timeslots per TDMA frame- minimum time (in timeslots) between the different windows (receive, transmit,

measurement windows)

All MS classes are supported with the following limitations, in B6.2:- type1 MS are limited to 2 UL slots and 4 DL slots- type 2 MS are limited to 5+5 configuration- allocations with hole between slots of the same direction are not supported

Furthermore, an O&M parameter (MAX_PDCH_PER_TBF) may limit the number of PDCHsallocated to a TBF.

With dynamic allocation (USF), an UL transfer requires symetric capabilities (the MS has to listen allthe allocated PDCHs for USF reading).That means that simplex MS may only be granted a configuration of class 1 (1 DL TS + 1 UL TS) orclass 5 ( 2 DL TS + 2 UL TS) (see the figure below)

Rx Mx

0 1 2 3 4 5 6 7

DL

TxUL

0 1 2 3 4 5 6 7

Ttb Tra

Rx

Tx

- Rx: DL slot- Tx: UL slot- Ttb: minimum number of slots between the end of the last previous transmit or receive slot andthe first next transmit- Tra: minimum number of slots between the previous transmit or receive slot and the next receive

slot when measurement (Mx) is to be performed between

(These values are defined in GSM 05.02, annex B, for each multi-slot class)(for more details, see also [14])

Figure 46 class 5, symetric conf iguration


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 62/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

A DL transfer doesn’t require symetric capabilities.One slot is used on UL path to carry the PACCH of the DL TBF (DL RLC data blocks carrying apolling request shall be sent over the PACCH slot).

The allocation strategy consists to maximise the usage of the allocated PDCHs and, if necessary, torequire additional PDCH(s) to the BSC.

5.5.2.3 Allocation on PDCH

The maximum number of TBFs per PDCH is limited by the following parameters:- 16 TAI values are available per PDCH- 6 USF values are available for UL traffic on GPRS master PDCH- 7 USF values are available for UL traffic on GPRS non-master PDCH- 32 TBF per cell

O&M parameters define thresholds used to invoke allocation of new PDCH:- An O&M constant defines the max. number of TBFs per PDCH (N_TBF_PER_PDCH)- An O&M constant defines the max. number of TBFs per MPDCH (N_TBF_PER_MASTER)

5.5.2.4 Cell handling

Cell availability for GPRS traffic depends on the following indications:- BSC indications- administrative state- GCH availability- Gb interface state

5.5.2.5 PDCH release

When a cell becomes unavailable for GPRS traffic (e.g. following either an O&M command or a Gbfailure), PDCH release messages are sent to all the MSs of the cell which are involved in a datatransfer, before releasing the PDCH.On reception, the MS shall immediately stop transmitting.

5.5.2.6 QoS

5.5.2.6.1 Radio QoS

The radio QoS is the QoS granted on the radio interface to transfer LLC PDUs.The radio QoS is defined by the following parameters:

- throughput- service precedence- RLC reliability mode- BSS transfer delay

5.5.2.6.2 Throughput

Throughput indication is given:- DL, in the “requested throughput” field of DL BSSGP PDUs- UL, in the “peak-throughput-class” field of the Packet Resource request message (i.e. thisinformation is known by the network only in a 2 phase access)

In B6.2, the throughput information is only taken into account, UL, for NS load-sharing.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 63/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

A MS is granted as many PDCHs, as supported by its multislot class, furthermore O&M data definesthe maximum number of PDCHs allocated to a TBF.The PDCH throughput is equally shared between all MSs to which this PDCH has been allocated.

The multislot class information is given:- DL, in DL BSSGP PDUs- UL, only in the following cases:

- Packet Resource request, on PACCH- One phase access, on PRACH- TBF establishment requested through Packet DL ACK/NACK

(in the other cases, the MS is considered as a monoslot MS)

5.5.2.6.3 Service precedence

Precedence indication is given:- DL, in the “precedence” field of DL BSSGP PDUs- UL, in the “priority” field of the Packet Channel request message (1/2 phase access, shortaccess, 11 bits format only)

This information is not taken into account, in step1, neither for TBF establishment nor for TBF pre-emption.This information is only used by the persistence level.

5.5.2.6.4 RLC reliability mode

RLC offers 2 transmission modes:- acknowledged mode- unacknowledged mode

RLC mode indication is given:- DL, in DL BSSGP PDUs- UL, in the Packet Resource request message (2 phase access)When the indication cannot be given, the following rules are applied:

- 1 phase access: acknowledged mode- single block access (for 2 phase access): unacknowledged mode- short access: acknowledged mode- Page response/cell update/MM procedure: acknowledged mode

5.5.2.6.5 BSS transfer delay

BSS transfer delay information, is given, DL, through “PDU life time”, provided by DL BSSGP PDUs.

When PDU life time expires, the LLC PDU is deleted.In case of DL TBF unavailability, requests are queued and served according to their PDU life time.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 64/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 5.5.3 RLC functions

5.5.3.1 Acknowledged mode op eration

The transfer of RLC data blocks in the RLC acknowledged mode uses retransmissions of RLC datablocks.The transmitting side numbers the RLC data blocks via the Block Sequence Number (BSN) forretransmission and reassembly.The receiving side sends PACKET UPLINK ACK/NACK or PACKET DOWNLINK ACK/NACKmessages in order to request retransmission of RLC data blocks.

5.5.3.2 Unacknowledged mode op eration

The transfer of RLC data blocks in the RLC unacknowledged mode does not include anyretransmissions.The BSN is used to number the blocks for reassembly.The receiving side sends PACKET ACK/NACK messages in order to convey the necessary othercontrol signalling messages while the fields for requesting retransmission are not used.

5.5.3.3 Segmentation of LLC-PDUs into RLC data blocks

Each received LLC PDU shall be segmented into RLC data blocks.If the contents of an LLC PDU do not fill an integer number of RLC data blocks, the beginning of thenext LLC PDU shall be placed within the final RLC data block of the first LLC PDU with no paddingbetween the end of the first LLC PDU and the beginning of the next.If the final LLC PDU in the TBF does not fill an integer number of RLC data blocks, filler octets shallbe used to fill the remainder of the RLC data block.

5.5.3.4 Re-assembly of LLC PDUs from RLC data blocks

RLC data blocks shall be collected at the receiver until all RLC data blocks comprising an LLC PDUhave been received.During RLC acknowledged mode operation, received LLC PDUs shall be delivered to the higherlayer in the order in which they were originally transmitted.During RLC unacknowledged mode operation, received LLC PDUs shall be delivered to the higherlayer in the order they are received.

5.5.3.5 Uplink TBF rel ease

In this direction, only MS initiated release is implemented.The MS initiates the release of the TBF by beginning the countdown process ( a countdown value issent in each RLC data block to indicate to the MFS the absolute Block Sequence Number of the lastRLC data block).

5.5.3.6 Downlink TBF rel ease

The release can be triggered either by the MFS or the MS.

5.5.3.6.1 MFS initiated release

The MFS initiates the release of a DL TBF by sending an RLC data block with the Final Bit Indicator(FBI) set.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 65/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

5.5.3.6.2 MS initiated release

The MS can initiate a DL TBF release by setting the TBF_release_bit in the Packet DL ACK/NACKmessage and in all subsequent Packet DL ACK/NACK message, until the TBF is released.

5.5.4 MAC functions

5.5.4.1 PDCH multiplexing

Each PDCH is a shared medium between multiple MSs and the network.It consists of asymmetric and independent uplink an downlink channels.

5.5.4.1.1 Downlink

The DL, from the MFS to multiple MSs, does not require contention arbitration.Different logical channels share the same PDCH:

- PBCCHIt is mapped on 1 to 4 blocks (B0, B6, B3, B9).The number of blocks (BS_PBCCH_BLKS) is broadcast on PBCCH in B0, which always exists, incase of GPRS master channel.

- PDTCH and PACCHThe scheduling is based on the use of the TFI to address individually all the MSs engaged in a trafficexchange.Each MS monitors its assigned PDCHs and filters out the received blocks based on the TFI, which iscontained in the RLC header.

- PCCCH (PAGCH, PPCH)The PCCCH, PDTCH and PACCH can be mapped dynamically, by the MFS and are identified by themessage header.The configuration is partly fixed by some parameters broadcast by the PBCCH:- BS_PBCCH_BLKS: number of PBCCH blocks- BS_PAG_BLKS_RES: number of blocks not used for PBCCH or PPCH.

It corresponds to the number of blocks for PAGCH, PDTCH and PACCH.

The MS shall attempt to decode every DL RLC/MAC block on all assigned PDCHs.Whenever the MS receives an RLC/MAC block containing an RLC control block, the MS shall

attempt to interpret the message therein. If the message addresses the MS (the identity of the MS isa specific field of the control message according to its type, e.g “UL TFI” in Packet UL ACK/NACK) ,the MS shall act on the message.

