Packet switched-Core

Provided by: Soroush Ghamari

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Packet Switched • What is GPRS?

– General Packet Radio Service

• Why GPRS? – In order to provide the data service out the scope of the fixed network

• GPRS network classification – GSM GPRS

– UMTS GPRS

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Some Abbreviation

• GPRS: General Packet Radio Service

• TE : Terminal equipment

• MT: Mobile terminal

• BSS: Base Station Subsystem

• UTRAN: UMTS Terrestrial Radio Access Network

• SGSN: Service GPRS Support Node

• GGSN: Gateway GPRS Support Node

• CG: Charging Gateway

• OCS: online charging system

• PCRF: Policy and charging rules function

• BG: Bordering Gateway

• PDN: Packet Data Network

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Some Abbreviation

• MSC/VLR: Mobile Switch Center/Visitor Location Register

• SMS-GMSC: Gateway MSC For Short Message Service

• SMS-IWMSC: Short Message Service Interworking MSC

• SCP: Service Control Point

• GMLC: Gateway Mobile Location Center

• HLR: Home Location Register

• EIR: Equipment Identity Register

• CDR: Customer Data Records

• VOBB: Voice Over Broadband Business

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Network topology

Internet

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Network topology

PCRF OCS

Gy Gx

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NETWORK ENTITY: Serving GPRS Support Node (SGSN)

• GPRS Mobility Management (GMM)

• The mobility management functions are used to keep track of the current location of an MS within the PLMN or within another PLMN.

• Session management • Session Management function manages the PDP

context of MS.

• Security management • Identify and authenticate the subscriber identity and

check the validity of service requests of subscribers so that only valid subscribers can access services provided by the network.

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• GMM Main procedures • Attach procedure • Detach • RAU • Service request • Purge function

• Session management procedures • PDP context activation • PDP context deactivation • PDP context modification • PDP context preservation

• Security Management • Authentication • User Identity Confidentiality • User Data and Signaling Confidentiality • Identity Check

NETWORK ENTITY: Serving GPRS Support Node (SGSN)

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NETWORK ENTITY: Getaway GPRS Support Node (GGSN)

• QOS and traffic management • What is QOS? • QOS classification

1. Conversational 2. Streaming 3. Interactive 4. Background

• What is traffic management?

• Charging • Can be bases on time or volume • Offline charging

o By GGSN and CG and BS. o Sending generated eG-CDRs and to CG. o The standard charging data is sent to a billing system (BS) for

final processing. • Online charging

o By GGSN and OCS. o Sending online charging information to OCS on Gy Diameter

interface.

• Admission control • Routing • Dynamic IP allocation

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NETWORK ENTITY: Charging Gateway (CG)

• Real-time collection of GPRS CDRs

• Temporary storage and buffering of GPRS CDRs

• Pre-processing of GPRS CDRs

• Sending GPRS CDRs to the mediation and billing

system

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NETWORK ENTITY: Policy and Charging Rules Function (PCRF)

• Usage based dynamic policy

• Duration based dynamic policy

• Period based dynamic policy

• Service-zone based dynamic policy

• Roaming-region based dynamic policy

• Rating based dynamic policy

• Subscriber notification

• Quota Reset

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• Saving and updating GPRS subscriber subscription data

• User authentication

• Providing location/routing information and processing

needed in mobility management and routing, for example

Saving and updating user service SGSN number and

address

GPRS user location deletion indication

Whether MS is reachable

• Subscriber tracing (optional)

NETWORK ENTITY: HLR

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• The PDP context is Packet Data Protocol context

• PDP context contains all the information needed to transfer user data between MS and GGSN.

• A primary PDP context records the following information: • PDP type

• PDP address

• QOS

• APN resolution

• PDP context exists in MS, SGSN, GGSN and RNC.

Important Concept: PDP context

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Deactivate PDP Context

or

MM state change to IDLE

or PMM-DETACHED

Activate PDP

Context

INACTIVE

ACTIVE

Active：can transmit data

Important Concept: PDP states

Inactive：cannot transmit data

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• PDP Type o IPV4 o IPV6 o PPP

• PDP Address o Static IP

o Is defined in HLR o Public or Private (Valid or invalid)

o Dynamic IP o Allocates by GGSN o Valid or invalid

Important Concept : PDP Type and PDP Address

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• APN structure:

•Operator ID : fixed extension, must end with “.gprs”

•Network ID shall not end with “.gprs”

•MNC: mobile network code

•MCC: mobile country code

•Rightel.mnc20.mcc432.gprs

Important Concept : Access Point Name (APN)

Network ID.mnc<MNC>.mcc<MCC>.gprs

Network Identifier

Operator Identifier

(PDP Type, PDP Address, Access Point Name,

QoS Requested)

Charging ID allocation

IP address

3G -GGSN

7. Activate PDP Context Accept

3. Create PDP Context Response

2. Create PDP Context Request

1. Activate PDP Context Request

3G -SGSN UTRAN MS

4. Radio Access Bearer Setup （Qos）

C1

C2

6. Update PDP Context Response

5. Update PDP Context Request

Important Concept : PDP activation procedure

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• MS start and send “Active PDP context request” to SGSN

Provide QoS parameter

Provide a APN-NI

Provide a static IP or null

• Receive ACCEPT from SGSN

If the QoS not accept by MS, then starts delete PDP context

procedure.

PDP activation procedure : MS

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• Check subscriber data

• APN selection default APN, APN provide from MS and the APN subscribed in HLR

APN-NI.APN-OI.GPRS

• QoS negotiation

QoS provided from MS, default QoS , QoS subscribed in HLR

• Send message “create PDP context request” to GGSN

• RAB assignment

• Send message “active PDP context accept” to MS

Dynamic IP address

QoS

PDP activation procedure : SGSN

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• Check the APN provided by SGSN

• QoS negotiation

• Allocate a dynamic IP to the MS

• Allocate a charging ID for the PDP context

• Return a CREATE PDP CONTEXT ACCEPT message to SGSN

Dynamic IP

QoS

Charging ID

Other information

• Update PDP context

PDP activation procedure : GGSN

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• E-mail from fixed to mobile network

BTS/NodeB

SGSN

MS

BSC/RNC

GGSN Backbone

ISP

Access server

Mail server

e-mail

HLR

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• E-mail from mobile to fixed network

BTS/NodeB

SGSN

MS

BSC/RNC

GGSN Backbone

ISP

Access server

Mail server

e-mail

HLR

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Thank you