Gprs

行動通訊簡訊及多媒體訊息

溫志宏博士吳承崧博士蘇暉凱博士

國立中正大學電信研究中心

Outlines

課程內容：

GSM Introduction (3 hrs)

GPRS Introduction (3 hrs)

SMS & EMS (3 hrs) (Ref: 3GPP TS 23.040_MMS.pdf)

MMS (9 hrs) (Ref: 3GPP TS 23.140_MMSFD.pdf)

MMS Application (Java 2 Micro Edition) Programming (9 hrs)

實習：

MMS Application (Java 2 Micro Edition) Programming (9 hrs)

BSS

GPRS networkLogical network elements

GPRS Core

network

External

packet networ

ksValue added service

s (WAP)

GPRS networkLogical network elements

BTS BSC SGSN = Serving GPRS Support NodeGGSN = Gateway GPRS Support NodeNMS = Network Management SystemBG = Border GatewayCG = Charging GatewayFW = FirewallLIG = Lawful Interception Gateway

NMS

GGSN

GGSN

LIG

DNS

FW

Internet

BG

InterPLMNNetwork

SGSNCG

BillingCenter

GPRS Backbone

IntranetRouter Server

LAN

Corporate

FWOperatorServices

LAN

GGSN

SGSN & GGSN functionalities

BTS BSC

SGSN

GGSN Internet

GPRS Backbone IP Network

FW

SS7

HLRMSC/VLR

• GTP tunneling to SGSN• Interfaces to external IP networks• Charging & statistics• NMS interfaces

• Authentication• GTP tunneling to GGSN• Ciphering & compression• Mobility management• Interaction with HLR, MSC/VLR• Charging & statistics• NMS interfaces

SGSNSGSN

GGSNGGSN

• Mobility management• Authentication• Ciphering & compression• Protocol conversion• GTP tunneling to GGSN• Interaction with HLR, MSC/VLR • Charging & statistics• NMS interfaces

Functions……….

Serving GPRS Support Node (SGSN)

Gateway GPRS Support Node (GGSN)

• Essentially a router • Interfaces to external IP networks • GTP tunneling to SGSN• Charging & statistics• NMS interfaces

Functions……….

Border Gateway (BG)

• Essentially a router similar to GGSN • Provides a secure 'tunnel' for transferring data on the inter-PLMN backbone between different operators • Supports protocols like BGP-4

Functions……….

Domain Name Server (DNS)

• Standard IP device • Converts domain names into IP addresses • Based on a hierarchical & distributed model

Functions……….

Firewall (FW)

• Standard IP device • Protects against unauthorized access (hackers)

Functions……….

Charging Gateway (CG)

• Collects charging data from SGSN & GGSN • Processes the charging data & forwards it to the Billing System

Functions……….

Lawful Interception Gateway (LIG)

• Intercepts user data, MM information,

subscriber information etc. • Forwards it to Law Enforcement Agency (LEA)

Functions……….

GPRS InterfacesHLR

Air (Um)

GbGb

GsGr Gf

GnGn

GnGnInter-PLMN

GPRSBackbone

GpGp

Externalpacket network

GiGi

SGSN

EIR

BSC

MSC/VLR

SMS-GMSC

Gd

GGSN

BG

Signalling and data

Signalling

GaGa

CGGc

Abis

GGSN functionalities

GPRSBackboneLayers 1 & 2 Network layer

BTS BSC

SGSN

GGSN Internet

GPRS Core

Network

SS7

HLRMSC/VLR

TCP/UDP

IP

APP

L1

L2 PublicData Network Layers 1 & 2

Tunnelledpayload Network layer

Transport layer

Transport layer

GPRS tunnel

Application Layer

Server

L1

L2

IP

GTP

USERPAYLOAD

UDP

GPRS architecture key points (1)The Gateway GPRS Support Node (GGSN):

– acts as the interface between the GPRS network and external networks

– collects charging data and traffic statistics– can allocate IP-addresses for users– routes packets coming from external networks towards the

correct SGSN and vice versaServing GPRS Support Node (SGSN):

– converts protocols used in the IP backbone to protocols used in the BSS and the MS

– takes care of authentication and mobility management – routes data to the relevant GGSN when connection to an

external network is required – collects charging data and traffic statistics.

Mobility Management States– The tracking of the location of an MS depends on the

mobility management state. GPRS has three mobility management states.

• IDLE

• READY

• STANDBY

– Each state describes a certain level of functionality & information allocated.

– The change between the states happens upon activity or when a timer expires.