5.5.4.1.2 Uplink

The UL is shared among multiple MSs and requires contention control procedures.Multiplexing is handled by dynamic allocation medium access mode, in GPRS step1.The medium access mode the MS is to use is signalled in the Packet UL Assignment.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 66/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

Different logical channels share the same PDCH:

- PDTCH/PACCH related to one MS handling an UL packet transfer

The allocation mechanism is based on a token (USF: Uplink Status Flag) distributed by the MFS,allowing the sharing of the UL resource between different MSs which are involved in UL packettransfer, on the same PDCH.All these MSs having received one USF value in the Packet UL Assignment, listen to the USF sent,by the MFS, in all DL blocks. When the decoded USF, in DL block Bn, matches the USF allocated tothe MS, by the MFS, the MS gets the right to transmit one RLC/MAC block in UL block Bn+1.

- PRACH used by MSs for packet access request

A MS which wants to initiate a packet access procedure, has to send a Packet Channel Request, onPRACH.With this aim, the MS has to listen DL PDCH to denote a specific USF value (FREE) denotingPRACH.A FREE USF value in a DL block Bn, means that UL block Bn+1 is a PRACH.

- PACCH related to one MS handling DL packet transfer

Another value (no emission) is used to authorize one MS, without USF, to transfer in the UL direction(e.g. MS involved in a DL packet transfer)A MS involved in a DL packet transfer shall attempt to decode every DL RLC/MAC block on theassigned PDCH, carrying the PACCH.Whenever a MS receives a RLC data block addressed to itself and with a valid RRBP field(scheduling an UL block) in the MAC data block header, the MS shall transmit a Packet DLACK/NACK. (except at the end of a DL transfer, in unacknowledged mode!!)Whenever a MS receives a RLC control block addressed to itself and with a valid RRBP field in theMAC data block header, the MS shall transmit a Packet Control ACK.The RRBP field contained in DL block Bn specifies a single UL block in which the MS shall transmit.The UL block can be either Bn+2, Bn+3, Bn+4 or Bn+5.Consistency between USF and RRBP indications shall be ensured.

In Figure 47, an example is detailed.

USF= no emission+ RRBP

allocationindications

uplink PDCH

PDTCHi

PACCHi

PDTCHj

PACCHj

PRACH

PACCHk

USFi

USFj

USF=FREE

Figure 47 Logical channels on uplink PDCH and multiplexing indications

- PACCHk is related to a MS involved in a DL packet transfer- USFi is allocated to MSi, for UL packet transfer- USFj is allocated to MSj, for UL packet transfer


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 67/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

The following table shows an example of UL scheduling:- DL Bn has its USF equal to USFi, that means MSi transfer will be allowed in UL Bn+1.- DL Bn+1 has its USF equal to USFj, that means MSj transfer will be allowed in UL Bn+2.Furthermore, this DL block is addressed to MSk and the RRBP indication is set (+3), whichmeans that MSk has to send a Packet DL ACK/NACK in UL Bn+4 (Bn+1 + 3)- DL Bn+2 has its USF equal to “FREE”. It means that UL Bn+3 is a PRACH.- DL Bn+3 has its USF equal to “no emission”. It means that UL Bn+4 has already beenscheduled by the RRBP mechanism.

downlink uplinkblock number USF RRBP

Bn USFi falseBn+1 USFj +3 MSiBn+2 FREE false MSjBn+3 no emission false PRACHBn+4 USFi false PACCHkBn+5 USFj false MSiBn+6 MSj

Note: During the establishment of an UL TBF, on CCCH, with 2 phase access, another mechanismis used (see Figure 43). One block (Bx) is assigned, thanks to the “TBF starting time” parameter ofthe immediate assignment message.DL Bx-1 block shall have its USF value equal to “no emission”.

5.5.4.2 Polling mechanism

This mechanism is used by the MFS to request a response from the MS.It is based on the RRBP mechanism which allocates a block for this response.It is used for different purposes:

- to require a Packet Control ACK either to measure initial timing advance or to acknowledgea control message.

Particularly, the MS will be requested to send a Packet Control Acknowledgement uponreceipt of any Packet Assignment, in order to allocate radio blocks, to this TBF, only when

the acknowledgement is received, to optimize the radio resources usage.- to require blocks acknowledgement in DL transfer, in acknowledged mode- to allocate an UL PACCH block, during DL transfer in unacknowledged mode.

The different cases are summarized in the following table:

DL message received by theMS

UL message forwarded bythe MS

usage

RLC/MAC control block Packet control ACK - initial timing advance measure- or message controlacknowledgement

RLC/MAC data block- acknowledged mode- or unacknowledged mode(FBI=0)

Packet DL ACK/NACK - DL transfer acknowledgement- or UL PACCH block allocation

RLC/MAC data block- unacknowledged mode(FBI=1)

Packet control ACK - end of unacknowledgedtransfer

FBI: Final Block Indicator (“=1”: last block of the transfer)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 68/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

6. GB INTERFACE

The Gb interface connects the BSS and the SGSN, allowing the exchange of signalling informationand user data.GPRS signalling and user data are sent in the same transmission plane.

Gbinterface

FRnetwork

MFS

NS (SNS)

NS (NSC)

BSSGP

L1

SGSN

NS (SNS)

NS (NSC)

BSSGP

L1

Figure 48 Gb interface

6.1 Protocol layers

6.1.1 Link layer

The Gb interface link layer is based on Frame Relay (FR). Frame relay virtual circuits areestablished between SGSN and BSS. LLC PDUs from many users are multiplexed on these virtualcircuits.The virtual circuits may be multi-hop and traverse a network of frame relay switching nodes.Frame relay core functions are implemented (DL-CORE protocol defined in Q922, Annex A) enablingthe sending/reception of frame relay unacknowledged frames.

6.1.2 Network Service layer

see [4]

The NS entity is composed of 2 sub-layers:- the NSC (Network Service Control), independent from the intermediate transmission

network used on the Gb interfaceIt is responsible for the following functions:

- NS PDU transfer between BSS and SGSN(PDU order is kept, except under exceptional circumstances)- load-sharing- NS-VC management

- the SNS (Sub-Network Service), dependent on the intermediate transmission networkIt provides access to the intermediate network.Failure detections are reported to NSC.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 69/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

In this phase of GPRS, the intermediate transmission network is Frame Relay (FR). Only FRPermanent Virtual Connections are used, which are statically configured by O&M.Point to point SGSN-MFS connections constitute a particular case of simplified transmissionnetwork.Unacknowledged mode is used between the MFS and the SGSN.

6.1.3 BSSGP layer

(see [5])

The primary function of BSSGP is to convey LLC PDUs and GPRS MM signalling.In the BSS, it acts as an interface between LLC frames and RLC/MAC blocks.In the SGSN, it forms an interface between RLC/MAC-derived information and LLC frames.The main functions for the BSSGP protocol are to:

- provide a connectionless link between the SGSN and the MFS- transfer data unconfirmed between the SGSN and the MFS- provide tools for DL data flow control between the SGSN and the MFS- handle paging requests from the SGSN to the MFS- give support for flushing of old messages in the MFS (e. g. when an MS changes BSS)

6.2 Addressing

(see Figure 49 and Figure 50)

6.2.1 Permanent Virtual Channel (PVC)

A Frame Relay PVC allows the service of multiplexing on a Bearer Channel.Each PVC is associated with one NS-VC.At MFS, a PVC is identified by its Data Link Connection Identifier (DLCI), which is independent of theone defined at SGSN side.There is a dedicated DLCI (DLCI=0) used by the FR to support signalling functions (it is not a PVC).

6.2.2 Bearer Channel (BC)

A BC is a nx64 kbit/s channel on a 2048 kbit/s link and supports a set of PVCs.

6.2.3 Network Service Virtual Connection (NS-VC)

In order to provide end-to-end communication between the MFS and the SGSN irrespective of theexact configuration of the Gb interface, the concept of NS-VC is used.The peer-to-peer communication between remote NSC user entities is performed over NS-VCs.NS-VCs are end-to-end virtual connections between the MFS and the SGSN.Each NS-VC is identified by means of a NSVCI having end-to-end significance across the Gbinterface.NS-VCs are statically configured by O&M.In GPRS step1, there is a one to one mapping between one NS-VC and one FR PVC.In step1, only one NS-VC (PVC) per BC.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 70/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 6.2.4 Network Service Entity (NSE)

The NSC provides a communication service to NS user peer entities (NSE).One group of NS-VCs is configured between 2 peer NSEs, by administrative means.The Network Service Entity Identifier (NSEI) is an end-to-end identifier and shall be unique within aSGSN.At each side of the Gb interface, there is a one-to-one correspondence between a group of NS-VCsand a NSEI.

A NSE is associated to a set of BVCs.The NSE maps a set of BVCs on a set of NS-VCs.

In Alcatel implementation, a NSE is defined as the connection of one BSS to one GPU.(in step1: one NSE corresponds to one BSS).

6.2.5 BSSGP Virtual Connection (BVC)

A BVC is a virtual end-to-end path between BSSGP peer entities.A BVC is identified by a BVCI which is unique in one NSE and has an end-to-end significance acrossthe Gb interface.there are two types of BVCs, in B6.2:

- Point-To-Point (PTP) BVC devoted to the GPRS traffic of one cell (BVCI>1)- signalling BVC, which is the signalling circuit of all the BVC-PTPs of one NSE (BVCI=0)(BVCI = 1, is reserved for PTM: Point To Multipoint)

In the BSS, BVCIs are statically configured, by administrative means.At the SGSN side, BVCIs associated with PTP functional entities are dynamically configured, BVCIsassociated with signalling functional entities are statically configured.

