2G Cellular Data Networks

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Dr. Martin Land Hadassah College Spring 2010

2G Cellular

Data Networks

General Mobility Issues

Registration and Authentication

User

Locate local service provider access point Obtain network access

Service provider

Locate mobile user within network for MS-terminated connections Authenticate user access rights

Handoff

Users move between service access points

Service maintained when changing attachment point (location)

Roaming

Handoff between service providers Elaborate authentication and accounting

Wireless Communication data on cellular systems

3 Dr. Martin Land Hadassah College Spring 2010

Standard IP

User

Connects to IP router by LAN or point-to-point connection

Sends IP datagrams containing source and destination IP addresses Receives IP datagrams to (possibly temporary) dedicated IP address

IP address = network number.host number Router

Forwards datagram to next hop according to routing protocol Routing tables locate host by NETWORK NUMBER

Router 132.4.16.X X=1, 2, 3, ..., 254 1 2 3 Router 138.27.192.Y Y=1, 2, 3, ..., 254 1 2 3 _{138.27.192.87} Wireless Communication data on cellular systems

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Dr. Martin Land Hadassah College

Spring 2010

Mobile IP (RFC 2002)

Internet protocol supporting host mobility

Maintains TCP connections as host changes location Supports authentication

Mobile host maintains single long-term IP address

Version 4 IP address and address format are unaffected

Routing tunnel replaces standard IP routing

Router 132.4.16.X X=1, 2, 3, ..., 254 1 2 3 Router 138.27.192.Y Y=1, 2, 3, ..., 254 1 2 3 138.27.192.87

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Spring 2010

Mobile IP ⎯ Basic Idea

Similar to Call forwarding Mail forwarding at post office Mobile Node Permanent IP address

Usual home service router

Finds mobile service routers when roaming

Home router and mobile service router coordinate IP datagrams

Sent to usual home router

Forwarded by home router to mobile service router Forwarded to Mobile Node

IP datagram IP datagram IP datagram Dr. Martin Land Hadassah College Spring 2010

Mobile IP Entities

Mobile Node (MN)

Host or router that can change its point of attachment

Home Address

Permanent IP address assigned to MN

Correspondent Node (CN)

Node that sends datagrams to MN home address

Home Agent (HA)

Maintains table of registered mobile nodes Forwards datagrams addressed to mobile node

Foreign Agent (FA)

Delivers datagrams between MN and HA

Mobility Agent

HA or FA supporting mobility

Care-of-Address (COA)

FA address used to identify current location of MN

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Spring 2010

Mobile IP Service Definitions

Principle Connection Services

Agent Discovery

Care-of-Address Discovery Registration

Principle Delivery Services

Encapsulation Tunneling Decapsulation

Roaming and Handoff

Change of Foreign Agent Route Optimization

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Agent Discovery

Mobility Agents broadcast availability

Home Agents (HA) Foreign Agents (FA)

Mobile Node (MN) looks for

Local router services when connected to home network

Foreign Agent (FA) services when connected to foreign network

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Spring 2010

Care-of-Address Discovery

Mobile Node (MN)

Requests service from Foreign Agent (FA)

Foreign Agent

Assigns Care-of-Address (COA) to MN FA can have 1 or more available COAs Usually FA assigns same COA to all MNs

MN requests

service from FA

Registration

Foreign Agent

Requests Mobile IP support from MN’s Home Agent

Home Agent

Agrees to provide Mobile IP support

MN

Registers COA with its HA

HA forwards datagrams to FA

Datagrams for MN arrive at HA

MN registers

with FA and HA request to HAFA forwards

HA accepts or rejects FA informs

MN of status

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Establishment of Service in Mobile IP

MN in home network

MN in foreign network

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Spring 2010

Principle Delivery Services

Encapsulation

Enclose IP datagram inside second IP datagram Inner IP header: addressed from CN to MN Outer IP header: addressed from HA to COA

