All IP Mobile

8/2/2019 All IP Mobile

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Wireless and Mobile All-IP Networks


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Contents [1/3]

Short Message Service and IP Network Integration

Mobility Management for GPRS and UMTS

Session Management for Serving GPRS SupportNode

Session Management for Gateway GPRS Support

Node

Serving Radio Network Controller Relocation forUMTS


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Contents [2/3]

UMTS and cdma2000 Mobile Core Networks

UMTS Charging Protocol

Mobile All-IP Network Signaling

UMTS Security and Availability Issues

VoIP for the Non-All-IP Mobile Networks

Multicast for Mobile Multimedia Messaging

Service Session Initiation Protocol


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Contents [3/3]

Mobile Number Portability

Integration and WLAN and Cellular Networks

UMTS All-IP Network Issues on IP Multimedia Core Network Subsystem

A Proxy-based Mobile Service Platform


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Short Message Service and IP Network

Integration

GSM SMS Network Architecture


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SMS-IP Integration: SM-SC-based

Mobile

Network

SM-SC Gateway

IP

Network

In most commercial implementations, SMS and IP networks

are integrated through SM-SC.


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NCTU-SMS


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iSMS


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Mobility and Session Management

Three types of mobility: radio mobility, core network

mobility and IP mobility

Radio mobility supports handoff of a mobile user during

conversation

Core network mobility provides tunnel-related

management for packet re-routing in the core network

due to user movement

IP mobility allows the mobile user to change the access

point of IP connectivity without losing ongoing sessions.

Session management maintains the routing path for a

communication session, and provides packet routing

functions including IP address assignment and QoS setting.


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Mobility Management for GPRS and

UMTS


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LAs, RAs, URAs, and Cells


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Session Management for Serving GPRS

Support Node


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Session Management for Gateway GPRS

Support Node

The GGSN plays the role as a gateway, which

controls user data sessions and transfers the data

packets between the UMTS network and theexternal PDN.

The meta functions implemented in the GGSN are

described as follows: network access control,

packet routing and transfer, and mobilitymanagement.


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Access Point Name (APN)

UTRAN

(3) ISP

GGSN

RADIUS

server

DHCP

server

FW

NAT

(1) INTERNET

(2) WAP

(4) COMPANY

RADIUS

server

RADIUS

server

DHCP

serverSignalingSignaling and data

DHCP: Dynamic Host Configuration Protocol

FW: Firewall

GGSN: Gateway GPRS Support Node

MS: Mobile Station

NAT: Network Address translator

RADIUS: Remote Authentication Dial-In User Service

UMTS: Universal Mobile Telecommunication Service

UTRAN: UMTS Terrestrial Radio Access Network

(5)

(6)

(7)

(8)(9) (10)

SGSN

DNS

HLR

(11)

(12) (13)


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IP Address Allocation

APN label INTERNET WAP ISP COMPANYAccess

mode

Transparent Transparent Non-

transparent

Non-

transparent

IP address

allocation GGSN/DHCPGGSN/

DHCP

DHCP/

RADIUS

RADIUS

IP address

type

IPv6/IPv4 IPv4 IPv4 IPv4


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GGSN

SGSN1 SGSN2

Node B1 Node B2

UE

Iur

Iub Iub

RNC2RNC1

(Source RNC) (Target RNC)

Serving RNC

Drift

RNC

GGSN

SGSN1 SGSN2

Node B1 Node B2

UE

Iur

Iub Iub

RNC2RNC1

(Source RNC) (Target RNC)

Serving RNC

Serving Radio Network Controller

Relocation for UMTS


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Lossless SRNC Relocation

In 3GPP TS 23.060, a lossless SRNC relocation procedurewas proposed for non-real-time data services.

1. The source RNC first stops transmitting downlink packets tothe UE, and then forwards the next packets to the target

RNC via a GTP tunnel between the two RNCs.2. The target RNC stores all IP packets forwarded from the

source RNC.

3. After taking over the SRNC role, the target RNC restarts the

downlink data transmission to the UE. No packet is lost during the SRNC switching period.

Real-time data transmission is not supported because the IPdata traffic will be suspended for a long time during SRNCswitching.


