P. P. Mahale

GSM n/w corporate offices

IP phone/PC

Intranet

GSM/BTS

Architecture

MSC

VLR

HLR

Gateway

Access

node

Service

node

Terminal mobility:

User mobility:

They communicate with each other using H.323 protocol

Service node: user mobility, controls calls, translate

addr, authentication

Access node: manage connection, mobility & radio

resources, related to core n/w & BTS nodes

GSM/BTS: wireless access for GSM MS in IP addr

Gateway: interface GSM on net & other n/w.

Terminal equipment: can be IP phone, PC

1) The H.323 Network:

packet based n/w

H.323 terminal

* optionally included

H.323 architecture

H.323

Gatekeeper

H.323

Gatew

ay

H.323

Multipoint

Control unit

MP*

MC*MP*

MC*

MC*

MP*

MC

ISDN

LAN

PSTN

Terminal:

Gateway

Gatekeeper

MCU(multipoint control unit):

MC( multipoint controller):

MP(multipoint processor):

2) The iGSM architecture:

GSM MAP & H.225 RAS (registration, admission & status)

GSM/PSTN/IP call setup & release

Every iGSM gatekeeper is assigned ISDN no.

It is recognized by HLR, also maintain DB.

We can connect iGSM gateways & gatekeeper.

MS

BTS/BSC

H.323 terminal

IP n/w

iGSM architecture

GSM

MSC

VLR

HLR

iGSM

gatew

ay

Gatekeeper

iGSm VLR

Describes registration, dereg & call delivery.

Database can be distributed among several gate

keepers.

MSISDN of the MS

Transport addr of H.323 terminal

Password of the iGSM subscriber

HLR addr (ISDN no)

IMSI of the MS

User profile, indicates service features & restrictions

Presence indication of iGSM

MS Registration

1

BTS/BSC

H.323 terminal

7

8 6 IP n/w

5 3 2

4 5 4

3 6

Movement from the GSM n/w to IP n/w

GSM

MSC

VLR

HLR

iGSM

gatew

ay

Gatekeeper

iGSm VLR

H.323 Gatekeeper Gateway HLR OLD VLR

term

2.RRQ(MSISDN, pwd)

3.IRQ( loc, IMSI, VLR, MSC)

3.MAP_UPDATE_LOC(IMSI, VLR, MSC)

4.MAP_INSERT_SUBSR_DATA(user profile)

4.IRR(INSSUBS DATA,user profile)

5.IRQ(inssubdataack) 7.MAP_CANCEL_LOC

8.MAP_CANCEL_LOC_ack

5.MAP_INSERT_SUB_DATA_ack

6.MAP_UPDATE_LOC_ack(HLR no)

6.IRR(updateLocAck, HLR no)

6.RCF

Message flow for iGSM registration

Gatekeeper H.323

HLR Gateway (old VLR) term

MAP_CANCEL_LOC(IMSI)

IRR(CanLoc, IMSI)

URQ

UCF

MAP_CANCEL_LOC_ack IACK(CanLocAck)

Message flow for iGSM deregistration

12 H.323 terminal

11

3 7 IP 10

2 8 n/w 9

6

2 5

GSM 3 4 2 3

1

originating

1

PSTN

HLR

GM

SC

s/w

iGSM

Gate

way

Gatekeeper

iGSM VLR

Ori GMSC HLR Gateway Gatekeeper H.323

s/w VLR term

1.IAM 2.MAP_SEND_ROUTING_INFO(MSISDN)

2.MAP_PROVIDE_ROAMING_NO(IMSI)

2.LRQ(RoamNo, IMSI)

3.LCF(RoamNoAck, MSRN)

3.MAP_PROVIDE_INFORMATION_NO_ack(MSRN)

3.MAP_SEND_ROUTING_INFO_ack(MSRN)

4. IAM 5. ARQ

6. ACF

7. Setup

8. Call Proceeding

9. ARQ

10. ACF

11. ACM 11. ACM 11. Altering

12. ANM 12. Connect

12. ANM

Conversation

GPRS functional group:

N/w access:

Standard point to point data transfer

Registration of MS

Authentication & authorization

Admission control which communicates with MS

Msg screening

Charging information collection

Packet routing & transfer function:

Route the data betwn Ms & destinations

Relay function used by BSS

Fwd packets betwn BSS & serving or gateway GSN

Routing.

Addr translation & mapping

Encapsulation & tunneling,

Compression & ciphering

Logical link management:

Communication channel betwn MS & GSM n/w

Logical link establishment

Logical link release

Radio resource management:

Allocates & maintenance radio communication path

Um mgmnt- radio resources allocated

Cell selection

Um-tranx- packet data transfer capability

Path management: maintains communication path

D

A Gs Gr Gc

Um Gb Gn Gi

Gn Gp

other GPRS n/w

---------- Signaling Interface

________ signaling and Data Transfer Interface

MSC/VLR

GGSNSGSN

GGSNSGSNBSSMS

HLR

PDN

In this architecture all respective system are modified.

