GSM & GPRS

Communication Networks Winter 2014/15

Prof. Jochen Seitz 1

Communication Networks

Chapter 8. GSM and GPRS

o GSM Architecture and Protocols

o Data Services in GSM

o General Packet Radio Service GPRS

o The Wireless Application Protocol

Mobile Phone Subscribers

Worldwide

Communication Networks - 8: GSM & GPRS 298

year

Su

bscri

bers

[m

illio

n]

0

200

400

600

800

1000

1200

1400

1600

1996 1997 1998 1999 2000 2001 2002 2003 2004

approx. 1.7 bn

GSM total

TDMA total

CDMA total

PDC total

Analogue total

W-CDMA

Total wireless

Prediction (1998) 2009:

>4 bn!




GSM Subscribers by Region

GSM: Overview

GSM

formerly: Groupe Spciale Mobile (founded 1982)

now: Global System for Mobile Communication

Pan-European standard (ETSI, European Telecommunications Standardisation Institute)

simultaneous introduction of essential services in three phases (1991, 1994, 1996) by the European telecommunication administrations (Germany: D1 and D2) seamless roaming within Europe possible

Today many providers all over the world use GSM(219 countries in Asia, Africa, Europe, Australia, America)

more than 4,2 billion subscribers in more than 700 networks

more than 75% of all digital mobile phones use GSM

over 29 billion SMS in Germany in 2008, (> 10% of the revenues for many operators) [be aware: these are only rough numbers]

See e.g. www.gsmworld.com/newsroom/market-data/index.htm




Performance Characteristics of GSM

Communication

mobile, wireless communication; support for voice and data services

Total mobility

international access, chip-card enables use of access points of different providers

Worldwide connectivity

one number, the network handles localization

High capacity

better frequency efficiency, smaller cells, more customers per cell

High transmission quality

high audio quality and reliability for wireless, uninterrupted phone calls at higher speeds (e.g., from cars, trains)

Security functions

access control, authentication via chip-card and PIN


Disadvantages of GSM

There is no perfect system!! no end-to-end encryption of user data no full ISDN bandwidth of 64 kbit/s to the user, no

transparent B-channel

reduced concentration while driving

electromagnetic radiation

abuse of private data possible

roaming profiles accessible

high complexity of the system

several incompatibilities within the GSM standards




GSM: Mobile Services

GSM offers

several types of connections voice connections, data connections, short message service

multi-service options (combination of basic services)

Three service domains

Bearer Services Telematic Services Supplementary Services


GSM-PLMNGSM-PLMN

transit

network

(PSTN, ISDN)

transit

network

(PSTN, ISDN)

source/

destination

network

source/

destination

network

TETE TETE

bearer services

tele services

R, S (U, S, R)Um

MTMT

MS

Bearer Services

Telecommunication services to transfer data between access points

Specification of services up to the terminal interface (OSI layers 1-3)

Different data rates for voice and data (original standard)

data service (circuit switched) synchronous: 2.4, 4.8 or 9.6 kbit/s asynchronous: 300 - 1200 bit/s

data service (packet switched) synchronous: 2.4, 4.8 or 9.6 kbit/s asynchronous: 300 - 9600 bit/s

Today: data rates of approx. 50 kbit/s possible will be covered later! (even more with new modulation)




Tele Services I

Telecommunication services that enable voice

communication via mobile phones

All these basic services have to obey cellular functions,

security measurements etc.

Offered services

Mobile telephonyprimary goal of GSM was to enable mobile telephony offering

the traditional bandwidth of 3.1 kHz

Emergency numbercommon number throughout Europe (112); mandatory for all

service providers; free of charge; connection with the highest

priority (preemption of other connections possible)

Multinumberingseveral phone numbers per user possible


Tele Services II

Additional services

Non-Voice-Teleservices

group 3 fax

voice mailbox (implemented in the fixed network supporting the mobile terminals)

electronic mail (MHS, Message Handling System, implemented in the fixed network)

...

Short Message Service (SMS)alphanumeric data transmission to/from the mobile terminal (160

characters) using the signaling channel, thus allowing simultaneous

use of basic services and SMS

(almost ignored in the beginning now the most successful add-on!)