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Fast SRNC RelocationStage I

TargetRNC

SourceRNC

GGSN

2 4

3

Iur

SGSN1 SGSN2

1

Stage I (the same as Stage I in SD) initiatesSRNC relocation.

The IP packets are delivered through the oldpath: UENode B2target RNCsource RNCSGSN1GGSN

Steps 1 and 2: Source RNC initiates SRNCrelocation by sending Relocation_ Required toSGSN1.

Step 3: SGSN1 sends Forward_Relocation_Request to request SGSN2 to allocate the

resources for the UE. Step 4: SGSN2 send Relocation_Request with

RAB parameters to the target RNC. After allnecessary resources are allocated, the targetRNC send Relocation_Request_ Acknowledgeto SGSN2.


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Fast SRNC RelocationStage II

GGSN routes the downlink packets to the oldpath receiving Update_PDP_Context_ Request.

After GGSN has received the message, thedownlink packets are routed to the new pathGGSNSGSN2target RNC.

The new packets arriving at the target RNCare buffered until the target RNC takes over theSRNC role.

Step 5: SGSN2 sends Update_PDP_Context_Request to GGSN. GGSN updates the

corresponding PDP context, and the downlinkpacket routing path is switched from the oldpath to the new path.

Steps 6-7: SGSN2 informs SGSN1 that allresources for the UE are allocated. SGSN1forwards this information to the source RNC.

GGSN

SGSN1

Iur

6

5

7

SGSN2

SourceRNC TargetRNC


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Fast SRNC RelocationStage III

The Iur link (i.e., the old path) disconnected.The old downlink packets arriving at thesource RNC later than Step 7(Relocation_Command) are dropped.

The SRNC role is switched from the sourceRNC to the target RNC.

Step 8: The source RNC transfers SRNScontext (e.g., QoS profile) to the target RNC.

Steps 9 and 10: The target RNC informs

SGSN2 that the target RNC will become theSRNC. At the same time, the target RNCtriggers the UE to send the uplink IP packetsto the target RNC.

GGSN

9

10

Iur

8

SGSN1 SGSN2

Source

RNC

Target

RNC


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Fast SRNC RelocationStage IV

The target RNC informs the sourceRNC that SRNC relocation issuccessfully performed. Then the

source RNC releases the resources forthe UE.

Step 11: The target RNC indicates thecompletion of the relocation procedureto SGSN2, and SGSN2 forwards this

information to SGSN1. Step 12: SGSN1 requests the source

RNC to release the resources allocatedfor the old path.

GGSN

11

11

12

SGSN1 SGSN2

Source

RNC

Target

RNC


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UMTS and cdma2000 Mobile Core

Networks

UMTS and cdma2000 are two major standardsfor 3G mobile telecommunication.

Two important functionalities of mobile corenetwork are mobility management and sessionmanagement.

This chapter describes these two

functionalities for UMTS and cdma2000, andcompare the design guidelines for these two3G technologies.


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cdma2000 CS Domain

BSC connects to the core network through the

SDU.

The SDU distributes the circuit switched traffic

(e.g., voice) to the MSC.

A1 interface supports call control and mobility

management between MSC and BSC.

A2 and A5 interfaces support user traffic andcircuit switched data traffic between MSC and

BSC.


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cdma2000 PS Domain

The SDU distributes the packet switched traffic to PCF and

then to the PDSN.

Interfaces A8 and A9 support packet switched data and

signaling between PCF and SDU, respectively. Interfaces A10 and A11 (R-P interface) support packet

switched data and signaling between PCF and PDSN.

GRE tunnel is used for data routing in A10 with standard

IP QoS. MIP is used for signaling routing in A11.

The R-P interface also supports PCF handoff (inter or intra

PDSN).


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PDSN

Maintaining link-layer sessions to the MSs

Supporting packet compression and packet filtering before the

packets are delivered through the air interface

Providing IP functionality to the mobile network, which routesIP datagrams to the PDN with differentiated service support

Interacting with AAA to provide IP authentication,

authorization and accounting support

Acting a MIP FA in the mobile network The interfaces among the PDN nodes (i.e., PDSN, HA, AAA)

follow the IETF standards.