Service GPRS support nod(SGSN):

----> GPRS equivalent to the MSC

Gateway GPRS support nodes(GGSN):

----> interworking with external packet switched

networks.

Gr & Gc follows the GSM mobile application part(MAP).

A, Gs, Gr, Gc & D are used for signaling, without

involving user data transmission in GSM.

Interface Um, Gb, Gn, Gp & Gi are used for both

signaling & transmission in GPRS.

In BSS Um & Gb use Logical link control(LLC) & packet data

units(PDU)

In SGSN Gb & Gn use Packet data protocol(PDP) & PDU’s

Three GPRS terms

-- Mobility Management

-- PDP context

-- QoS

IDLE-> MS is not attached to the GPRS mobility management

STANBY-> MS is attached to GPRS MM but not obtained

detailed location information

READY-> loc information for MS has been identified on cell

levels

In GPRS attach procedure both to MS & SGSN are moved to

ready.

PDP context stored in MS, HLR, SGSN & GGSN contains

mapping & routing information for packet transmission .

PDP context activation

-- MS known to GGSN

-- communication to external n/w is possible.

-- terminal supports several IP address

When MS is detached all PDP context are deactivated.

PDP context can be two states ACTIVE & INACTIVE.

Reliability class-- residual error rates for data loss, out of

sequence delivery, & corrupted data

Precedence class– three transmission policy

Delay class-- four delay level

Peak throughput– max data transmission rate

Mean throughput– avg data transmission rate

Mobile station:

Transceiver consist of 2 section:

RF front end:

--This section converts the GSM/TDMA signal baseband

signal in I/Q form

GPRS signaling & data codes:

--This section encodes/decodes signaling msg for

GSM/TDMA BSS

--Transcends data into packets conforming with GPRS

specifications

MS Modes:

Class A: MS can operate simultaneously packet & ckt

s/w services.

Class B: MS can operate either one at one time.

Class C: Ms can operate only packet s/w services

GPRS aware SIM are:

IMSI:

(P-TMSI) packet temporary mobile subscriber identity

Addr of routing area

Current ciphering key

BSC must get a packet control unit to

--set up, supervise & disconnect packet switching calls

--also support cell change, radio resource confi & ch

assignments

MSC/VLR, HLR & SMS center must be enhanced for

interworking with GPRS

MS must be equipped with GPRS

Paging & mobility management for GPRS

PCU & TRAU is equivalent for packet data service

SGSN(service GPRS support node):

It is equivalent to that of MSC/VLR

It provide ciphering, MM, routing msg, billing report

IMSI & MSISDN no.

MM state

Routing area identity & cell identity

New SGSN buffered packets should be forwarded

Authentication & ciphering parameters

PPF(paging proceed flag)

GGSN(Gateway GPRS support node):

GGSN is primarily provisioned by router

It supports sub addr, mapping addr, routing, counting

& tunneling packets.

It contain DHCP(dynamic host configuration

protocol) to allocates IP addr.

PDP type & PDP addr

Dynamic addr indication

Access point name & charging ID

It stores current SGSN addr & profile of the user in

its location register

HLR:

Shared DB with GSM

Is enhanced with GPRS sub data & routing info

It keeps user profile, current SGSN & PDP addr info

SGSN exchange info with HLR

VLR:

It is responsible for a group of location areas

It stores data of only those users area responsibility

IMSI & MSISDN

It contact SGSN to request loc info or paging of voice

calls

Um interface:

1. Radio channel structure:

Packet paging ch- pages MS for both ckt-s/w, packet data

service

Packet access grant ch(PAGCH)- used in packet transfer

establishment

Packet notification ch- used to send point to point

multipoint

Packet broadcast ctrl ch(PBCCH)- specify for packet data

Packet associate control ch(PACCH)- convey signaling info

Packet timing advance control ch in uplink direction

(PTCCH/U)- transmission of addr.

MS N/W

1. PRACH (packet ch req)

phase 1 2. PAGCH (packet immediate assign)

3. PACCH (pack resource req)

phase 2(optional) 4. PACCH (pack resource assign)

5. PDTCH (data block)

Uplink transfer 6. PDTCH (data block)

7. PDTCH (resource req)

Resource reallocation 8. PACCH (pack resource assignt)

9. PACCH (pack resource reassign ack)

Uplink transfer 10. PDTCH (data block)

11. PDTCH (last data block)

12. PACCH (final pack ack/nack)

Fig. GPRS uplink packet transfer

2. Um protocol layers:

It include RF layers, physical link layer, radio link ctrl/

medium access ctrl

PLL provides service for information transfer over

physical layer

RLC/MAC provides info transfer GPRS.

Retransmission, buffering & reassembly.

3. Enhance data rates for GSM evolution:

Enhanced data rate for GSM evolution(EDGE)

Enhanced GPRS(EGPRS) provides higher data rate.