The BVCI together with the NSEI uniquely identifies a BVC within a SGSN.The BVCI and NSEI are used on the NS-SAP for layer-to-layer communication.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 71/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

BSSGP

PVC

Bearer channel

NSC

SNS

BVC

cells

NSE

BVCI0, used for signalling

NS-VC

NSE

BSS

RRM

Figure 49 Add ressing concepts in the MFS

Note: Only one NS-VC per bearer channel, in step1


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 72/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

BVCI=3Cell id8

At MFS: Cells andBVC-PTPs related toBSC#1 SGSN

BVCI=2NSVCI=1DLCI=16

BVCI=2

NSVCI=2DLCI=23

Cell id2

BVCI=4Cell id3

BVCI=5Cell id9

BVCI=6Cell id7

BVCI=3

BVCI=4

BVCI=5

BVCI=6

NSVCI=1DLCI=98

BearerChannel=3Bearer

Channel=1

FrameRelaynetwork

BearerChannel=2

NSVCI=3DLCI=34

NSVCI=2DLCI=23

NSVCI=3DLCI=17

NSEI=1Load sharing

Figure 50 Add ressing concepts on Gb interface

Note: Only one NS-VC per bearer channel, in step1


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 73/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

6.3 NS functionalities

(see [4])

6.3.1 Load sharing function

The load sharing function distributes the NS-PDU traffic among the unblocked NS-VCs of the sameNSE.The NS-VC selection is based on the LSP value.At one side of the Gb interface, all BSSGP UNITDATA PDUs related to an MS shall be passed withthe same LSP, to the underlying network service.The LSPs used at the MFS and SGSN for the same MS may be set to different values.Thus, the load sharing function guarantees that for each BVC, the order of all NS-PDUs marked withthe same LSP value is preserved.

At the data transfer establishment (see Figure 51), the BSSGP layer sends a NS-UNITDATA-reqprimitive to the NS layer with the following information:

- NSEI- BVCI- LSP (Link Selector Parameter)- bit rate

A set of NS-VCs is associated to each NSEI.Among these NS-VCs, one is chosen which is able to provide the requested bit rate.The following relationship is established: NSEI, BVCI, LSP --> NS-VC.All the following NS-UNITDATA-req with the same NSEI, BVCI,LSP identification will use the sameNS-VC.The previous relationship is withdrawn, at the end of the data transfer, on TRN-STOP-req primitivereception, from the upper layer (see Figure 52).

GP

RS

telecompresentation

ED

02released

MC

D256_02.D

OC

30/09/19993B

K11202

0256D

SZ

ZA

74/122



Procedure

load_sharing1(2)

routingproce

duretrigg

eredo

nN

S-U

NIT

DA

TA

-req

reception

(NS

EIa

,BV

CIb,L

SP

c,bit

rate)

access

torouting

table

(BV

CIb,L

SP

c)

(BV

CIb,

LSP

c)?D

oes

theiden

tificatio

n(N

SE

Ia,B

VC

Ib,LS

Pc)

existsin

therou

ting

table?

access

toth

eN

SE

IaN

S-V

Cs

list

alist

ofNS

-VC

sis

associa

tedto

NS

EIa

NS

-VC

choice

accordingto

thereq

uested

bit

rate

registrationin

the

routingta

ble

relatio

nshipN

SE

Ia,BV

CIb

,LSP

c-->

NS

-VC

isreg

istered

inth

erouting

table

routingN

SP

DU

isro

utedon

theN

S-V

Cgiven

by

therou

ting

table

N

Y

Figure

51N

Srouting

(routingrelationship

creation)

GP

RS

telecompresentation

ED

02released

MC

D256_02.D

OC

30/09/19993B

K11202

0256D

SZ

ZA

75/122



Procedure

load_sharing2(2)

end

of

transfertrigg

eredo

nT

RN

-ST

OP

-reqrece

ption(N

SE

Ix,BV

CIy,L

SP

z)

access

torouting

table

(BV

CIy,

LSP

z)

suppressio

nin

the

routingta

ble

relatio

nshipN

SE

Ix,B

VC

Iy,LS

Pz

-->N

S-V

Cis

withdraw

nfrom

thero

utingtable

Figure

52N

Srouting

(rotingrelationship

deletion)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 76/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 6.3.2 NS-VC management function

6.3.2.1 Blocking/Unblocking of an NS-VC

When a NS-VC becomes locally unavailable either at the MFS or at the SGSN, the remote NS entityshall be informed by means of a blocking procedure.A NS-VC may be blocked, because of:

- O&M command (administrative state = locked)- equipment failure (operational state = disabled)- test procedure failure (operational state = disabled)

When a NS-VC becomes available again, the NS entity which initiated the blocking procedure (or thereset procedure) informs the remote NS entity by means of an unblocking procedure.

NS-BLOCK-ACK

NS-BLOCK

NSentity

NSentity

Note: These PDUs are sent on any “enabled” NS-VC belonging to the same NSE

Figure 53 NS-VC Blocking procedure

NS-UNBLOCK-ACK

NS-UNBLOCK

NSentity

NSentity

Note: These PDUs are sent on any “enabled” NS-VC belonging to the same NSE

Figure 54 NS-VC Unblocking procedure


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 77/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

6.3.2.2 Reset procedure

The reset procedure is used when a new NS-VC is set-up, after processor restart, after failurerecovery, or when its state is undetermined.Upon completion of the reset procedure, the NS-VC is “blocked” and its operational state is“enabled”.

NS-RESET-ACK

NS-RESET

NSentity

NSentity

Note: These PDUs are sent on the NS-VC being reset

Figure 55 NS-VC Reset procedure

6.3.2.3 NS-VC Test procedure

This procedure is used to check that end-to-end communication exists between peer NS entities, ona given NS-VC.This procedure is initialised upon successful completion of the reset procedure and shall be thenperiodically repeated.When the procedure is successful, the operational state is “enabled” otherwise it is “disabled” and theNS-VC becomes “blocked”.

NS-ALIVE-ACK

NS-ALIVE

NSentity

NSentity

Note: These PDUs are sent on the NS-VC being tested


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 78/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

6.4 BSS GPRS Protocol (BSSGP) functionalities

(see [5])

The service model is the following:- “RL “ (ReLay) and “BSSGP” for functions controlling the transfer of LLC frames- “GMM” (GPRS Mobility Management) for functions associated with mobility management

between an SGSN and a BSS.- “NM” (Network Management) for functions associated with Gb interface and BSS-SGSN

node management.

BSSGP

GMM

NM

BSSGP

NS

RRM

RLC

MAC

RL

MFS

NM

BSSGP

NS

LLC GMM

SGSN

Figure 56 BSSGP service model


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 79/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 6.4.1 Data transfer procedures between RL and BSSGP SAPs

Data transfer is performed in an unacknowledged mode.There is one LLC PDU per BSSGP PDU.

UL-UNITDATA

MFSRL SAP

SGSNBSSGP SAP

DL-UNITDATA

Figure 57 data PDUs

6.4.1.1 DL UNITDATA procedure

DL UNITDATA PDUs contain PDU life-time information element which is used by theRRM/RLC/MAC function, for radio resource scheduling on the MS-network interface.

6.4.1.2 UL UNITDATA procedure

LSP (TLLI), BVCI, NSEI and QoS profile information (requested throughput) is used for load sharingat NS layer level.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 80/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 6.4.2 Signalling procedures between GMM SAPs

MFSGMM SAP

SGSNGMM SAP

PAGING-CS

PAGING-PS

RADIO-STATUS

acknowledgement

Figure 58 signalling PDUs between GMM SAPs

All these PDUs are unacknowledged.

6.4.2.1 Paging

6.4.2.1.1 CS paging

When instructed by the MSC/VLR to initiate circuit-switched transmission between the MSC and aMS, the SGSN shall send a PAGING CS PDU to the MFS. (network operation mode I)

6.4.2.1.2 PS paging

When wishing to initiate packet-switched transmission between an SGSN and MS, an SGSN shallsend a Paging PS PDU to the MFS.

6.4.2.2 Radio status procedure

The RADIO-STATUS PDU indicates bad conditions on the radio interface.This PDU has the following parameters:

- TLLI or TMSI or IMSI- radio cause (radio contact lost with the MS, radio link quality insufficient, ...)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 81/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

6.4.3 Signalling procedures between NM SAPs

MFSNM SAP

SGSNNM SAP

FLUSH-LL

LLC-DISCARDED

BVC-FLOW-CONTROL

MS-FLOW-CONTROL

BVC-BLOCK

BVC-UNBLOCK

BVC-RESET

STATUS

acknowledgement

Figure 59 Signalling PDUs between NM SAPs

6.4.3.1 FLUSH-LL procedure

The SGSN sends a FLUSH-LL to MFS to ensure that LLC-PDUs queued at a cell for an MS aredeleted.The parameters are : TLLI and BVCI.This PDU is acknowledged.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 82/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

6.4.3.2 LLC-DISCARD procedure

The MFS sends a LLC-DISCARDED PDU to SGSN, when a local LLC-PDU deletion has beenperformed (e.g. following a PDU life-time expiry)The parameters are: TLLI and number of frames discarded.