Tunneling

Path taken by encapsulated datagram From HA to FA

Decapsulation

FA opens encapsulated datagram FA forwards original datagram to MN

FA to MN forwarding works at DATA LINK LAYER

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Spring 2010

Mobile IP End-to-End Delivery

Standard IP datagram From: CNIP address

To: MNHome Address DATA Encapsulated

IP datagram From:HAIP address

To: FA COAAddress

From:CNIP address

To: MNHome Address DATA

Standard IP datagram

From:CNIP address

To: MNHome Address DATA

CN MN FA HA Dr. Martin Land Hadassah College Spring 2010

Roaming and Hand-Off

Roaming MN

Moves to new attachment point (network) Requires change of FA

Multiple bindings

Multiple COAs — old + new Avoid datagram loss

Avoid too frequent registrations

HA

Forwards each packet to multiple COAs

MN

Receives packet at one COA

Route optimization after reconnection

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Spring 2010

Change of Foreign Agent

CN HA FAold FAnew MN IP datagram EncapsulatedIP datagram _datagramIP MN changes location registration registration update ACK Encapsulated IP datagram IP datagram EncapsulatedIP datagram IP datagram IP datagram IP datagram ACK Encapsulated IP datagram Wireless Communication data on cellular systems

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Triangle Routing

Home agent is bottleneck

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Route Optimization

(1 ) IP da ta gr am IP datagrams (2_b) W ar nin g (3 ) Bin din g R eq ues t (4 ) Bin din g U pd ate (5) IP dat_ag ram HA FA (2a) Encapsulated IP datagram Dr. Martin Land Hadassah College Spring 2010

Roaming Under Route Optimization

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Spring 2010

Voice/Data Interfaces in Cellular Network

Public Switched Telephone Network

(PSTN)

Frame Relay, ATM, IP

Circuit Mode Packet Mode

Serial Data on Analog Modem

Analog Local Loop 300 - 3300 Hz Voice on Analog

Telephone

Voice on Digital Telephone

Digital Local Loop (ISDN) 64 kbps (DS-0)

Serial Data on ISDN

Network provides dedicated point-to-point SVC connections and charges for time and distance of connection

Network provides packet forwarding over one-to-many SVC connections and charges for packet volume Voice on AMPS Serial Data on Analog AMPS Modem T1/E1 Digital Concentrator Voice on TDMA, GSM, CDMA Serial Data in Digital Frame T1/E1 Digital Concentrator Packet Data in CDPD/GPRS/EDGE Frame Packet Data Frame Relay, ATM, IP Frame Relay, ATM, IP Wireless Communication data on cellular systems

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Data over AMPS

digital bits modem modulated (analog) data AMPS Network analog channels (300 - 3300 Hz) digital bits modem modulated (analog) data POTS Network analog channels (300 - 3300 Hz) modem digital bits PSTN

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Spring 2010

Cellular Circuit Mode Data Services

digital bits POTS Network analog channel (300 - 3300 Hz) modem digital bits digital bits modem ISDN digital channel (64 kbps) digital bits PSTN Cellular Network digital voice/data circuit mode channels

(9.6 - 19.2 kbps)

Spring 2010

Cellular Packet Mode Data Services

Internet IP Datagrams IP Datagrams Cellular Network

digital voice/data circuit mode channels and

packet mode datagram forwarding

(19.2 kbps - 2 Mbps)

Cellular service provider acts directly as ISP AMPS: CDPD

GSM: GPRS / EDGE

IP Datagrams

ISP User makes dial-up call to Internet Service Provider (ISP)

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Spring 2010

Cellular Data Terminals

Laptop using cellular phone as modem

Laptop with integrated cellular modem

Smartphone

with integrated cellular modem

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Spring 2010

wWAN Services for Cellular Technology

d-AMPS (IS-136)

Circuit mode data over voice channel Cellular Digital Packet Data (CDPD) End-of-life

GSM

Native circuit mode data channel General Packet Radio Service (GPRS)

Enhanced Data Rates for GSM Evolution (EDGE) Evolution path — 3G

CDMA

Circuit mode data over voice channel IS-95B

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Spring 2010

Cellular Digital Packet Data (CDPD)

Packet Mode data on AMPS frequencies

Shares radio frequency channels with voice calls AMPS and d-AMPS compatible

First service 1993

Considered 2.5G enhancement

Infrastructure additions to AMPS technology

Data channel equipment in cellular network Internal or external modem in mobile station

IP routing

Exchange standard IP datagrams with Internet Internal CDPD network

Implements Mobile IP to tunnel IP datagrams

Full duplex transmission up to 19.2 kbps

CDPD Network Architecture

Base System (BS) Base Transceiver Site (BTS) BTS Base Station Controller (BSC) Mobile Switching Center (MSC) PLMN BSS BS