Spectrum efficiency is also higher

MS measured downlink perfo sends to BSS

BSS measures uplink MSC’s

BSS sends uplink MSC cmd to MS

Gb interface:

Allowing many users to multiplexed over same resource

Resource allocation when data actually delivered

It include LLC, base station, n/w service layer.

LLC is convey information betn MS & SGSN.

To maintain a sequential order of frames

Flow control

Format & operational errors, recovery of transmission

Maintain by MS moves bet cell

Provide GPRSMM(GMM)

Includes authentication & transport

1. N/W service:

NS layers delivers encapsulated packets

SGSN & BSS connects frame relay link.

It supports n/w service virtual links(NS-VLs)

The path is called as NS-VC

Blocking when NS-VC not available

Unblocking when path is available

Resetting, a new NS-VC is set-up

Testing to check end to end connection

2. BSS GPRS protocol:

Provides QoS & routing info to transmit used data

SGSN communicates multiple BSS, corresponding one

BSSGP is work

It uses DL-UNITDATA to deliver from SGSN to BSS

It uses UL-UNITDATA to deliver from BSS to SGSN

PDU is delivered from SGSN to BSS

PDU contain MS radio access capability, QoS profile.

GMM provides PAGING, SUSPEND & RESUMd

BSSGP supported FLOW CONTROL

Downlink buffer is not transfer to MS

Gn & Gp interface:

Uses GPRS tunneling protocol (GTP)

Tunnels user data signaling msg to GSN’s

Gn i/f GSN within the same GPRS n/w

Gp i/f GSN within the different GPRS n/w

Supported by TCP for connection oriented transmission

Supported by UDP for connectionless transmission

Tunnel is two way, point to point.

Band signaling separated from data tunnels.

GTP tunnel management:

It creates, update & delete tunnels.

Create_PDP_context_request send to GGSN with DNS.

New entry allows route & charge packet

TCP & UDP transport user data

Send update msg to modify packet

Redistributed for load balancing.

GTP mobility management:

Support GPRS attach, routing area update, activate PDP

Send identification to new SGSN.

SGSN_context_req send to old SGSN obtain MM

After receive SGSN send response msg

after receiving send ack

Gs Interface:

It connects to DB in MSC/VLR & SGSN

Not involve user data transmission

BSSAP+functionality of Gs i/f

Loc info IMSI & GPRS attach

Paging, suspend, resume & loc update proc

VLR send GPRS_paging to SGSN

New paging msg send back to VLR

Uses suspend msg to block GPRS

If MS unknown send suspend_failure

Send Resume msg to activate GPRS

Resume_ack

GPRS_loc_update_req

Loc update reject & accept

Gi Interface:

PSDN & PDP work thr GPRS

These are interworking entities

PSDN uses X.25 & X.75

PDN uses IP & PPP

It is dynamically assigned by GPRS

GPRS work with GGSN via IPV4 & IPV6

GPRS maintain a firewall restrict the IP appln

GPRS & GGSN manages the DNS

GPRS may transparently access internet

DNS send identification instead of MS

GPRS nontransparent access intranet via ISP

Ms must authenticate intranet using security

Either provide a Ipsec for confidentiality

1. GPRS attach & detach procedure:

1.1 Attach req

1.2 Identfn_req

1.2 Identfn_responce

1.3 Attach Accept

Attach message flow

MSNew

SGSN

Old

SGSN

GGS

NHLR

VLRBSS

RA/LA update

2.1 MAP_cancel_loc

2.2 Detach_req

2.3 Delete_PDP_context_req

2.3 Delete_PDP_context_resp

2.4 GPRS_attach_ind

2.5 Detach Accept

2.6 MAP_cancel_loc_ack

Detach message flow

MSSGS

N

GGS

NHLR

VLRBSS

2. PDP context procedure:

1.1 Active PDP context req

1.2 create PDP context req

1.2 create PDP context res

1.3 Active PDP context accept

PDP context activation message flow

MS SGSN GGSNBSS

2.1 Update PDP context req

2.1 Update PDP context res

2.2 Modify PDP context req

2.2 Modify PDP context res

PDP context update message flow

MS SGSN GGSNBSS

3.1 Delete PDP context req

3.1 Delete PDP context res

3.2 Deactivate PDP context req

3.2 Deactivate PDP context res

PDP context deactivate message flow

MS SGSN GGSNBSS

1. The combine RA/LA update procedure:

1. Routing area update req

2. SGSN_context_req

2. SGSN_context_res

2. SGSN_context_ack

(pack fwding)

3. Update PDP context req

3. Update PDP context res

4. Map_update_loc

4. Map_cancel_loc

4. Map_cancel_loc_ack

4. Map_insert_sub_data

4. Map_insert_sub_data_ack

4. map_update_loc_ack

5. GPRS_loc_updating_req

MSNew

SGSN

Old

SGSN

GGS

NHLRNew

VLRBSS