6.4.3.3 Flow control procedure

Only downlink flow control is performed (from the MFS to the SGSN)This flow control applies on the 2 following entities:

- the cell (i.e. one BVCI)by means of FLOW-CONTROL-BVC PDU which has the following parameters:

- tag (reference to be returned in the acknowledgement)- BVC throughput indication- BVC measurement (not used in B6.2)

describes average queuing delay for a BVCA FLOW-CONTROL-BVC-ACK, containing the field ‘tag’ acknowledges the previous PDU.

- the MS (i.e. TLLI)by means of FLOW-CONTROL-MS PDU which has the following parameters:

- TLLI- tag- MS throughput indication

A FLOW-CONTROL-MS-ACK, containing the field ‘tag’ acknowledges the previous PDU.

The MFS uses flow control to adjust the flow of BSSGP UNITDATA PDU to its buffers.This flow control is triggered by RRM/RLC/MAC layer (see 8.2.2.2).

BSSGP UNITDATA PDUs queued within the MFS that are not transferred across the radio interfacebefore the PDU life time expires shall be deleted and the SGSN shall be notified by a LLC-DISCARDED PDU.

6.4.3.4 BVC blocking and unblocking procedure

The BVC blocking and unblocking procedures are initiated by the MFS to remove from use, or bringinto use, a BVCThe MFS may block a BVC because of:

- O&M blocking for intervention purpose (O&M request)- equipment failure at the BSS (RRM request)- cell equipment failure at the BSS (RRM request)

To block a BVC, the MFS shall send a BVC-BLOCK PDU with BVCI and cause as parameters.This PDU has to be acknowledged (BVC-BLOCK-ACK, with BVCI as parameter).

To unblock a BVC, the MFS sends a BVC-UNBLOCK PDU with BVCI indication.This PDU has to be acknowledged with BVCI indication.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 83/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

A BVC-RESET procedure is used to synchronise BVC states between the MFS and the SGSN.This procedure may be initiated either by the MFS or the SGSN, on the following events:

- BVC creation- processor recovery- underlying network recovery- ....

After performing a BVC-RESET procedure, the affected BVC is assumed to be in the ‘unblocked’state in the SGSN. So the MFS has to initiate a block procedure if the affected BVC is marked‘blocked’ in the MFS.The BVC-RESET PDU has the following parameters:

- BVCI- cause

This PDU has to be acknowledged by a BVC-RESET-ACK PDU with the BVCI indication.

RESET

O&Mblocking

orfailure

O&Munblocking

orrecovery

unblocked

BVC-BLOCKBVC-UNBLOCK

orRESET

unblocked

RESET(1)

blockedblocked

MFS SGSN

(1): In this case, a block procedure has to be initiated

Figure 60 BVC state transitions in the MFS and SGSN

6.4.3.5 Status

When an exception condition occurs (e.g. BVCI unknown, BVCI blocked, ...) either in the MFS or theSGSN, a STATUS PDU is sent to the peer entity.This PDU has the following parameters:

-cause- PDU in error

This PDU is not acknowledged.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 84/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

7. O&M INTERFACE

7.1 Interface modelisation

Telecom layer - O&M interface is of type “manager-agent”, where The O&M is the manager and thetelecom layer the agent.This interface can be modeled through “entity” classes (by analogy with object classes).These classes can be instanciated.

An entity class is defined by:- attributes- operations which can be performed on the class

- CREATE (to create an entity instance)- DELETE (to delete an entity instance)- GET (to read attribute values)- SET (to set attribute values)- ACTION (to perform specific actions on the entity)

- behaviour- notifications may be forwarded, on certain circonstances

(e.g. state change)(Alarms are a specific type of notifications)

O&M

Telecomlayer

operations

entity

notifications

attributes

Figure 61 O&M interface modelisation


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 85/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

7.2 Managed entities, in the MFS

Note: In this paragraph, distinction between RRM, RLC and MAC is not taken into account.

In the MFS, the following entity classes are managed, by O&M:

- L2-GCH:- GCH class (only one instance to model the layer)

- BSCGP:- GSL classA GSL is one 64 kbit/s LAPD link, between BSC and MFS.

- BSCGP class (only one instance to model the layer)

- RRM:- CELL classGSM cell

- Gic_Group classA Gic_Group is a set of AterC circuits (64 Kbit/s circuits), which can be used for GPRS trafficand which are carried by the same PCM

- BSS class

- RRM class (only one instance to model the layer)

- RLC class (only one instance to model the layer)

- MAC class (only one instance to model the layer)

- BSSGP:- BVC-PTP classOne BVC-PTP represents the GPRS traffic of one cell on Gb interfaceIt is managed, by O&M, through the cell entity.

- BVC-SIG classOne BVC-SIG represents, on Gb interface, signalling related to one NSE (i.e. a couple GPU-BSS, in B6.2, one BSS is handled by only one GPU).It is managed, by O&M, through the BSS entity.

- BSSGP class (only one instance to model the layer)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 86/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

- NSC:- NSVC classTraffic of one NSE is shared between NSVCs, on Gb interface.There is a one to one mapping between NSVC and PVC.

- NSC class (only one instance to model the layer)

- SNS:- PVC classOne PVC is a frame relay Permanent Virtual Channel mapped on a bearer channel, on Gbinterface.

- BC classOne BC is a Bearer Channel on the Gb interface.

- SNS class (only one instance to model the layer)

BVC_SIG

NSVCBVC_PTP

cell

BC

PVC

1 to 1 association

1 to n association

GPU

GSL

BSS

Gic_Group

2

Figure 62 Entity relationship diagram


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 87/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 7.2.1 GSL entity

The GSL entity class is managed by BSCGP.GSL instances are created by O&M.When the 2 GSLs, towards one BSC are disabled, RRM is notified (NTM-BSC-state-change-ind)The GSL entity class has the following attributes:

- GICid (circuit identity to support the GSL)

acknowledgement

NTM-BSC-Reset-ind/req

NTM-BSC-State-ind

dl-establish-ind

dl-release-ind

dl-establich-reqdl-release-reqL2GSL

LM-GSL-create-reqLM-GSL-delete-req

BSCGP

RRM

O&M

GSL

Figure 63 BSCGP interf aces, related to GSL entity

The interface with L2GSL is used to handle the LAPD link supporting the GSL.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 88/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 7.2.2 BSS entity

The BSS entity class is managed by RRM.BSS instances are created by O&M.The BSS entity class has the following attributes:

- BSSid- network operation mode- operational state- administrative state- availabilty status

- dependency (BVC-SIG not operational)- off-line (BSCGP indication)

NTM-BSC-State-ind

NTM-BSC-Reset-ind/req

LM-BSS-State-change-ind

LM-BSS-create-reqLM-BSS-delete-reqLM-BSS-SET-req

O&M

BSS

BSCGP

RRM

NTM-BSC-State-req

BSSGP

BVC-SIG

NM-BVC-SIG-CREATE-reqNM-BVC-SIG-DELETE-req

NM-BVC-SIG-T-STATUS-ind

NM-BVC-SIG-START-reqNM-BVC-SIG-STOP-req

Figure 64 RRM interf aces, related to BSS entity

The possible state combinations are the following:

operational state availability status administrative statedisabled dependency locked/unlockeddisabled off-line locked/unlockedenabled 0 locked/unlocked


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 89/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 7.2.3 Gic group entity

The Gic group entity class is managed by RRM.Gic group instances are created by O&M.The Gic group entity class has the following attributes:

- Gic group id.- list of AterC circuits which are defined with:

- AterC id. (identification on the Ater interface, 64kbit/s time-slot within the Gic group)- Atermux id. (identification on the AterMux interface: PCM, Time-Slot, nibble)

- BSS id- operational state (read only attribute)

LM-Gic-Group-create-reqLM-Gic-Group-delete-reqLM-Gic-Group-GET-req

NTM-GICGROUP-State-req

BSCGP NTM-GICGROUP-state-ind

GICGroup

RRM LM-Gic-Group-state-change-ind

O&M

NTM-BSC-reset-ind

Figure 65 RRM interf aces, related to Gic-group entity


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 90/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 7.2.4 Cell entity

The Cell entity class is managed by RRMCell instances are created by O&M.A cell instance is associated to a BVC instance which is managed by BSSGP, so synchronisation isrequested between these 2 instances.The cell entity class has the following attributes:

- cell id- BSC id.- MIN_PDCH_Group- MAX_PDCH_Group- MAX_PDCH_HIGH_LOAD- MIN_MPDCH- MAX_MPDCH- telecom parameters- adjacent cell parameters- administrative state- operational state- availability status

LM-CELL-state-changecell

BSC(viaBSCGP)