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cdma2000 Control Plane

IP

PPP

LAC

MAC

L1

LAC

MAC

L1 PL PL

Link

Layer

PL

IP

PPP

PL

IP /IPSec

Link

Layer

MS RN PDSN HA

UDP

MIP

IP/IPSec

UDP

IKEMIP MIPIKE

UDP

R-P R-P

IKE: Internet Key Exchange IP: Internet Protocol

IPSec: IP Security HA: Home Agent

LAC: Link Access Control MAC: Medium Access Control

MIP: Mobile IP MS: Mobile Station

PDSN: Packet Data Serving Node PPP: Point to Point Protocol

PL: Physical Layer RN: Radio Network

R-P: RN-PDSN Interface UDP: User Datagram Protocol


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UMTS Control Plane

GMM/SM/SMS

RRC

RLC

MAC

L1

RLC

MAC

L1ATM

UTRAN SGSN GGSN

RRC RANAP

AAL5L1

SCCP

SignalingBearer

GMM/SM/SMS

UDP/IP

L2

MS

ATM

RANAP

AAL5

SCCP

SignalingBearer

GTP-C

L1

L2

GTP-C

UDP/IP

ATM: Asynchronous Tranfer ModeGGSN: Gateway GPRS Support Node

MS: Mobile Station

RLC: Radio Link Control

SGSN: Serving GPRS Support Node

GMM/SM/SMS: GPRS Mobility Management/Session Managemnt/Short Message Service

GTP-C: GPRS Tunneling Protocol - Control Plane


AAL5: ATM Adaptation Layer Type 5

MAC: Medium Access Control

RANAP: Radio Access Network Application Protocol

RRC: Radio Resource Control

SCCP: Signaling Connection Control Part


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cdma2000 User Plane

IP

PPP

LAC

MAC

PL PL

LinkLayer

PPP

LinkLayer

PL

IP

LinkLayer

MS RN PDSN HA

PLL1

LAC

MAC

L1

R-P

PL

R-P

IP/

IPSec

IP

IP/

IPSec

IP: Internet Protocol IPSec: IP SecurityHA: Home Agent LAC: Link Access Control

MAC: Medium Access Control MS: Mobile Station

PDSN: Packet Data Serving Node PPP: Point to Point Protocol

PL: Physical Layer RN: Radio Network

R-P: RN-PDSN Interface UDP: User Datagram Protocol


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UMTS User Plane

IP,

PPP

PDCP

RLC

MAC

L1

RLC

MAC

L1 ATM L1

IP,

PPP

MS UTRAN SGSN GGSN

PDCP GTP-U

UDP/IP UDP/IP

L2AAL5 AAL5

GTP-U

UDP/IP

L2

ATM L1

GTP-U

UDP/IP

GTP-U

ATM: Asynchronous Tranfer ModeGGSN: Gateway GPRS Support Node

IP: Internet Protocol

MS: Mobile Station

PPP: Point to Point Protocol

SGSN: Serving GPRS Support Node


AAL5: ATM Adaptation Layer Type 5

GTP-U: GPRS Tunneling Protocol - User Plane

MAC: Medium Access Control

PDCP: Packet Data Convergence Protocol

RLC: Radio Link Control

UDP: User DatagramProtocol


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Protocol Stacks [1/2]

The control plane carries out tasks for MM/SM/SMS.

In cdma2000, the mobility and session tasks are based on the

same lower layer protocol (IP based protocols) for user data

transportation.

In UMTS, the lower layer protocols supporting MM/SM tasks

in the control plane are different from the lower layer protocols

in the user plane.

The signaling path between MS and SGSN consists of an

RRC connection between MS and UTRAN, and an Iuconnection between UTRAN and SGSN.


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Protocol Stacks [2/2]

In UMTS, the PS domain services are supported by PDCP in the

user plane.

PDCP contains compression methods, which provide better

spectral efficiency for IP packets transmission over the radio. In cdma2000, the header and payload compression mechanism is

provided by PPP between MS and PDSN.

Both UMTS RLC and cdma2000 LAC provide segmentation and

retransmission services for user and control data. cdma2000 LAC supports authentication functionality for

wireless access, which is equivalent to GPRS transport layer

authentication in UMTS.


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PPP

In both control and user planes for cdma2000, PPP is carriedover the LAC/MAC, and R-P tunnels are utilized to establishthe connection between an MS and the PDSN.