Supplementary Services

Services in addition to the basic services, cannot be offered stand-alone

Similar to ISDN services besides lower bandwidth due to the radio link

May differ between different service providers, countries and protocol versions

Important services identification: forwarding of caller number suppression of number forwarding automatic call-back conferencing with up to 7 participants locking of the mobile terminal (incoming or outgoing calls) ...


Architecture of the GSM System

GSM is a PLMN (Public Land Mobile Network)

several providers setup mobile networks following the GSM standard within each country

components MS (mobile station)

BS (base station)

MSC (mobile switching center)

LR (location register)

subsystems RSS (radio subsystem): covers all radio aspects

NSS (network and switching subsystem): call forwarding, handover, switching

OSS (operation subsystem): management of the network




Ingredients 1: Mobile Phones, PDAs

& Co.


The visible but smallest

part of the network!

Ingredients 2: Antennas

Communication Networks - 8: GSM & GPRS

Still visible cause many discussions310



Ingredients 3: Infrastructure 1


Base Stations

Cabling

Microwave links

311

Ingredients 3: Infrastructure 2


Switching units

Data bases

Management

Monitoring

Not visible, but

comprise the major part

of the network (also from

an investment point of

view)



GSM: Overview


fixed network

BSC

BSC

MSC MSC

GMSC

OMC, EIR,

AUC

VLR

HLRNSS

with

OSS

RSS

VLR

GSM: Elements and Interfaces


NSS

MS MS

BTS

BSC

GMSC

IWF

OMC

BTS

BSC

MSC MSC

Abis

Um

EIR

HLR

VLR VLR

A

BSS

PDN

ISDN, PSTN

RSS

radio cell

radio cell

MS

AUCOSS

signaling

O



GSM: System Architecture


Um

Abis

ABSS

radio

subsystem

MS MS

BTS

BSCBTS

BTS

BSCBTS

network and switching

subsystem

MSC

MSC

fixed

partner networks

IWF

ISDN

PSTN

PSPDN

CSPDN

SS7

EIR

HLR

VLR

ISDN

PSTN

System Architecture:

Radio Subsystem Components

MS (Mobile Station)

BSS (Base Station Subsystem):consisting of

BTS (Base Transceiver Station):sender and receiver

BSC (Base Station Controller):controlling several transceivers

Interfaces

Um : radio interface

Abis : standardized, open interface with16 kbit/s user channels

A: standardized, open interface with 64 kbit/s user channels


Um

Abis

A

BSS

radio

subsystem

network and switching

subsystem

MS MS

BTS

BSC MSCBTS

BTS

BSCBTS

MSC



System Architecture: Network and

Switching Subsystem Components

MSC (Mobile Services Switching Center)

IWF (Interworking Functions)

ISDN (Integrated Services Digital Network)

PSTN (Public Switched Telephone Network)

PSPDN (Packet Switched Public Data Network)

CSPDN (Circuit Switched Public Data Network)

Databases HLR (Home Location Register)

VLR (Visitor Location Register)

EIR (Equipment Identity Register)


network

subsystem

MSC

MSC

fixed partner

networks

IWF

ISDN

PSTN

PSPDN

CSPDN

SS7

EIR

HLR

VLR

ISDN

PSTN

Radio Subsystem

The Radio Subsystem (RSS) comprises the cellular

mobile network up to the switching centers

Components

Base Station Subsystem (BSS):

Base Transceiver Station (BTS): radio components including sender,

receiver, antenna - if directed antennas are used one BTS can

cover several cells

Base Station Controller (BSC): switching between BTSs, controlling

BTSs, managing of network resources, mapping of radio channels

(Um) onto terrestrial channels (A interface)

BSS = BSC + sum(BTS) + interconnection

Mobile Stations (MS)




GSM: Cellular Network

use of several carrier frequencies

not the same frequency in adjoining cells

cell sizes vary from some 100 m up to 35 km depending on user density, geography, transceiver power etc.

hexagonal shape of cells is idealized (cells overlap, shapes depend on geography)

if a mobile user changes cells, handover of the connection to the neighbor cell


possible radio coverage of the cell

idealized shape of the cellcell

segmentation of the area into cells

319

GSM Frequency Bands (Examples)


Type Channels Uplink [MHz] Downlink [MHz]

GSM 850 128-251 824-849 869-894

GSM 900

classical

extended

0-124, 955-1023

124 channels

+49 channels

876-915

890-915

880-915

921-960

935-960

925-960

GSM 1800 512-885 1710-1785 1805-1880

GSM 1900 512-810 1850-1910 1930-1990

GSM-R

exclusive

955-1024, 0-124

69 channels

876-915

876-880

921-960

921-925

- Additionally: GSM 400 (also named GSM 450 or GSM 480 at 450-458/460-468 or 479-486/489-496 MHz)

- Please note: frequency ranges may vary depending on the country!