LM-CELL-create-reqLM-CELL-delete-req

RRM BSSGP

O&M

NTM-CELL state-ind

NTM-CELL start/stop-req

NTM-CELL state-req

NM-BVC-PTP-CREATE-reqNM-BVC-PTP-DELETE-req

NM-BVC-PTP-START-reqNM-BVC-PTP-STOP-req

NM-BVC-PTP-T-STATUS-ind

NTM-CELL-Detach-req

NTM-CELL-Detach-ind

BVC-PTP

Figure 66 RRM interf aces, related to Cell entity


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 91/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

operat ional state availability status administrative state co mmentsdisabled off-line locked/unlocked BSCGP unavailability

indicationdisabled dependency locked/unlocked BVC-PTP

unavailabilitydisabled off-line + dependency locked/unlockeddisabled failed unlocked MFS internal failureenabled 0 locked/unlocked

7.2.5 BVC-PTP entity

The BVC entity class is managed by BSSGP.BVC instances are created by RRM.Its status has 2 components:

- operational/not operational- operational: a BVC-PTP RESET has been successfully performed- not operational: the BVC-PTP RESET procedure has not been performed

- started/stopped- started: RRM has requested a start of the BVC-PTP- stopped: RRM has stopped the BVC-PTP or has not yet started the

BVC-PTP

NM-BVC-PTP-START-reqNM-BVC-PTP-STOP-req

BVC-BLOCKBVC-UNBLOCK

SGSN(via NS)

RRMBSSGP

BVC-PTP

BVC-RESET

NM-BVC-PTP-CREATE-reqNM-BVC-PTP-DELETE-req

NM-BVC-PTP-T-STATUS-ind

Cell

Figure 67 BSSGP interf aces, related to BVC-PTP entity


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 92/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 7.2.6 BVC-SIG entity

The BVC-SIG entity class is managed by BSSGP.BVC-SIG instances are created by RRM.Its status has 2 components:

- operational/not operational- operational: the NSE, at NS level, is available- not operational: the NSE, at NS level, is not available

- started/stopped- started: RRM has requested a start of the BVC-SIG- stopped: RRM has stopped the BVC-SIG or has not yet started the

BVC-SIG

SGSN(via NS)

BVC-RESET

RRM

NSCBSSGP

BVC-SIG

NM-BVC-SIG-CREATE-reqNM-BVC-SIG-DELETE-req

NM-BVC-SIG-T-STATUS-ind

NM-BVC-SIG-START-reqNM-BVC-SIG-STOP-req

TRN-CONNECT-reqTRN-DECONNECT-req

TRN-NSE-Start-reqTRN-NSE-Stop-req

TRN-NSE-Capacity-ind

Figure 68 BSSGP interf aces, related to BVC-SIG entity


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 93/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 7.2.7 NSVC entity

The NSVC entity class is managed by NSC.NSVC instances are created by O&M.The NSVC entity class has the following attributes:

- NSVC id- NSEi- commited capacity (comited rate)- excess capacity- priority (for load-sharing)- administrative state (locked, unlocked)- operational state (read only attribute)- availability status (depends on SNS indications, related to the corresponding PVCoperational state)

- off-line: blocked by the peer- dependency: PVC disabled- failed: Reset on-going

SGSN(via SNS)

TRN-FAILURE-indTRN-AVAILABLE-ind

LM-NSVC-create-reqLM-NSVC-delete-reqLM-NSVC-SET-req(administrative state)

NSC

SNS

O&M

LM-NSVC-state-change-indLM-NSVC-ERR-CONF-ind

NSVC

NS-ALIVENS-BLOCKNS-UNBLOCKNS-RESET

Figure 69 NSC interf aces, related to NSVC entity

TRN-FAILURE-ind is sent when a PVC becomes “unavailable”.TRN-AVAILABLE-ind is sent when a PVC becomes “available”.

The possible state combinations are the following:

operat ional state availability status administrative state co mmentsdisabled off-line locked/unlocked blocked by the peerdisabled dependency locked/unlocked PVC disableddisabled failed locked/unlocked reset on-goingenabled 0 locked/unlocked


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 94/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 7.2.8 PVC entity

The PVC entity class is managed by SNS.PVC instances are created by O&M.The PVC entity class has the following attributes:

- PVC id- DLCI (identifier for the frame relay network)- BC id (Bearer Channel supporting the PVC)- NSVC id (one to one association with one NSVC instance)- CIR (Commited Burst Size)- EBS (Excess Burst Size)- AR (Access Rate)- operational state (read only attribute)- cause (to precise the operational state)

- deleted by network- unknown in network- inactive in network- new in network

Availability BitNew Bit

STATUS

TRN-FAILURE-indTRN-AVAILABLE-ind

LM-PVC-state-change-ind

LM-PVC-create-reqLM-PVC-delete-req

Network(FR)

SNS

O&M

PVC

NSC

Figure 70 SNS interf aces, related to PVC entity


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 95/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 7.2.9 BC entity

The BC entity class is managed by SNS.BC instances are created by O&M.The BC entity class has the following attributes:

- BC id- PCMI (PCM Identifier)- TS conf ( Time Slot configuration)- NTS (Number of Time Slots)- active DLCI (list of the active DLCI on this BC)- unknown DLCI (list of DLCI configured locally and unknown from the network)- not-configured DLCI (list of DLCI unknown locally and presented by the network)- operational state (read only attribute)- cause

- no reply from the network- loopback detected- invalid network behaviour- physical link error

STATUS ENQUIRYLM-BC-state-change-ind

LM-BC-create-reqLM-BC-delete-req

Network(FR)

SNS

O&M

BC

Figure 71 SNS interf aces, related to BC entity


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 96/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

7.3 Telecom layer initilisation

It is O&M responsibility to synchronise the initialisations of the different telecom layers.To initialise a telecom layer, O&M sends a CREATE related to the layer entity with all the parameterswhich are necessary to the telecom layer (e.g. timer values). The telecom layer performs itsinitialisation then acknowledges O&M which is thus able to schedule the whole initialisation phase.

7.4 Performance management

Performance counters are related to a monitored “entity” class. (each monitored entity instancehaving its counters)

For performance management purposes, 2 counter types are defined (see ITU-X721):

- counterA counter is regarded as associated with some event. The current value is incremented by “1” whenthis event occurs.A counter shall be reset at the end of the granularity period.A threshold may be associated.

c

qualityOfServicealarm report

threshold

granularityperiod

time

countervalue

c: counter value collected at theend of the first granularity period

Figure 72 counter type ch aracteristics


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 97/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

- gaugeThe gauge is the management abstraction of the value of a dynamic variable, such as the number ofconnections currently operated by a protocol machine.The value of the gauge is subject to change in either direction.A threshold may be associated and a hysteresis mechanism has to be provided to avoid the repeatedtriggering of event notifications when the gauge makes small oscillations around a threshold value.A tide-mark may be associated. It records the maximum or minimum value reached by a gaugeduring a measurement period.

qualityOfServicealarm report

threshold

granularityperiod

time

gaugevalue

lower tide-mark value, at the end ofthe granularity period

upper tide-mark value, at the end ofthe granularity period

Figure 73 gauge type ch aracteristics

Note: Only these raw counters are implemented at telecom layer level, ( CPU run-time has not to bewasted at this level, and more complex counters could be operator dependant), which means, forexample, that:

- average counters should be implemented with 2 counters at protocol level:- for percentage, for example: one counter for specific events and another one for allthe events. The percentage counter elaboration should be O&M responsability (orOMC-R?)

- time during which an entity is available or unavailable should be calculated by O&M, fromstate change notifications.

7.4.1 Counters creation

Counters are automatically created when the monitored entity instance is created.This monitored instance is created either by O&M or by the telecom layer. In the last case O&M hasto be notified, to take into account the created entity and its associated counters.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 98/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 7.4.2 Counters deletion

Counters are deleted when the monitored entity instance is deleted.This monitored instance is deleted either by O&M or by telecom layer. In the last case O&M has tobe notified, (current counter values are sent).

7.4.3 Counter periodical retrieval

O&M is responsible for periodical counter retrieval, according to the granularity period (GEToperation or a more sophisticated operation allowing, for example, to freeze all the counter values atthe very same instant, to have coherent results and then to read them before the next granularityperiod occurence).After this retrieval, counters are reset to zero (gauges are not reset)

7.4.4 Threshold handling

In telecom layers, after each counter incrementation, the value of the counter is compared with anassociated threshold (if any).Threshold values are modifiable, on a counter/gauge class basis.If the counter value reaches the threshold, a qualityofService alarm report is forwarded to O&M.