Mobility Management States• Idle State

– Subscriber is not attached to the GPRS network

– No valid MM context of the subscriber e.g. MS switched off

RA-1

VLR-1

HLR

SGSN-1BSC

IMSI 244...VLRIMSI

LAISGSN ?

IMSI ?RA ?Cell ?

LA-1

Mobility Management States• Ready State

– After successful GPRS Attach

– Location tracked to the cell level

– Activation & deactivation of PDP context possible

– Sending and receiving of SMS is possible

– MS can receive paging for circuit switched services (optional)

– Data can not be transferred until a PDP context is activated. After the PDP context activation, the SGSN can send data to the MS without paging at any time.

– Ready timer expiry moves MS to the STANDBY state

Mobility Management States• Standby State

– Subscriber is attached to the MM context

– Location tracked at RA level

– If SGSN receives a packet for the MS, it pages in the RA. A PDP context must be active.

– Activation of PDP context possible. If the MS sends data, it moves to the ready state.

– MS can receive paging for CS services (optional)

– The MS Reachable Timer starts ticking when the MS enters the Standby state & the MS is detached (IDLE state) upon its expiry (Implicit detach).

Mobility Management - GPRS Attach (1)

HLR

SGSN-1

BSC

RA-1

LA-1

2a 2b

11

(1) MS requests GPRS attach

(2a) The MS is not known in the PLMN so the SGSN requests

subscriber identity (first time)(2b) The MS sends its IMSI.

GPRS Attach (2) -Authentication

3d

3a

3b HLR

RA-1

SGSN-1

BSC

LA-1

3c

(3a) SGSN requests triplets from HLR (3b) The AC generates the triplets and hands them to the SGSN

(3c) The SGSN sends an Authentication Request to the MS(3d) MS sends back the Authentication ResponseThe SGSN performs the authentication

GPRS Attach (3) - IMEI checkEIR

SGSN-1

RA-1

BSC

LA-1

4a

4b

4c

4d

(4a) SGSN asks for the MS IMEI (4b) MS sends the IMEI

(4c) SGSN sends a Check IMEI message to the EIR

(4d) EIR replies with a Check IMEI ack that will include the list type

Mobility Management - GPRS Attach (4)

5b

SGSN-1

RA-1

BSC

LA-1

HLR

5a5c

5d

6a

6b

(5a) SGSN sends an Update location message to the HLR with the IMSI

(5b) The HLR responds by giving subscriber data to the SGSN (5c) The SGSN acknowledges that it has received the subscriber data ok (5d) The HLR ends the transaction with an Update Location acknowledge (6a) The SGSN accepts the GPRS attach and sends the MS a new P-TMSI (6b) The MS acknowledges that it has received the new P-TMSI

Session Management - PDP Context Activation

• One or more addresses can be assigned to an IMSI (MS).

• Contains mapping and routing information for transferring PDUs between MS and GGSN.

• Information includes: IP address, Access Point Name, QoS, Radio Priority, NSAPI, and LLC SAPI.

• Static addresses: address allocated by operator to an MS permanently and this address is stored in the HLR.

• Dynamic addresses: GGSN dynamically allocates and releases addresses as PDP contexts are activated and deactivated.

Process of assigning an IP address for becoming a part of the IP network

PDP context activationOverview

SGSN

RA-1

BSC

LA-1

3b GGSN

3a

12

4 1. Activate PDP context request

2. Auth. /IMEI check (optional)

3a. Create PDP context request

3b. Create PDP context response

4. Activate PDP context accept

PDP Context Activation - 1

BTS BSC

SGSN

GGSN

Intranet

GPRS Core

Network

SS7

HLR

DNS

1. MS sends "Activate PDP Context Request" to SGSN– Access Point Name– PDP Type (IP)– PDP Address (empty = dynamic)– QoS & other options

Internet

APN="Intranet.Ltd.com"

1

2

AccessPoint

2. SGSN checks Subscription data Access Point Name Dynamic / static IP address

PDP Context Activation - 2: Finding the GGSN

BTS BSC

SGSN

GGSN

GPRS Core

Network

DNS

3. SGSN gets the GGSN IP address from DNS APN maps to the GGSN IP address

Intranet

Internet

3

4

AccessPoint

4. SGSN sends "Create PDP Context Request" to GGSN PDP Type (e.g. IP) PDP Address (if empty=> dynamic address)

Access Point NameQoS & other options

PDP Context Activation - 3Access Point Selection

BTS BSC

SGSN

GGSN

GPRS Core

Network

DNS

• Access Point Name refers to the external network the subscriber wants to use– Physical/logical interface in

GGSN• Access Point configuration in GGSN

defines where to connect the user

Intranet

Internet

APN="Intranet.Ltd.com"

PDP Context Deactivation

•The MS or the network can deactivate a PDP context.