- Channels at the lower/upper edge of a frequency band are typically not used



Example Coverage of GSM

Networks (www.gsmworld.com)


T-Mobile (GSM-900/1800) Germany O2 (GSM-1800) Germany

AT&T (GSM-850/1900) USA Vodacom (GSM-900) South Africa


Coverage Close to Ilmenau

(www.gsmworld.com)

e-plus (GSM-1800)

D1 (GSM-900) around Ilmenau

O2

(GSM-1800)

Vodafone D2

(GSM-900)



Base Transceiver Station and

Base Station Controller Tasks of a BSS are distributed over BSC and BTS

BTS comprises radio specific functions

BSC is the switching center for radio channels


Functions BTS BSC

Management of radio channels X

Frequency hopping (FH) X X

Management of terrestrial channels X

Mapping of terrestrial onto radio channels X

Channel coding and decoding X

Rate adaptation X

Encryption and decryption X X

Paging X X

Uplink signal measurements X

Traffic measurement X

Authentication X

Location registry, location update X

Handover management X

Mobile Station

Terminal for the use of GSM services

A mobile station (MS) comprises several functional groups

MT (Mobile Terminal): offers common functions used by all services the MS offers corresponds to the network termination (NT) of an ISDN access end-point of the radio interface (Um)

TA (Terminal Adapter): terminal adaptation, hides radio specific characteristics

TE (Terminal Equipment): peripheral device of the MS, offers services to a user does not contain GSM specific functions

SIM (Subscriber Identity Module): personalization of the mobile terminal, stores user parameters


R SUm

TE TA MT



Network and Switching Subsystem

NSS is the main component of the public mobile network GSM

switching, mobility management, interconnection to other networks, system control

Components

Mobile Services Switching Center (MSC)controls all connections via a separated network to/from a mobile terminal within the domain of the MSC - several BSC can belong to a MSC

Databases (important: scalability, high capacity, low delay) Home Location Register (HLR)

central master database containing user data, permanent and semi-permanent data of all subscribers assigned to the HLR (one provider can have several HLRs)

Visitor Location Register (VLR)local database for a subset of user data, including data about all user currently in the domain of the VLR


Mobile Services Switching Center

The MSC (mobile services switching center) plays a central role in GSM

switching functions

additional functions for mobility support

management of network resources

interworking functions via Gateway MSC (GMSC)

integration of several databases

Functions of a MSC

specific functions for paging and call forwarding

termination of SS7 (signaling system no. 7)

mobility specific signaling

location registration and forwarding of location information

provision of new services (fax, data calls)

support of short message service (SMS)

generation and forwarding of accounting and billing information




Operation Subsystem

The OSS (Operation Subsystem) enables centralized operation, management, and maintenance of all GSM subsystems

Components Authentication Center (AUC)

generates user specific authentication parameters on request of a VLR

authentication parameters used for authentication of mobile terminals and encryption of user data on the air interface within the GSM system

Equipment Identity Register (EIR) registers GSM mobile stations and user rights stolen or malfunctioning mobile stations can be locked and

sometimes even localized

Operation and Maintenance Center (OMC) different control capabilities for the radio subsystem and the

network subsystem


GSM - TDMA/FDMA


1 2 3 4 5 6 7 8

higher GSM frame structures

935-960 MHz

124 channels (200 kHz)

downlink

890-915 MHz

124 channels (200 kHz)

uplink

time

GSM TDMA frame

GSM time-slot (normal burst)

4.615 ms

546.5 s577 s

tail user data TrainingSguard

space S user data tailguard

space

3 bits 57 bits 26 bits 57 bits1 1 3



GSM Hierarchy of Frames


0 1 2 2045 2046 2047...

hyperframe

0 1 2 48 49 50...

0 1 24 25...

superframe

0 1 24 25...

0 1 2 48 49 50...