7.4.5 Tide-mark handling

A upper or/and a lower tide-mark may be associated to a gauge.At the beginning of the granularity period, tide-mark values are equal to the gauge value, then ateach gauge value variation, tide-mark values are compared with the gauge value:

- if upper tide-mark < gauge, then upper tide-mark = gauge- if lower tide-mark > gauge, then lower tide-mark = gauge

Tide-mark values are collected on granularity period periodicity.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 99/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8. GPRS SCENARIOS

The purpose of this paragraph is to present some GPRS scenarios

8.1 Paging for downlink packet transfer

MFS handles PS paging in the 3 network operation modes.An MS in STAND-BY state is paged by the SGSN before a DL transfer to that MS.The MS can either be addressed with TLLI or IMSI.The paging procedure shall move the MM state to READY to allow the SGSN to forward DL data tothe radio resource.Any data from the MS will be considered as a valid response to paging and will move the SGSNcontext to READY state.The SGSN supervises the paging procedure with a timer.

Note : the following numbers are related to Figure 74 and Figure 75.

1. The SGSN receives a downlink PDP PDU for an MS in STANDBY state

2. A GMM-PAGING-req is sent to SGSN BSSGP layer with the following parameters:- BVCI or LA or RA or BSS area- IMSI (in order to calculate the MS paging group)- [DRX parameters]- QoS profile- [P-TMSI]

and a PAGING-PS BSSGP PDU is sent to MFS.

3. A PACKET PAGING REQUEST (RLC/MAC control message) is sent to MSs on PCH or PPCH.

4. In order to answer to SGSN (with a LLC PDU), the MS shall establish an UL TBF, using aPACKET CHANNEL REQUEST; with cause value of ‘page response’, on (P)RACH

5. A PACKET UPLINK ASSIGNMENT is returned to the MS, on (P)AGCH.

6. The response to SGSN is sent in the UL allocated TBF.

7. Upon reception of the LLC PDU (implicit paging response), the SGSN stops the paging responsetimer and

8. starts the downlink transfer towards the MS’s cell (BVCI), by sending a BSSGP DL-UNITDATAwhich will trigger, in the MFS, a DL TBF establishment.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 100/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 8.1.1 PCCCH utilization

UL TBF

DL-UNITDATA

super-vision

timer(PAGCH)

(PPCH)

Packetpaging request (3)

LLC PDU (6)

Packet uplink assignment (5)

Packet channel request (4)(PRACH)

MS BTS BSC MFS SGSN

Paging PS (2)

PDP (1)

(8)

stand-by

Ready

(7)

Figure 74 Paging MSC, with P CCCH


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 101/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 8.1.2 CCCH utilization

UL TBF

super-vision

timer

DL-UNITDATA

(AGCH)

immediate assignment (5)

PS Paging

PDP (1)

LLC-PDU (6)

(RACH) (4)

(PCH) (3)

MS BTS BSC MFS SGSN

Paging PS (2)

Paging command

(7)

stand-by

channel request

ready

(8)

Figure 75 Paging MSC, with CCCH


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 102/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.2 Packet data transfer

8.2.1 Definitions

The X200 rules are applied:

N-1 PCI

N-PDU

N-1 SDU

N layer

N-1 layer

N-1 PDU

PDU: Protocol Data UnitSDU: Service Data UnitPCI: Protocol Control Information

Figure 76 Data unit mapping between adj acent layers (wit hout segmentation)

N-PDU

N-1 SDU

N layer

N-1 layer N-1 PCI

N-1 PDUN-1 PDU

Figure 77 Data unit mapping between adj acent layers (with segmentat ion)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 103/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 8.2.2 Packet data downlink transfer

A packet data downlink transfer has to be preceded by a paging procedure as shown on the followingfigure.

Packet Paging request

UL TBF establishment procedure(paging response)

MS MFS SGSN

STAND-BY

PDP PDU

PAGING PS

LLC PDU

DL packet data transfer procedureREADY

Figure 78 P acket data downlink transfer


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 104/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.2.2.1 PDU mapping

This paragraph indicates the mapping between data units in the different layers for a downlinktransfer.

radioblock

GCHframe

FR PDU

L3-PDUL3-PDU

GCHPDU

RLC-PDU

NS-PDU

BSSGP-PDU

LLC-PDU

BSSGP

L1bis

GSM-RF

MAC

RLC

LLC

BSSGP

NS

L1bisL2-GCH

L1-GCHGSM-RF

relay L2-GCH

L1-GCH

RLCrelay

MAC

MS BTS MFS SGSN

NS

LLC

Um Abis/Ater Gb

Figure 79 downlink PDU flow in the BSS

8.2.2.1.1 LLC PDU

L3 PDUaddressfield

controlfield

information field FCS

- address field- PD: protocol discriminator (LLC protocol or different protocol)- C/R: (command/response)- SAPI (GPRS MM, QoS priority level 1, level 2, level 3, level 4, SMS)

SAPI identifies a point at which LLC services are provided by a LLE (Logical LinkEntity) to a layer-3 entity.

- control field4 types of control field formats are specified:

- confirmed information transfer (I format)- supervisory functions (S format)- unconfirmed information transfer (UI format)- control functions (U format)

- information field (140 octets min., 1520 octets max.) (L3-PDU)

- FCS (Frame Check Sequence)It is a Cyclic Redundancy Check code which is used to detect bit errors in the header and

information fields of the LLC PDU.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 105/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.2.2.1.2 - BSSGP PDU

LLC PDUheader information field

- BSSGP header- PDU type (DL-UNITDATA)- TLLI (current)- QoS profile

- bit rate ( 0 to 6 553 500 bit/s)The “0” value means “best effort”

- precedence ( high/normal/low priority)- A-bit (acknowledged or unacknowledged RLC mode)- T-bit (LLC-PDU contains signalling (e.g. related to GMM) or data)

- PDU lifetime (PDU life time inside the BSS)- MS radio access capability- [priority] (priority of the PDU)- [DRX parameters] (SPLIT_PG_CYCLE code, non-DRX timer)- [IMSI]- [TLLI (old)]

8.2.2.1.3 NS PDU

BSSGP PDUPDU type(NS-UNITDATA)

BVCI information field

8.2.2.1.4 FR PDU

NS PDUsynchronisationflag

header information field FCS

- synchronisation flagAll frames shall start and end with a flag sequence equal to ‘01111110’.The closing flag may also serve as the opening flag of the next frame.

- header- DLCI (Data Link Control Identifier)- FECN (Forwarded Explicit Congestion Notification)may be set by a congested network to notify the user that congestion avoidance

procedures should be initiated where applicable for traffic in the direction ofthe frame carrying the FECN indication.

- BECN (Backward Explicit Congestion Notification)may be set by a congested network to notify the user that congestion avoidance

procedures should be initiated where applicable for traffic in the oppositedirection of the frame carrying the FECN indication.

- FCS (Frame Check sequence)

GP

RS

telecompresentation

ED

02released

MC

D256_02.D

OC

30/09/19993B

K11202

0256D

SZ

ZA

106/122




MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 107/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.2.2.1.5 RLC/MAC PDU

MACheader

RLCheader

RLC data spare bits

- MAC header- payload type (RLC data block)- RRBP (relative Reserved Block Period)- S/P (Supplementary/polling) (RRBP valid or not)- USF (Uplink State Flag)

- RLC header- TFI (Temporary Flow Identifier)

identifies the TBF (Temporary Block Flow) to which the RLC data block belongs- BSN (Block Sequence Number)

sequence number of each RLC data block within the TBF- FBI (Final Block Indicator)

indicates that the DL RLC data block is the last RLC data block of the DL TBF.- PR (Power Reduction) indicates the power level reduction of the next RLC blocks in

the PDCH, relative to the BCCH level.

- RLC dataEach LLC PDU shall be segmented into RLC data blocks.A RLC data block may contain octets from one or more LLC PDUs.The size of RLC data will depend on the coding scheme which will be applied on theradio interface:- CS1: 20 octets- CS2: 30 octets- CS3: 36 octets (not in step1)- CS4: 50 octets (not in step1)

- spare bitsThe size of this field depends on the coding scheme:- CS1: 0- CS2: 7 bits- CS3: 3 bits (not in step1)- CS4: 7 bits (not in step1)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 108/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.2.2.1.6 GCH PDU

RLC/MAC PDUheader information field

- GCH header- GCH PDU type (traffic)- DL block number- coding scheme- uplink burst (normal burst, access burst, no burst)- BS_TXPWR (BTS emission relative power)- CRC (Cyclic Redundancy Check)

- RLC/MAC PDU- CS1: 184 bits- CS2: 271 bits

8.2.2.1.7 GCH frame

GCH PDUsynchronisationpattern

information field

note: There are 2 GCH frame formats:- TRAU format for FUMO BTS- GCH format for other BTS(see [11] for more details)

8.2.2.1.8 radio block

RLC/MAC PDUinformation field BCS

4 radio bursts

- RLC/MAC PDU coded according to the coding scheme

- Block Check Sequence (BCS)

8.2.2.1.9 radio burst

radio burst time-slot<------------------------------------------------------------------------------------------------------->

tailbits(3)

encripted bits(58)

trainingsequence (26)

encripted bits(58)

tailbits(3)

guardperiod


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 109/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.2.2.1.10 Communication between layers

The following table gives- the primitives used to transfer data between adjacent layers- the main parameters exchanged with these primitives

communicationbetween

adjacent layers

primitives main parameters

LLC --> BSSGP(SGSN)

BSSGP-DL-UNITDATA-req - NSEI- BVCI- LSP-TLLI- QoS- PDU life time- radio access capability- DRX parameters

BSSGP --> NS(SGSN)

NS-UNITDATA-req - NSEI- BVCI- LSP

NS --> FR(SGSN)

DL-CORE-DATA-req - DLCI

FR --> NS(MFS)

DL-CORE-DATA-ind - DLCI

NS --> BSSGP(MFS)

NS-UNITDATA-ind - NSEI- BVCI

BSSGP --> RLC/MAC(MFS)

RL-DL-UNITDATA-ind - cell id.- TLLI- QoS- PDU life time- radio access capability- DRX parameters

RLC/MAC --> L2-GCH(MFS)

L2-GCH-UNITDATA-req - PDCHid- DL block number- uplink burst- coding scheme- BS-TXPWR

L2-GCH --> GSM-RF(BTS)

L2-GCH-UNITDATA-ind - PDCHid- DL block number- uplink burst- coding scheme- BS-TXPWR


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 110/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.2.2.2 Downlink flow control

DL flow control is performed on 2 entities:- cell (BVC)- and MS

For these 2 entities, bit rate information and average queuing delay , per BVC, are sent to the SGSN,for flow control purpose.