Base Station Subsystem Public Land Mobile Network

Internet (IS) MD-IS PSTN MDBS M-ES F-ES Internal CDPD IP Tunneling Standard IP Routing CELL CLUSTER M-ES Wireless Communication data on cellular systems

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CDPD System Architecture Elements

Mobile End Station (M-ES)

Mobile Data Base Station (MDBS)

Data forwarding function in Base Transceiver Site (BTS)

Intermediate Station (IS)

Standard IP network routers, switches, gateways

Mobile Data Intermediate Station (MD-IS)

Data forwarding function in Mobile Switching Center (MSC)

Fixed End System (F-ES)

M-ES MDBS MD-IS IS F-ES

F-ES upstream radio downstream radio IS M-ES MDBS IS MD-IS IS Wireless Communication data on cellular systems

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Spring 2010

Mobile Data Base Station (MDBS)

Data forwarding function in Base Transceiver Site (BTS)

Manages data streams for all M-ESs in one cell Transmits and receives digital data in AMPS channels

Forward channel

Announces channel availability to CDPD M-ES MDBS transmits data to all M-ES

Provides ACK or NACK responses to M-ES packets

Reverse direction

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Spring 2010

Mobile Data Intermediate Stations (MD-IS)

Located in Mobile Switching Center (MSC)

Manages interface between CDPD and Internet Handles

TCP/IP to CDPD protocol conversion Mobility Management using Mobile IP

Protects upstream elements from mobility issues

Mobility management

MD-ISs exchange location information about roamers

Mobile Network Location Protocol (MNLP)

Home MD-IS

Default gateway for M-ES at home Home Agent (HA) for roaming M-ES

Attached MD-IS

Foreign Agent (FA) for roaming M-ES

CDPD Protocol Layers

TCP IP SNDCP MDLP MAC Physical (Radio) Data Link Network MDLP MAC Physical (Radio) IP IP

Data Link Data Link Physical Physical MDLP TCP IP Data Link Physical IP SNDCP MDLP TCP IP Data Link Physical Tunnel IP Networking TCP End-to-End Transport M-ES MDBS IS MD-IS IS Physical Data Link IP Physical Data Link IP Physical Data Link IP F-ES CDPD Internet

End-to-end transport of TCP segments

Internet hops perform standard IP datagram routing and forwarding CDPD hops implement Mobile IP

MD-IS performs tunneling to M-ES

MD-IS to MDBS to M-ES routing by IP address + phone number

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Physical Medium Access

Transmits over AMPS analog frequency channels Transfers data packets on unused voice channels

Unused AMPS frequencies or d-AMPS time slots

Sniff and hop

Base stations broadcast advertise available channels Mobile station listens for idle channels

Works well with excess network capacity

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MAC Protocol ⎯ Access Control in CDPD

Digital Sense Multiple Access/Collision Detect (DSMA/CD)

Contention-based access among CDPD M-ESs Exploits forward/reverse frequency pairing

Device senses the transmit medium

Listens for Idle flag in forward channel

If medium is Idle

Device sends data in reverse channel

Waits for ACK from MDBS in forward channel

Collision ⎯ transmission from multiple sources

MDBS returns Decode Failure flag

Random back-off period before trying again

Maximum transmit time of about 1 second per transmission f3: idle flag

f₁: busy flag f2: voice f4: packet data

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Spring 2010

Special CDPD Protocols

SNDCP ⎯ Subnetwork Dependent Convergence Protocol

Maps user IP datagrams to an MDLP channel Session services

SAR (Segmentation and Reassembly) M-ES uses SNDCP as tunnel to MD-IS

MDLP ⎯ Mobile Data Link Protocol

Framing

Destination addressing

Encrypted IP address used as MAC layer address

Logical Link Control (LLC) functions

Error control and flow control

CDPD MAC ⎯ DSMA-CD

Manages channel access

Manages collision detection and packet retry process

Spring 2010

M-ES in Home System

F-ES places TCP segment into IP datagram addressed to M-ES

Network Entity Identifier (NEI)

Standard IP address for M-ES Assigned by CDPD service provider

IP datagram routed through Internet to Home MD-IS Home MD-IS tunnels IP datagram to M-ES via MDBS

SNDCP

Opens ports to M-ES for session service Encrypts IP datagram

Encrypted form of NEI is Temporary Equipment Identifier (TEI) Performs SAR (Segmentation and Reassembly)

Passes segments to MDLP

MDLP

Builds data link frame Addressed to TEI

Includes frame sequencing, flow control, and error control fields Passes MDLP frame to TCP/IP for transmission to MDBS