In cdma2000, a PPP connection is equivalent to a packet data

session, which is comparable to the UMTS PDP context. In the UMTS control plane, no PPP/IP connection is established

between MS and SGSN. Signaling is carried over the RRC andIu connections.

UMTS user plane provides two alternatives for IP services.

IP is supported by non-PPP lower layer protocols.

IP is supported by PPP.

Dial-up application

Mobile IP is introduced to UMTS


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UMTS Charging Protocol

The GTP protocol is used for communications between a GSN and a CG,

which can be implemented over UDP/IP or TCP/IP.

Above the GTP protocol, a Charging Agent(or CDR sender) is

implemented in the GSN and a Charging Serveris implemented in the CG.

Node B

Node B

RNC

RNC

UTRAN

HLR

SGSN GGSN

Core Network

MS

MS

CG: Charging Gateway UTRAN : UMTS Terrestrial Radio Access Network

GGSN : Gateway GPRS Support Node RNC: Radio Network Controller

HLR: Home Location Register SGSN: Serving GPRS Support Node

MS: Mobile Station Node B : Base Station

PDN: Packet Data Network

PDN

signalingsignaling and data

gd

e

ab c

CG

Gn

Ga

Gi

f


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The GTP Service Model

Our GTP service model follows the GSM MobileApplication Part (MAP) service model.

A GSN communicates with a CG through a dialog byinvoking GTP service primitives.

A service primitive can be one of four types: Request (REQ)

Indication (IND)

Response (RSP)

Confirm (CNF)Service

(Confirm)Service

(Request)

GTP' Service User

(Charging Agent)

GTP' Service

Provider

UDP/IP

Dialog Initiator (GSN)

Service(Indication)

Service(Response)

GTP' Service User

(Charging Server)

GTP' Service

Provider

UDP/IP

Dialog Responder (CG)

GTP' Message

(Response)

GTP' Message

(Request)


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GTP Connection Setup

Before a GSN can send CDRs to a CG, a GTP connection

must be established between the charging agent in the

GSN and the charging server in the CG.

ChargingAgent

GTP' ServiceProvider

ChargingServer

(2) Node Alive Request

(5) Node Alive Response

(1) CONNECT (REQ)

GSN CG

GTP' ServiceProvider

(3) CONNECT (IND)

(4) CONNECT (RSP)

(6) CONNECT (CNF)


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GTP CDR Transfer

The charging agent is responsible for CDR generation in a GSN. The

CDRs are encoded using, for example, the ASN.1 format defined in

3GPP 32.215. The charging server is responsible for decoding the

CDRs and returns the processing results to the GSN.

Charging

Agent

GTP' Service

ProviderCharging

Server

(2) Data Record Transfer Request

(1) CDR_TRANSFER (REQ)

GSN CG

GTP' Service

Provider

(3) CDR_TRANSFER (IND)

(4) CDR_TRANSFER (RSP)

(6) CDR_TRANSFER (CNF)

(5) Data Record Transfer Response


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GTP Failure Detection

In a GSN, an entry in the CG list represents a GTP' connection to a CG. The CG Address attribute identifies the CG connected to the GSN.

The Statusattribute indicates if the connection is active or inactive.

The Charging Packet Ack Wait TimeTris the maximum elapsed time the GSN isallowed to wait for the acknowledgement of a charging packet.

TheMaximum Number of Charging Packet TriesL is the number of attempts

(including the first attempt and the retries) the GSN is allowed to send a chargingpacket.

TheMaximum Number of Unsuccessful DeliveriesKis the maximum number ofconsecutive failed deliveries that are attempted before the GSN considers a connectionfailure occurs.

The Unsuccessful Delivery CounterNKattribute records the number of the consecutivefailed delivery attempts.

The Unacknowledged Bufferstores a copy of each GTP' message that has been sent to

the CG but has not been acknowledged. A record in the unacknowledged buffer consists of anExpiry Timestampte , the Charging

Packet Try CounterNL and an unacknowledged GTP' message.