LLC-PDU BSSGP-PDU

SSGNBSSGP

MSflow

control

LLC-PDU

MFSRRM/RLC/MAC

MFSBSSGP

FLOW-CONTROL-MS FLOW-CONTROL-MSMS

FLOW-CONTROL-BVCcell

FLOW-CONTROL-BVCBVC

BVCflow

control

Figure 80 Downlink flow control

The BSS sends to the SGSN flow control parameters which allow the SGSN to locally control itstransmission output in the BSS direction.

Downlink flow control (FLOW-CONTROL-MS/BVC towards SGSN) is initiated at RRM layer level onthe following information (see Figure 81):

- at cell creation time the cell throughput is forwarded to the SGSN- On each received DL LLC-PDU, flow control mechanisms are performed on a MS basis

then on a cell (BVC) basis.RLC layer can notify a congestion on a MS basis (when a TBF transmission queue reaches an upperlimit) or for the whole DSP (on memory overload).The first notification will stop MS LLC-PDU at RRM layer level and the second one will stop LLC-PDU for the cells reached by this DSP.Of course as these notifications stop LLC-PDUs, they will have consequences on RRM flow controlmechanisms.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 111/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

flowcontrolind.

DSP

LLC-PDU

flowcontrolind. threshold

availablePDCH

capacity

LLC-PDURRM

RLC emissionqueue

BSSGP

FLOW-CONTROL-BVC

FLOW-CONTROL-MS

BVCflow control

LLC-PDUMSflow control

Figure 81 Downlink flow control triggers


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 112/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel 8.2.3 Packet data uplink transfer

8.2.3.1 PDU mapping

radioblock

GCHframe

FR PDU

L3-PDUL3-PDU

GCHPDU

RLC-PDU

NS-PDU

BSSGP-PDU

LLC-PDU

BSSGP

L1bis

GSM-RF

MAC

RLC

LLC

BSSGP

NS

L1bisL2-GCH

L1-GCHGSM-RF

relay L2-GCH

L1-GCH

RLCrelay

MAC

MS BTS MFS SGSN

NS

LLC

Um Abis/Ater Gb

Figure 82 Uplink PDU flow, in the BSS


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 113/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.2.3.1.1 LLC PDU

L3 PDUaddressfield

controlfield

information field FCS

- address field- PD: protocol discriminator (LLC protocol or different protocol)- C/R: (command/response)- SAPI (GPRS MM, QoS priority level 1, level 2, level 3, level 4, SMS)

SAPI identifies a point at which LLC services are provided by a LLE (Logical LinkEntity) to a layer-3 entity.

- control field4 types of control field formats are specified:

- confirmed information transfer (I format)- supervisory functions (S format)- unconfirmed information transfer (UI format)- control functions (U format)

- information field (140 octets min., 1520 octets max.) (L3-PDU)

- FCS (Frame Check Sequence)It is a Cyclic Redundancy Check code which is used to detect bit errors in the header and

information fields of the LLC PDU.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 114/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.2.3.1.2 RLC/MAC PDU

MACheader

RLCheader

[TLLI] information field spare bits

- MAC header- payload type (RLC data block)- countdown value

allows the MFS to calculate the number of RLC data blocks remaining for thecurrent UL TBF

- SI (Stall Indicator)indicates whether the transmit window can (or cannot) advance

- R (Retry)indicates whether the MS transmitted the Packet Channel request one time or moreduring its most recent channel access

- RLC header- TFI (Temporary Flow Identifier)

identies the TBF (Temporary Block Flow) to which the RLC data block belongs- BSN (Block Sequence Number)

sequence number of each RLC data block within the TBF- TI (TLLI Indicator)

indicates the presence of an optional TLLI field within the RRLC/MAC PDU

- RLC dataEach RLC data block may contain octets from one or more LLC PDUs.The size of RLC data will depend on the coding scheme which will be applied on theradio interface:- CS1: 20 octets- CS2: 30 octets- CS3: 36 octets (not in step1)- CS4: 50 octets (not in step1)

- spare bitsThe size of this field depends on the coding scheme:- CS1: 0- CS2: 7 bits- CS3: 3 bits (not in step1)- CS4: 7 bits (not in step1)

8.2.3.1.3 radio block

RLC/MAC PDUinformation field BCS

4 radio bursts

- RLC/MAC PDU coded according to the coding scheme

- Block Check Sequence (BCS)

- radio burst (see 8.2.2.1.9)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 115/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.2.3.1.4 GCH frame

GCH PDUsynchronisationpattern

information field

note: There are 2 GCH frame formats:- TRAU format for FUMO BTS- GCH format for other BTS(see [11] for more details)

8.2.3.1.5 GCH PDU

RLC/MAC PDUheader information field

- GCH header- GCH PDU type (traffic)- UL block number- block number error (to correct clock drifts between radio and GCH interfaces)- coding scheme (CS1/CS2)- RXQUAL (reception quality measured, by the BTS, on the radio interface)- RXLEV (reception level measured, by the BTS, on the radio interface)- CRC (Cyclic Redundancy Check)

- RLC/MAC PDU- CS1: 184 bits- CS2: 271 bits

8.2.3.1.6 - BSSGP PDU

LLC PDUheader information field

- BSSGP header (14 to 36 octets)- PDU type (UL-UNITDATA)- TLLI- QoS profile

- bit rate ( 0 to 6 553 500 bit/s)The “0” value means “best effort”

- precedence ( high/normal/low priority)- A-bit (acknowledged or unacknowledged RLC mode)- T-bit (LLC-PDU contains signalling (e.g. related to GMM) or data)

- cell identifier


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 116/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.2.3.1.7 NS PDU

BSSGP PDUPDU type(NS-UNITDATA)

BVCI information field

8.2.3.1.8 FR PDU

NS PDUsynchronisationflag

header information field FCS


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 117/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.2.3.1.9 Communication between layers

The following table gives- the primitive used to transfer data between adjacent layers- the main parameters exchanged with this primitive

communicationbetween

adjacent layers

primitives main parameters

GSM-RF --> L2-GCH(BTS)

L2-GCH-UNITDATA-req - PDCHid- UL block number- block number error- coding scheme- RXQUAL- RXLEV

L2-GCH --> RLC/MAC(MFS)

L2-GCH-UNITDATA-ind - PDCHid- UL block number- coding scheme- RXQUAL- RXLEV

RLC/MAC --> BSSGP(MFS)

RL-UL-UNITDATA-req - BVCI- NSEI- TLLI- QoS- cell identifier

BSSGP --> NS(MFS)

NS-UNITDATA-req - BVCI- NSEI- LSP- throughput indication- precedence

NS --> FR(MFS)

DL-CORE-DATA-req - DLCI

FR --> NS(SGSN)

DL-CORE-DATA-ind - DLCI

NS --> BSSGP(SGSN)

NS-UNITDATA-ind - BVCI- NSEI

BSSGP --> LLC(SGSN)

BSSGP-UL-UNITDATA-ind - NSEI- BVCI- TLLI- QoS- cell identifier


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 118/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.2.3.2 Uplink flow control

The purpose of this function is to adapt UL flow, according to Gb throughput and Gb congestionstate.

8.2.3.2.1 NSE capacity bandwidth adaptation

NSE throughput, on Gb interface is notified by BSSGP, with the following parameters:- NSE availability bandwidth (taking into account the throughput of the available NS-VCs)- NSE maximum bandwidth (taking into account the throughput of all the existing NS-VCs)

In case of NSE capacity bandwidth reduction the following procedure is activated, if enabled by anO&M parameter:

- The maximum number of available GCHs within the BSS is reduced from the percentage ofloss of bandwidth at Gb side.

- Ongoing traffic is not impacted (i.e. the number of active PDCHs is not reduced even if it isgreater than the number of GCHs allowed due to the NSE capacity bandwith reduction)

8.2.3.2.2 NSE congestion indication

A congestion situation is detected at PVC level by 2 means:- emission queue monitoring- BECN indication received from the FR network.