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Mobility and Tunneling

Entire CDPD system is one Internet domain

Controlled by one MD-IS Acts as an Internet subnet

End-to-end tunnel (SNDCP and MDLP over TCP/IP) covers service area TEI in MDLP packets permits mobile MAC-layer addressing

Telephone number permits mobile physical layer addressing

Base Station Controller (BSC) Mobile Switching Center (MSC) Internet (IS) MD-IS MDBS M-ES F-ES Internal CDPD IP Tunneling St a n da rd IP Ro u tin g IS Wireless Communication data on cellular systems

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Spring 2010

Mobility and Tunneling

Handoff

M-ES moves between cells or between clusters End-to-end tunnel still covers service area

MDLP frames forwarded to new MDBS within TCP/IP frames

Mobility handled by telephone mobility MDLP frames still addressed to same TEI

Base Station Controller (BSC) Mobile Switching Center (MSC) Internet (IS) MD-IS MDBS M-ES F-ES Internal CDPD IP Tunneling St a n da rd IP Ro u tin g IS ha nd off

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Spring 2010

Roaming M-ES

M-ES

Connects to network in non-home system Registers with local (attachment) MD-IS Attachment MD-IS

Exchanges location data with Home MD-IS

Mobile Network Location Protocol (MNLP)

Assigns roamer Subnetwork Point of Attachment (SNPA) address Functions as Mobile IP Foreign Agent (FA)

Home MD-IS

Functions as Mobile IP Home Agent (HA) F-ES

Addresses TCP segment to M-ES NEI IP datagram

Routed through Internet to Home MD-IS

Home MD-IS tunnels to attachment MD-IS using SNPA

Attachment MD-IS tunnels IP datagram to M-ES via MDBS, SNDCP, MDLP

Spring 2010

Mobile Station and Fixed Station

M-ES MDBS IS MD-IS IS F-ES MDBS IS MD-IS IS Home M-ES M-ES Subdomain Subdomain 1 2 3 4 5 Wireless Communication data on cellular systems

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M-ES in Roaming Subdomain and F-ES

M-ES MDBS IS MD-IS IS F-ES MDBS IS MD-IS IS M-ES Roaming M-ES Subdomain Subdomain 1 2 3 4 5 1 2 3 4 5 6 7 8 Wireless Communication data on cellular systems

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M-ES in Home Subdomain with Roaming M-ES

Home M-ES MDBS IS MD-IS IS F-ES MDBS IS MD-IS IS M-ES Roaming M-ES Subdomain Subdomain 1 2 3 4 5 6 1 2 ₃ 4 5 6 7 8 9 10 11 12

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General Packet Radio Service (GPRS)

Provides packet mode data access for GSM

IP-based architecture

IP datagrams separated from circuit mode traffic at cluster

Packet Control Unit (PCU)

Packet mode function in BSC to handle IP datagrams

Circuit mode voice/data routed to MSC

Forwarded to other MSC or PSTN

Packet mode data is routed to Serving GPRS Support Node (SGSN)

Forwarded to Internet or X.25 PSDN PCU to SGSN runs IP over Frame Relay

Mobility management

Circuit mode traffic uses PSTN / PLMN routing Packet mode traffic uses IP routing

Spring 2010

GSM Circuit Mode and GPRS Packet Mode Data

GPRS System Architecture

Base System (BS) Base Transceiver Site (BTS) BTS Base Station Controller (BSC) Mobile Switching Center (MSC) PLMN BSS Base System (BS) MS

Base Station Subsystem

Public Land Mobile Network

Frame Relay Internet Serving GPRS Support Node (SGSN) Gateway GPRS Support Node (GGSN) PSTN Packet Control Unit (PCU) GPRS Backbone (IP) MS Wireless Communication data on cellular systems

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GPRS Support Nodes

Serving GPRS Support Node (SGSN)

Packet-switched version of MSC

Handles packets to / from Mobile Stations (MS) Handles MS mobility management

Gateway GPRS Support Node (GGSN)

Interfaces SGSNs to external IP networks Maintains routing information

Exterior gateway for GPRS network Address mapping (IP mobility)