•Every address can be deactivated separately, but performing a GPRS Detach will automatically remove all the PDP contexts.

SMS data transfer

MSC

G-MSC

SGSN

HLR

SMSC

1) SMS

2)4a)

4b)

a) MSC addressb) SGSN address

2). Send routing info. for Short Message (GMSC-HLR) Send routing info. for Short Message result (HLR-GMSC)

3b)

3a)

PDP Context Activation - 4Context Activated

BTS BSC

SGSN

GGSN

GPRS Core

Network

• User authenticated OK (non-transparent case)• User dynamic IP address allocated by

RADIUS server, or DHCP server, or GGSN internal pool

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

Intranet

Internet

5

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

• SGSN now ready to route user traffic between MS and GGSN

GPRS Attach v/s PDP Context Activation

• GPRS Attach

– MOBILITY MANAGEMENT PROCEDURE

– Establishes a logical link between the MS and the SGSN.

– Makes the MS available for SMS over GPRS, paging via SGSN, and notification of incoming GPRS data.

– Transmission of user data is not possible

• PDP Context Activation

– IP address is assigned to the MS.

– Makes the MS known in the corresponding GGSN.

– SESSION MANAGEMENT PROCEDURE

Context Activation for a Roaming User (0)

SGSNSGSN

HOMEOperator

GPRS

BG

BG

.GPRSDNS

Inter-PLMNGPRS

Backbone

DNSDNS

GGSN

Visited Operator

DNSHOME


SGSNSGSN

Embassy Intranet

Singapore GPRS

Backbone

HOMEOperator

GPRS

BG

BG

.GPRSDNS

Inter-PLMNGPRS

Backbone

DNSDNS

GGSN

GSM OPERATOR, Finland

Visited Operator, Singapore

DNSHOME

2

1

3


SGSN

Embassy Intranet

Singapore GPRS

Backbone

HOMEOperator

GPRS

BG

BG

.GPRSDNS

.GPRSDNS

Inter-PLMNGPRS

Backbone

DNSDNS

GGSN

GSMOPERATOR, Finland


DNSHOME

4

5


SGSN

Embassy Intranet

Singapore GPRS

Backbone

HOMEOperator

GPRS

BG

BG

.GPRS DNS

Inter-PLMNGPRS

Backbone

DNSDNS

GGSN



DNSHOME

DNSHOME

6

7


SGSNSGSN

Embassy Intranet

Singapore GPRS

Backbone

HOMEOperator

GPRS

BG

BG

.GPRSDNS

Inter-PLMNGPRS

Backbone

DNSDNS

GGSNGGSN



DNSHOME

8

9

The Data Flow in a Roaming Case

SGSN

Embassy Intranet

Singapore GPRS

Backbone

HOMEOperator

GPRS

BG

BG

Inter-PLMNBackbone

GGSN



Connection options

SGSN Singapore GPRS

Backbone

HOMEOperator

GPRS

BGBG

GGSNGGSN

Internet

GGSNGGSN

Embassy Intranet

Inter-PLMNBackbone

BGBG

Gp

Gp

Gi

Gi

Roaming, Dynamic IP-address from Home Network, APN Always the Same

SGSNSGSN

HOMEOperator

GPRS

BG

BG

Inter-PLMNGPRS

Backbone

GGSN

Visited Operator

Access Point

IP address changesGGSN

Visited-PLMNGPRS

Backbone

Internet/Intranet

Roaming, Dynamic IP-address from a Visited Network

SGSNSGSN

HOMEOperator

GPRS

BG

BG

Inter-PLMNGPRS

Backbone

GGSN

Visited Operator

Access Point

x.x.x.xGGSN

Visited-PLMNGPRS

Backbone

Internet

Charging of GPRS services

SGSN

OperatorIP backbone

GGSNBorder Gateway

Inter operatorIP network Internet

Billing SystemCharging gateway

Nokia GPRS Charging Gateway:

* receives CDRs generated by SGSN and GGSN•consolidates and merges CDRs to a suitable format for BS

GTP'

GTP'

GGSN Charging Functions

CG

Internet

GGSN

OperatorIP backbone

SGSN

G-CDRs

GGSN CDR (PDP context data) : G-CDRStart collection:

- PDP context activationStop collection:

- PDP context deactivationCollected information e.g.