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Path Failure Detection Algorithm

Step 1. After the connection setup procedure is complete, bothNL andNK

are set to 0, and the Statusis set to active. At this point, the GSN can

send GTP messages to the CG.Step 2.When a GTP message is sent from the GSN to the CG at time t, a

copy of the message is stored in the unacknowledged buffer, where theexpiry timestamp is set to te=t+ Tr.

Step 3. If the GSN has received the acknowledgement from the CG beforete, bothNL andNKare set to 0.

Step 4. If the GSN has not received the acknowledgement from the CGbefore te ,NL is incremented by 1. IfNL=L, then the charging packetdelivery is considered failed.NK is incremented by 1.

Step 5. IfNK=K, then the GTP connection is considered failed. TheStatusis set to inactive.

The Path Failure Detection Algorithm (PFDA) detects pathfailure between the GSN and the CG. PFDA worksas

follows:


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Mobile All-IP Network Signaling

Traditional SS7 signaling is implemented in MTP-basednetwork, which is utilized in the existing mobile networksincluding GSM and GPRS.

In UMTS all-IP architecture, the SS7 signaling will becarried by IP-based network.

The low costs and the efficiencies for carriers to maintain asingle, unified telecommunications network, guarantee thatall telephony services will eventually be delivered over IP.

This chapter describes design and implementation of the IP-based network signaling for mobile all-IP network.


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SS7 Architecture

STP pair STP pair

SCP

STP pair

A-link

B-link

C-link

D-link

E-link

F-linkSSP SSP

A-linkA-link

Trunk

NETWORK 1NETWORK 2

Voice/Data Trunk

SS7 Signaling Link

Service Switching Point (SSP) is a telephony switch that performs callprocessing.

Service Control Point (SCP) contains databases for providing enhanced

services.

Signal Transfer Point (STP) is a switch that relays SS7 messages

between SSPs and SCPs.


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Access Links (A-links) connect the SSP/STP or the SCP/STP

pairs.

Bridge Links (B-links) connect STPs in different pairs.

Cross Links (C-links) connect mated STPs in a pair. Diagonal Links (D-links) are the same as the B-links except

that the connected STPs belong to different SS7 networks.

Extended Links (E-links) provide extra connectivity between

an SSP and the STPs other than its home STP. Fully-Associated Links (F-links) connect SSPs directly.

SS7 Link Types


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SS7 Protocol Stack

MTP1

MTP2

MTP3

SCCP

MAP

OSI Model

Physical

Data Link

Network

PresentationSession

Transport

Application

OMAP

TCAP

The SS7 Layers

ISUP


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Message Transfer Part (MTP) consists of three levels

corresponding to the OSI physical layer, data link layer, and

network layer, respectively.

The MTP level 1 (MTP1) defines the physical, electrical, and functionalcharacteristics of the signaling links connecting SS7 components.

The MTP level 2 (MTP2) provides reliable transfer of signaling messages

between two directly connected signaling points.

The MTP level 3 (MTP3) provides the functions and procedures related to

message routing and network management.

Signaling Connection Control Part (SCCP) provides additional

functions such as Global Title Translation (GTT) to the MTP.

SS7 Protocol Stack: MTP & SCCP


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Integrated Services Digital Network User Part (ISUP)establishes circuit-switched network connections (e.g., for callsetup).

Transaction Capabilities Application Part (TCAP)

provides the capability to exchange information betweenapplications using non-circuit-related signaling.

Operations, Maintenance, and Administration Part(OMAP) is a TCAP application for network management.

Mobile Application Part is a TCAP application that supportsmobile roaming management.

SS7 Protocol: ISUP, TCAP, MAP


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IETF Signaling Transport (SIGTRAN) working group addresses

the issues regarding the transport of packet-based SS7 signaling

over IP networks.

SIGTRAN defines not only the architecture but also a suite of

protocols, including the SCTP and a set of user adaptation layers

(e.g. M3UA), which provides the same services of the lower

layers of the traditional SS7.

Why not TCP ?

TCP provides strict order-of-transmission which causes head-of-line

blocking problem.

The TCP socket does not support multi-homing.

TCP is vulnerable to blind Denial-of-Service (DoS) attacks such as

flooding SYN attacks.

Stream Control Transmission

Protocol (SCTP)


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Like TCP

To provide reliable IP connection.