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GPRS Terminal Classes

Class A terminal

Supports simultaneous GPRS and GSM voice services

Class B terminal

Supports GPRS or GSM voice service at one time

Monitor (on hold) one channel and operate second channel simultaneously

Class C terminal

Supports only one service at a time

Spring 2010

GPRS System Elements

Authentication Center AUC

Service Order Gateway SOG

Border Gateway BG

Call Detail Record CDR

Charging Gateway CG

Gateway GPRS Support Node GGSN

Serving GPRS Support Node SGSN

Base Station Subsystem BSS

Visitor Location Register VLR

Home Location Register HLR

Base Station Controller BSC

Base Transceiver Site BTS

GPRS System Architecture

BTS MSC BS Internet SGSN GGSN PSTN BSC _BackboneGPRS MS PLMN - 1 GGSN BTS MSC BS SGSN BSC MS BTS MSC BS SGSN BSC _BackboneGPRS MS PLMN - 2 GPRS Backbone Border Gateway Border Gateway

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Spring 2010

GPRS Architecture Protocol Stack

From Internet or X.25 MS to SGSN Tunnel SGSN to GSSN Tunnel MS to BSS Tunnel BSS to SGSN Tunnel Dr. Martin Land Hadassah College Spring 2010

GPRS Protocol Structure — 1

Fixed-system application sends data to MS

IP datagrams or X.25 packets Basic hops Internet → GGSN → SGSN → BSS → MS GGSN → SGSN L1 L1

Standard user IP datagrams from Internet IP GGSN SGSN L2 L2 IP IP

Standard TCP/IP and infrastructure protocols TCP/UDP

TCP/UDP

GPRS Tunneling Protocol (GTP)

GTP header added to user IP datagram Call Data Records (CDR) for billing Handles call failure

GTP GTP

GPRS Protocol Structure — 2

SGSN-to-MS Tunnel

Logical Link Control (LLC) LLC header

Flow control Error control Link control

Sub-Network Dependent Convergence Protocol (SNDCP)

SNDCP header

Encapsulates GTP + user IP datagrams Provides

Session services

SAR (Segmentation and Reassembly) Maps user IP datagrams to LLC channel

BSS SGSN L1bis NW BSSGP LLC SNDCP L1 MS L2 IP TCP/ UDP LLC GTP SNDCP Wireless Communication data on cellular systems

GPRS Protocol Structure — 3

SGSN to BSS

Frame Relay packets

Maps BSSGP signaling to Frame Relay signaling Map LLC packets to BSSGP

Base Station System GPRS Protocol (BSSGP)

Processes routing and QoS information Routing layer for Frame Relay signaling Call setup / control signaling over Frame Relay

SGSN L1bis NW BSSGP LLC SNDCP L1 L1bis BSS L2 NW IP BSSGP TCP/ UDP GTP

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GPRS Protocol Structure — 4

BSS to MS GSM Radio Frequency (RF) MS allocated 1 to 8 GSM time slots

18 kbps per time slot ⇒ 18 kbps to 144 kbps Media Access Control (MAC)

Between MS and BSS Controls access to GPRS Radio Link Control (RLC)

MS-to-BSS Logical Link Control Flow control, error control, link control BSSGP RF MAC RLC BSS RF MAC LLC RF MS MAC RLC SNDCP IP Dr. Martin Land Hadassah College Spring 2010

GPRS Connection Process

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Spring 2010

GPRS Connection Process

MS switches on and sends GPRS attach request User Registration — 1

Associate PLMN address with Packet Data Protocol (PDP) address

PDP address — Static or dynamic IP or X.25 address PLMN address — International Mobile Subscriber ID (IMSI)

Authentication

BSC queries Home Location Registers (HLR) — 2 HLR updates Visitor Location Registers (VLR) — 3

Call Admission Control (CAC) — 4

Determines required network resources Grants resources if available

Routing — hop-by-hop IP datagram or X.25-PLP delivery

Routing tables in GSN (GGSN or SGSN)

Address conversion / VC mapping

GSN handles compression and encryption

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Enhanced Data Rates for GSM Evolution (EDGE)

Standard: GPRS-136HS

Formally defined as 3G enhancement to GPRS

Uses enhanced modulation technique Transmits 60 kbps in each time slot 8 slots × 60 kbps/slot = 480 kbps Uses 384 kbps for user data

Planned (but not relevant)

CDPD Gateway

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Spring 2010

Short Message Service (SMS)

Transmission of short text messages

Up to 160 bytes of alphanumeric data

160 English ASCII characters

16-bit unicode for non-English alphabets ⇒ 80 characters

GSM permits message concatenation

Supported by GSM, d-AMPS, and CDMA Out-of-band signaling

SMS sent over signaling channel — not traffic channel SMS can be sent during a voice call