This congestion is notified to RRM, when all operational NS-VCs belonging to the same NSE arecongested. The following parameters are given:

- action (start/stop)- level 1 (only one level in B6.2)- NSE available bandwidth (current capacity of the NSE)- NSE maximum bandwidth (maximum capacity of the NSE)

In case of NSE congestion, the following procedure is undertaken, if enabled by an O&M parameter:- RRM stops the UL data traffic on one PDCH in each cell of the BSS where there is on-

going data traffic (by means of PDCH Release messages)- The MFS does not allocate any new PDCH in the BSS- This procedure is restarted periodically if the Gb congestion is still present.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 119/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.3 Autonomous cell reselection

When a cell reselection is autonomously determined by the MS (NC0), the MS may continue itsoperation in the old serving cell, while acquiring certain system information for the target cell.The operation in the old cell shall be aborted when one of the following conditions are met:- the MS station starts to receive information on PBCCH, in the target cell- the MS has received the SI13 message and there is no PBCCH present in the target cell- the criterions for camping on the old cell are no longer fulfilled.

While the operation is maintained in the old cell, the MS may suspend its TBF in order to receivenecessary information on BCCH in the target cell.It is performed without notification to the network.

Under no circumstances, operations in the old cell shall be continued more than 5s after a cellreselection has been determined

When a new cell has been selected, the MS shall perform a complete acquisition of (P)BCCHmessages.If there is a MPDCH, the MS shall not perform packet access in the selected cell until it has acquiredthe PSI1 message, a consistent set of PSI2 messages and made at least one attempt to receive thecomplete set of PSI messages.If there is no MPDCH, the MS shall not perform packet access in the selected cell until it hasacquired the SI3, SI13 and if present the SI1 messages and made at least one attempt to receiveother SI messages that may be scheduled within one TC cycle on BCCH.


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 120/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.4 Cell reselection during an UL transfer

Below is descibed, a reselection from cell A to cell B, during an UL TBF.

(1): (P)SI information is acquired

(2): When the operation in the old cell is aborted (i.e. the UL TBF is aborted), the MFS receivesno more messages in the UL blocks scheduled for this MS by the USF mechanism.N3101 is incremented in the MFS for each radio block allocated to that MS for which no datais received. When N3101 reaches N3101 max (default value = 16), radio resource

scheduling is stopped and T3169 is activated (USF and TFI values are frozen until T3169expiry).

(3): When (P)SI information has been acquired, an UL TBF is established in the new cell.

(4): The SGSN is informed of the cell change, when receiving a LLC PDU, in which the MFSadds the cell identifier.

UL LLC PDU (TLLI, cell A id.)UL TBF (cell A)

(4)

(3)

RLC/MAC data block (TLLI)

UL TBF establishment (cell B)

(2)(1)

MS MFS SGSN

(P)SIacquisition

UL LLC PDU (TLLI, cell B id.)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 121/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

8.5 Cell reselection during a DL transfer

Below is descibed, a reselection from cell A to cell B, during a DL TBF.

(1): (P)SI information is acquired

(2): When the operation in the old cell is aborted (i.e. the DL TBF is aborted), the MFS receivesno more acknowledgement from the MS, so an abnormal release is undertaken.

(3): When (P)SI information has been acquired, an UL TBF is established in the new cell. inorder to send a cell update to the SGSN.

(4): When receiving the new cell location, the SGSN sends a FLUSH to discard DL LLC PDUsbuffered for the MS in the old cell.

(5): The SGSN resumes the DL transfer by sending a DL LLC PDU which will trigger a DL TBFestablishment in the new cell.

(5)

(4)

UL LLC PDU (TLLI, cell B id.)

(2)(1)

MS MFS SGSN

(P)SIacquisition

(3)

RLC/MAC data block (TLLI)

UL TBF establishment (cell B)

FLUSH

FLUSH ACK

RLC/MAC data block

DL LLC PDU (cell B)DL TBF establishment (cell B)

DL LLC PDU (cell A)DL TBF (cell A)


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 122/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

9. TELECOM FUNCTIONAL BLOCKS

In the different telecom layers, functions have been split into 5 functional blocks:

- Packet C onnection Control (PCC)It is in charge of establishing, maintaining, releasing packet connections (e.g. TemporaryBlock Flow) for uplink or downlink paths.

- Packet Radio resource Ha ndling (PRH)It is in charge of controlling admission of packet connections and allocating them radioresources, by means of dynamic establishment or release of GPRS physical channels. It isalso responsible for monitoring the packet generated load on common channel, resulting indynamic allocation of master PDCH channels and control of usage of Packet Accesschannels. Finally it is in charge of the packet system information messages definition

- PAGing (PAG)It is in charge of addressing paging requests (circuit switched or packet switched) receivedfrom SGSN.

- TRaNsport (TRN)It transfers signalling and LLC PDUs between MS and SGSN.

- NeTwork Management (NTM)It implements the telecom parts of network management functions:

- transmission resources management- initialisation- performance monitoring

telecomlayern-1

telecomlayern

telecomlayern+1

NTMO&M PCC PRH PAG TRN

telecom layer Service Access Point

Figure 83 telecom functional blocks


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 123/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

10. GLOSSARY

BC Bearer ChannelBCCH Broadcast Control ChannelBCS Block Check SequenceBECN Backward Explicit Congestion NotificationBSC Base Station ControllerBSCGP BSC GPRS PartBSN Block Sequence NumberBSS Base Station SystemBSSAP Base Station System Application PartBTS Base Transceiver StationBVCI BSSGP Virtual Connection IdentifierCCCH Common Control ChannelCCU Channel CODEC UnitCS Coding SchemeCS paging Circuit Switched pagingDL DownLinkDLCI Data Link Control IdentifierDSP Digital Signalling ProcessorFBI Final Block IndicationFCS Frame Check SequenceFEC Forwarding Error CorrectionFECN Forwarded Explicit Congestion NotificationFR Frame RelayFSM Final State MachineGCH GPRS ChannelGGSN Gatway GPRS Support NodeGMM GPRS Mobility ManagementGPRS General Packet Radio ServiceGPU GPRS Processing UnitGSL GPRS Signalling LinkGSM-RF GSM Radio FrequencyIMSI Internatonal Mobile Subscriber IdentityLA Location AreaLAI Location Area IdentifierLLC Logical Link ControlLSP Link Selector ParameterMAC Medium Access ControlMAP Mobile Application PartMFS Multi Function ServerMPDCH Master PDCHMS Mobile StationMSC Mobile Switching CenterMTP2 Message Transfer Part Layer 2MTP3 Message Transfer Part Layer 3NM Network managementNS Network ServiceNSC Network Service ControlNSEI Network Service Entity IdentifierNSS Network Sub-SystemNS-VCI Network service - Virtual Connection IdentifierNS-VLI Network service - Virtual Link IdentifierNTM NeTwork ManagementPAGCH Packet Access Grant Channel


MCD 256_02.DOC30/09/1999 3BK 11202 0256 DSZZA 124/122

All

right

sre

serv

ed.P

assi

ngon

and

copy

ing

ofth

isdo

cum

ent,

use

and

com

mun

icat

ion

ofits

cont

ents

notp

erm

itted

with

outw

ritte

nau

thor

izat

ion

from

Alc

atel

PAG PAGingPACCH Packet Associated Control CHannelPBCCH Packet Broadcast Control ChannelPCC Packet Connection ControlPCCCH Packet Common Control ChannelPCI Packet Control InformationPCU Packet Control UnitPDCH Packet Data ChannelPDN Packet Data NetworkPDP Packet Data ProtocolPDU Protocol Data UnitPDTCH Packet Data Traffic ChannelPLMN Public Land Mobile NetworkPPCH Packet Paging ChannelPRACH Packet Random Access ChannelPRH Packet Resource HandlingPS paging Packet Switched pagingPSTN Public Switched Telephone NetworkPTCCH Packet Timing Control ChannelPTM Point To MultipointPTM-G Point To Multipoint-GroupPTM-M Point To Multipoint-MulticastPTP Point To PointPVC Permanent Virtual ChannelRA Routeing AreaRAI Routeing Area IdentifierRL ReLayRLC Radio Link ControlRRBP Relative Reserved Block PeriodRR Radio ResourceRRM Radio Resource ManagementRSL Radio Signalling LinkSAP Service Access PointSCCP Signalling Connection Control PartSDU Service Data UnitSGSN Serving GPRS Support NodeSM Session ManagementSNS Sub-Network ServiceTA (initial) Timing Advance (value)TAI Timing Advance IndexTBF Temporary Block FlowTC TransCoderTCAP Transaction Capabilities Application PartTCH Traffic CHannelTDMA Time Division Multiple AccessTFI Temporary Flow IdentityTLLI Temporary Logical Link IdentityTMSI Temporary Mobile Subscriber IdentityTRN TRaNsportTRX TransceiverTS Time SlotUL UpLinkUSF Uplink Status FlagVLR Visitor Location register

END OF DOCUMENT

Documents

GPRS Telecom Presentation