To employ TCP-friendly congestion control (including slow-start,

congestion avoidance, and fast retransmit)

Unlike TCP

To provide message-oriented data delivery service and new delivery

options (ordered or unordered)

To provide selective acknowledgments for packet loss recovery

To use a four-way handshake procedure to establish an association (i.e., aconnection).

To offer new features that are particularly for SS7 signaling

Multi-homing

Multi-streaming

SCTP Features


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Multicast for Mobile Multimedia

Messaging Service

Short Message Service (SMS) allows mobile subscribers tosend and receive simple text message in 2G systems (e.g.GSM).

Multimedia Message Service (MMS) is introduced todeliver messages of sizes ranging from 30K bytes to 100Kbytes in 2.5G systems (e.g. GPRS) and 3G systems (e.g.UMTS)

The content of an MMS can be text (just like SMS),

graphics (e.g., graphs, tables, charts, diagrams, maps,sketches, plans and layouts), audio samples (e.g., MP3 files),images (e.g., photos), video (e.g., 30-second video clips),and so on.


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MMS Architecture [1/2]


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MMS Architecture [2/2]

TheMMS user agent (a) resides in a Mobile Station (MS) or anexternal device connected to the MS, which has an application layerfunction to receive the MMS.

The MMS can be provided by the MMS value added serviceapplications (b) connected to the mobile networks or by the external

servers (d)(e.g., email server, fax server) in the IP network. The MMS server (c) stores and processes incoming and outgoing

multimedia messages.

The MMS relay (e) transfers messages between different messagingsystems, and adapts messages to the capabilities of the receivingdevices. It also generates charging data for the billing purpose. The

MMS server and the relay can be separated or combined. The MMS user database (f) contains user subscriber data and

configuration information.

The mobile network (g) can be a WAP (Wireless Application Protocol)based 2G, 2.5G or 3G system. Connectivity between different mobilenetworks is provided by the Internet protocol.


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Short Message Multicast Architecture

VLR1 1VLR2 2

VLR3 0

MCH (HLR)

LA1 0

LA2 1

MCV (VLR1)

LA3 0

LA4 2

MCV (VLR2)

LA5 0

LA6 0

MCV (VLR3)


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MMS Multicast [1/2]

RA1 0

RA2 1

RA3 0

RA4 2

RA5 0

RA6 0

MCc (CBC)


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MMS Multicast [2/2]

Step 1. The multimedia message is first delivered from the messagesender to the Cell Broadcast Entity (CBE).

Step 2. The CBE forwards the message to the Cell Broadcast Center(CBC).

Step 3. The CBC searches the multicast table MCC to identify therouting areas RA

iwhere the multicast members currently reside (i.e.,

MCC [RAi] > 0 in the CBC). In Figure 1.7, i = 2 and 4.

Step 4. The CBC sends the multicast message to the destination RNCs(i.e., RNC1 and RNC2 in Figure 1.7) through the Write Replacemessage defined in 3GPP TS 23.041.

Step 5. The RNCs deliver the multimedia messages to the multicast

members in the RAs following the standard UMTS cell broadcastprocedure.

Like SMS multicast, a multicast table MCC is implemented in the CBCto maintain the identities of the RAs and the numbers of the multicastmembers in these RAs.


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Session Initiation Protocol

SIP is an application-layer signaling protocol over the IPnetwork.

SIP is designed for creating, modifying and terminatingmultimedia sessions or calls.

SIP message specifies the Real-Time Transport Protocol /Real-Time Transport Control Protocol (RTP/RTCP) thatdeliver the data in the multimedia sessions. RTP is a transport protocol on top of UDP, which detects packet

loss and ensures ordered delivery.

A RTP packet also indicates the packet sampling time from thesource media stream. The destination application can use thistimestamp to calculate delay and jitter.


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Network Elements: User Agent

The user agent resides at SIP endpoints (or phones). A user agentcontains both a User Agent Client (UAC) and a User Agent Server(UAS). The UAC (or calling user agent) is responsible for issuing SIP requests

The UAS (or called user agent) receives the SIP request and responds tothe request.

(a) SIP UA Developed in the National Chiao

Tung University(b) Windows Messenger 4.7-based SIP

UA (with phone number 0944021500)


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Network Elements: Network Servers

Registrar: A UA can periodically register its SIP URI and

contact information (which includes the IP address and the

transport port accepting the SIP messages) to the registrar.