Short messages do not create a heavy traffic load

SMS in GSM Architecture

GMSC SMSC IWMSC SME SMSC

SME: Short Messaging Entity

SMSC: Short Message Service Center GMSC: Gateway Message Service Center

IWMSC: Interworking Message Service Center

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SMS Nodes

Short Messaging Entity (SME)

Any entity that can receive or send short messages

Fixed network element Mobile Station

Another service center

Short Message Service Center (SMSC)

Store and forwarding of SMS between SME and MS

Gateway Message Service Center (GMSC)

Receives SMS from SMSC

Interrogates HLR for routing information Delivers SMS to MSC for destination SME

Interworking Message Service Center (IWMSC)

Receives SMS from MSC

Delivers SMS to appropriate SMSC for forwarding

SMS Delivery to MS

SME SMSC HLR MSC VLR BSS SMS Submit _Route Request Route SMS Forward MS User Info ACK User Info Page ACK ACK SMS Forward SMS Forward ACK ACK Delivery Report Delivery Report

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Spring 2010

High Speed Circuit Switched Data (HSCSD)

Circuit Switched Data (CSD)

14.4 kbps circuit mode data connection in 2G GSM User data replaces digitized voice in 1 time slot

High Speed Circuit Switched Data (HSCSD)

2.5G enhancement

Up to 8 slots (full user frame) allocated to one data channel Up to 115.2 kbps

Transparent data transmission

User data stream can contain signaling to network

Allows dynamic reconfiguration of data connection (data rate, QoS)

HSCSD data frames carry data sub-stream numbers

Maintains order of transmission over GSM

Non-transparent data transmission

Only user data in data stream

No signaling or reconfiguration

LLC functions performed by GSM protocols

Spring 2010

2.5G Cellular Video

Video conferencing

MS-to-MS or MS-to-PC audio / video connection Video conference

Technology demonstrated in 1926 Commercial systems available since 1964

AT&T lost $250 million (in 1965 dollars) on Picture Phone

Personal feel of cellular call may overcome customer resistance

Live video streaming

TV broadcasting to telephones Video-on-Demand (VOD)

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Protocol Options for Digital Video

Digital multimedia streaming options for fixed terminals

Circuit-switched technology

Compressed video over 64 kbps ISDN

High quality video over B-ISDN (ATM-based) networks Used by corporate networks and news reporting Not widely adopted by home users

Packet-switched technology

IP based

H.323 protocol for video call (also used in Voice Over IP) Widely implemented

Digital multimedia streaming options for mobile terminals

Packet-switched technology

Video over H.323 over cellular IP (GPRS/EDGE/UTMS)

Circuit-switched technology

Compressed video over High Speed Circuit Switched Data (HSCSD)

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Protocol Options for Cellular Digital Video

Cellular IP

Fine for non-real-time services with bursty data

Web browsing SMS/MMS

Cannot provide QoS required for non-bursty video

Low transmission delay and jitter

Traffic and mobility variations make delay highly variable

HSCSD provides

Dedicated channel with no delay variation High availability

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Spring 2010

3G-324M Protocol for Video

Defines required services for multimedia calls

Call set-up Call routing Frame structure Frame multiplexing

Voice and image coordination Call security

Specifies profiles for existing standards

H.223 Multiplexing and De-multiplexing H.245 Call Control H.263 Video Codec Dr. Martin Land Hadassah College Spring 2010

3G-324M Functions

H.223 Multiplexing Protocol

Divides the HSCSD channel into subchannels

Assigns subchannels to voice, audio, control, and data Segmentation and Reassembly (SAR)

Provides low delay and low overhead

Determines procedures depending on system error rate

H.245 Control Protocol

Procedures for setting up and controlling video calls Control message definitions and structures

Error control and flow control for digital video packets

H.263 Video Coding

Encoding procedures for video channels Mandates widely used standard codecs Permits optional codecs such as MPEG-4

3G-324M System Architecture

Call Signaling Dialing number Call acceptance

Establishing bearer channel

Multiplexer and Demultiplexer (H.223) HSCSD Transparent 64 kbps synchronous link Video Codec Audio Codec Call Control (H.245) Camera Screen Microphone Speaker Operating System Call Control

Exchange terminal capabilities Determine session master Open audio and video logical