- Traffic volumes uplink/downlink- QoS negotiated- Duration- SGSN & GGSN address- Access Point Name

SGSN Charging Functions

SGSN CDR (PDP context data) : S-CDRStart collection:

- PDP context activationStop collection:

- PDP context deactivationCollected information e.g.

- Traffic volumes uplink/downlink- QoS requested/negotiated- Duration- SGSN & GGSN address- Access Point Name

Mobility Management CDR : M-CDRStart collection:

- GPRS activation / Incoming SGSN RA update

Stop collection:- GPRS deactivation / Outgoing SGSN RA update

Collected information - Location changes

CG

S-CDRsM-CDRsSMS-CDRs

Internet

GGSN

OperatorIP backbone

SGSN

CG Functionality

• CDR collection from GSNs (CG receives the CDRs with GTP')

• intermediate storage for CDRs

• CDR validation

• CDR consolidation

• CDR formatting

• adaptation to different CCB System interfaces

• to reduce the CDR processing load of the CCB System

Main tasks of CG are:

GPRS Charging introduces new billing concepts

GSMtraffic

GPRStraffic

Ratingbased on:

Dialled digits Access Point NameIP Address Allocation

Usagebased on:

Call durationSMS transaction

Data VolumeContext durationSMS transaction

Intermediaterecords:

NecessaryNot needed

Roaming case 1

SGSN

GGSNAPN

Operator AIP backbone

GGSNAPN

Operator BIP backbone

Internet

Border Gateway

SGSNCG

CG

CCB CCB

HOMENETWORK

VISITINGNETWORK

CLEARING

Visitor

SGSN

GGSNAPN

Operator AIP backbone

GGSNAPN

Operator BIP backbone

Internet

Border Gateway

SGSNCG CG

CCB CCB

CLEARING

VISITINGNETWORK

HOMENETWORK

Visitor

Roaming case 2

APN (Access Point Name)

•APN=Network ID+Operator IDExample:internet201.kgt.com,tw.mnc088.mcc466.gprs

•Selection Mode*SentByMS: MS-provided APN, subscription not verified.*Subscribed: MS or Network-provided APN, subscription verified.*ChosenBySGSN: Network-provided APN, subscription not verified.

•The SGSN select the APN to be used to derive the GGSN address•Wild Card APN: The user can select whichever APN he wants

MS Request ?

N

Y

Wild Card ?

Y

ChosenBySGSN

N

Single PDP in HLR?

Y

SubscribedPDP Context Activate Reject

Wild Card ?

N

SubscribedSentByMSN

Y

Selection Algorithm

IMSI .................... 46688xxxxxxxxxxxxxSGSN ADDRESS ............ MT-SMS VIA SGSN ......... NNETWORK ACCESS .......... BOTH

PDP CONTEXT ID .......... 1

PDP TYPE ................ IPv4PDP ADDRESS .............VPLMN ALLOWED ........... N PRECEDENSE CLASS ........ 2DELAY CLASS ............. 4RELIABILITY CLASS ....... 2 PEAK THROUGHPUT CLASS ... 9MEAN THROUGHPUT CLASS ... 31APN ..................... *

Wild Card APN in HLR

3 PDP Context in HLR

IMSI .................... 46688xxxxxxxxxxxxxSGSN ADDRESS ............ MT-SMS VIA SGSN ......... NNETWORK ACCESS .......... BOTH

PDP CONTEXT ID .......... 1

PDP TYPE ................ IPv4PDP ADDRESS .............VPLMN ALLOWED ........... N PRECEDENSE CLASS ........ 2DELAY CLASS ............. 4RELIABILITY CLASS ....... 3 PEAK THROUGHPUT CLASS ... 9MEAN THROUGHPUT CLASS ... 31APN ..................... internet

(Gn VLAN)

INTERNET

ggsn01

ggsn04

Dns-2

sgsn-01

BG1

MS1Roaming APN :x.x.x.x

MS1

BSS

MS2

mnc088.mcc466.gprsmnc088.mcc466.gprs

HLR

Roaming connectivity

Dns-1

Gp VLAN1

.

DCN Router

IT Router

E1 Lambda ATM PVC

Router Router

Routerggsn01

ggsn02

sgsn

(Gn VLAN)

(Gn VLAN)

ggsn01

ggsn02

sgsn

ggsn03sgsn-02

BSS

ggsn02

ggsn03

BSS

HutchisonRoot DNS

GRX connectivity (via internet)

Aicent

Gn Vlan

BG

GGSN

SGSN

BSS

MS

MS1

BG2

Vlan

VPN via internet

HLR

SS7

Documents

Gprs