Proxy Server: A proxy server processes the SIP requests.

The proxy server either handles the request or forwards it

to other servers, perhaps after performing some translation.

Redirect Server: A redirect server accepts the INVITE

requests from a UAC, and returns a new address to thatUAC.


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SIP Registration and Call Setup

1. REGISTER

2. Store

3. OK

4. INVITE

5. Query

6. INVITE

7. Trying

8. Ringing

10. ACK

10. ACK

SIP UAS SIP UACRegistrar SIP Proxy

LocationService

9. OK9. OK

Registration

Call

setup8. Ringing

7. Trying


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Mobile Number Portability

Number Portability (NP) is a network function that allows

a subscriber to keep a unique telephone number.

NP is an important mechanism

to enhance fair competition among telecommunication operators

and

to improve customer service quality.

Three types of NP are discussed:

location portability, service portability, and

operator portability.


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Terminologies

Number range holder (NRH) network : thenetwork which the number is assigned

Subscription network: the network with which thecustomers mobile operator has a contract to

implement services for a specific mobile phonenumber

Donor (release) network: subscription networkfrom which a number is ported in the porting

process

Recipient network: network that receives thenumber in the porting process


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MDN vs MIN

An MS is associated with two number. Mobile directory number (MDN) is dialed to reach the

MS (e.g., MSISDN in GSM).

Mobile identification number (MIN) is a confidential

number that uniquely identifies an MS in MobileNetwork (e.g., IMSI in GSM).

When mobile number portability is introduced, a

porting mobile user would keep the MSISDN (the

ported number) while being issued a new IMSI in

GSM.

Simplified GSM Call Termination


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Simplified GSM Call Termination

Procedure without NP

Step 1: After calling party dials the MSISDN of MS2, the call route

to the GMSC of MS2.

Step 2: GMSC query HLR to query the location of MS2.

Step 3: The call is routed to the destination MSC and eventually set

up.


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Call Routing Mechanism with NP

In 3GPP TS 23.066, two approaches are proposed

to support number portability call routing:

Signaling Relay Function (SRF)-based solution, and

Intelligent Network (IN)-based solution.

Both approaches utilize the Number Portability

Database (NPDB) that stores the recodes for the

ported numbers.


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SRF-based Approach

The SRF node is typically implemented on the

Signal Transfer Point (STP).

Three call setup scenarios have been proposed for

SRF-based approach: direct routing (DR) andindirect routing (IR).

DR: The mobile number portability query is

performed in the originating network.

IR: The mobile number portability query is

performed in the NRH.


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DR Call Setup Scenario 1

Step 1: After calling party dials the MSISDN of MS2, the call is routed to the GMSC of theoriginating network.

Step 2: The GMSC queries SRF for the subscription network information of MS2.

Step 3: By consulting the NPDB, the SRF obtains the subscription network information,

and forwards it to the originating GMSC.

Step 4: The originating GMSC routes the call to the subscription GMSC (i.e., GMSC ofMS2). The call is then set up following the standard GSM procedure.


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DR Call Setup Scenario 2

Step 1: After calling party dials the MSISDN of MS2, the call is routed to the GMSC of the originating network.

Step 2: The GMSC queries SRF for the subscription network information of MS2.

Step 3: By consulting the NPDB, the SRF obtains the subscription network information. If the originating network is

the subscription network of MS2, then SRF forward message to query HLR to obtain the routing information of

MS2.

Step 4: The information will then be returned to the originating GMSC. Then call is set up following the standard

GSM procedure.

Integration and WLAN and Cellular


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Integration and WLAN and Cellular

Networks

Service aspects

Access control aspects

Security aspects

Roaming aspects

Terminal aspects Naming and address

aspects

Charging and billingaspects

UMTS: Universal Mobile telecommunication System HLR: Home Location RegisterUTRAN: UMTS Terrestrial Radio Access Network PDN: Packet Data NetworkRNC: Radio Network Controller WGSN: WLAN-based GPRS Support NodeSGSN: Serving GPRS Support Node AP: AccessGGSN: Gateway GPRS Support Node MS: Mobile Station


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WLAN/Cellular Integration Scenarios

Service Capabilities Scenario 1 2 3 4 5 6

Common Billing

Common Customer Care

Cellular-based Access Control

Cellular-based Access Charging

Access to Mobile PS Services

Service Continuity

Seamless Service Continuity

Access to Mobile CS Service with Seamless Mobility


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The MS Architecture

Retrieve the SIM information.

Perform MS Attach and detachprocedure.(The authentication action isincluded in the attach procedure.)

Set up network Configuration.


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UMTS All-IP Network

Mobile system history

The advantages of evolution from UMTS R99 to all-IP network

Mobile network will benefit from all existing Internet applications.

The telecommunications operators will deploy a command backbone for

all type of access, and thus to reduce capital and operating cost.

New applications will be developed in an all-IP environment, whichguarantees optimal synergy between the mobile network and Internet.

GSM GPRSUMTSR99

UMTSR00

UMTSR4

UMTS

R5

(CS domain)

(IMS on top of

PS domain)

2G 2.5G 3G


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All-IP Architecture

Option 1

Support PS-domain multimedia and data service.

Option 2 Extend option 1 network by accommodating CS-

domain voice service over a packet switched core

network.


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All-IP Architecture (option 1)


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Radio Network Can be GERAN or UTRAN.

Home Subscriber Server Act as master database containing all 3G user-related subscriber

data.

GPRS Network Support mobility management and session management.

IP Multimedia Core Network Subsystem Provide mobility management and session management.

Application and Service Networks Support flexible services through service plateform.


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Call Session Control Function (CSCF)

Function

Communicate with HSS for location information

Handle control-layer functions related to application level

registration and SIP-based multimedia session.

Logical components Incoming Call Gateway

Communicate with HSS to

perform routing of incoming calls.

Call Control Function Handle call setup and call-event

report for billing and auditing.


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CSCF (cont.) Serving Profile Database

Interact with HSS in the home network to obtain profile information.

Address Handing Analyze, translate, and may modify address.

Three types of CSCF P-CSCF

Be assigned to a UE while it attaches to the network.

Forward the requests to the I-CSCF at home network.

I-CSCF Contact point for the home network of the destination UE.

Route the request towards the S-CSCF.

S-CSCF Be assigned to a UE after successful application level registration.

Support signing interactions with the UE for call setup andsupplementary services control.


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HSS, BGCF, and MGCF

Home Subscriber Server (HSS) Keep a list of features and services associated with users, and

maintain the location of the users.

Provide the HLR functionality required by the PC and CS domain,

and the IM functionality required by the IMS.

Breakout Gateway Control Function (BGCF) Select appropriate PSTN breakout point

(another BGCF or an MGCF).

Media Gateway ControlFunction (MGCF) Acts as the media gateway controller in

a VoIP network.

Control the media channels in an MGW.


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T-SGW, MRF, and MGW

Transport Signaling Gateway Function (T-SGW) Map call related signing from/to the PSTN on an IP bearer and

send it to/from the MGCF.

Media Resource Function (MRF)

Perform multiparty call, multimedia conference, tones and announcementsfunctionalities.

Media Gateway (MGW)

Provide user plane data transport between

UMTS core network and PSTN.

Interact with MGCF for resource

control.


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Two control elements are introduced: MSC server and GMSC server.

Support Media Gateway Control Protocol (MGCP) or H.248 to handle

control layer functions related to CS domain.

MSC server + MGW = MSC (in UMTS R99)

Control plane

User plane

A i i i i


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Application Level Registration

Step 1. UE sends SIP REGISTER to

P-CSCF.Step 2. P-CSCF performs address

translation of UEs home domain

name to find I-CSCF address.

Step 3. I-CSCF determines the HSS

address, and queries the HSS about

the registration status of the UE.

Step 4. I-CSCF obtains the required

S-CSCF capability information and

selects an appropriate S-CSCF.

Step 5. I-CSCF forwards SIP

REGISTER to S-CSCF.

Step 6. S-CSCF presents its name an

subscriber identity to HSS.Step 7. S-CSCF obtains the UEs

subscriber data from HSS.

Step 8. SIP 200 OK is replied.

Step 9. P-CSCF stores the home

Documents

All IP Mobile