0 1 6 7...

multiframe

frame

burst

slot

577 s

4.615 ms

120 ms

235.4 ms

6.12 s

3 h 28 min 53.76 s

GSM Protocol Layers for Signaling


CM

MM

RR

MM

LAPDm

radio

LAPDm

radio

LAPD

PCM

RR BTSM

CM

LAPD

PCM

RR

BTSM

16/64 kbit/s

Um Abis A

SS7

PCM

SS7

PCM

64 kbit/s /

2.048 Mbit/s

MS BTS BSC MSC

BSSAPBSSAP



Mobile Terminated Call (MTC)

1: calling a GSM subscriber

2: forwarding call to GMSC

3: signal call setup to HLR

4, 5: request MSRN from VLR

6: forward responsible MSC to GMSC

7: forward call to

current MSC

8, 9: get current status of MS

10, 11: paging of MS

12, 13: MS answers

14, 15: security checks

16, 17: set up connection


PSTNcalling

stationGMSC

HLR VLR

BSSBSSBSS

MSC

MS

1 2

3

4

5

6

7

8 9

10

11 12

1316

10 10

11 11 11

14 15

17

Mobile Originated Call (MOC)

1, 2: connection request

3, 4: security check

5-8: check resources (free circuit)

9-10: set up call


PSTN GMSC

VLR

BSS

MSC

MS1

2

6 5

3 4

9

10

7 8



MTC/MOC


BTSMS

paging request

channel request

immediate assignment

paging response

authentication request

authentication response

ciphering command

ciphering complete

setup

call confirmed

assignment command

assignment complete

alerting

connect

connect acknowledge

data/speech exchange

BTSMS

channel request

immediate assignment

service request

authentication request

authentication response

ciphering command

ciphering complete

setup

call confirmed

assignment command

assignment complete

alerting

connect

connect acknowledge

data/speech exchange

MTC MOC

4 Types of Handover


MSC MSC

BSC BSCBSC

BTS BTS BTSBTS

MS MS MS MS

12 3 4



Handover Decision


receive level

BTSold

receive level

BTSold

MS MS

HO_MARGIN

BTSold BTSnew

Handover Procedure


HO access

BTSold BSCnew

measurement

result

BSCold

Link establishment

MSCMSmeasurement

report

HO decision

HO required

BTSnew

HO request

resource allocation

ch. activation

ch. activation ackHO request ackHO commandHO commandHO command

HO completeHO completeclear commandclear command

clear complete clear complete



Security in GSM

Security services

access control/authentication user SIM (Subscriber Identity Module): secret PIN (personal identification

number)

SIM network: challenge response method

confidentiality voice and signaling encrypted on the wireless link

(after successful authentication)

anonymity temporary identity TMSI

(Temporary Mobile Subscriber Identity)

newly assigned at each new location update (LUP)

encrypted transmission

3 algorithms specified in GSM

A3 for authentication (secret, open interface)

A5 for encryption (standardized)

A8 for key generation (secret, open interface)


secret:

A3 and A8 available

via the Internet

network providers

can use stronger

mechanisms

secret:

A3 and A8 available

via the Internet

network providers

can use stronger

mechanisms

GSM - Authentication


A3

RANDKi

128 bit 128 bit

SRES* 32 bit

A3

RAND Ki

128 bit 128 bit

SRES 32 bit

SRES* =? SRES SRES

RAND

SRES

32 bit

mobile network SIM

AC

MSC

SIM

Ki: individual subscriber authentication key SRES: signed response



GSM - Key Generation and

Encryption


A8

RANDKi

128 bit 128 bit

Kc64 bit

A8

RAND Ki

128 bit 128 bit

SRES

RAND

encrypted

data

mobile network (BTS) MS with SIM

AC

BSS

SIM

A5

Kc64 bit

A5

MSdata data

cipher

key

Data Services in GSM I

Data transmission standardized with only 9.6 kbit/s

advanced coding allows 14.4 kbit/s not enough for Internet and multimedia applications

HSCSD (High-Speed Circuit Switched Data)

mainly software update bundling of several time-slots to get higher AIUR (Air Interface

User Rate, e.g., 57.6 kbit/s using 4 slots @ 14.4)

advantage: ready to use, constant quality, simple disadvantage: channels blocked for voice transmission


AIUR [kbit/s] TCH/F4.8 TCH/F9.6 TCH/F14.4

4.8 1

9.6 2 1

14.4 3 1

19.2 4 2

28.8 3 2

38.4 4

43.2 3

57.6 4



Data Services in GSM II

GPRS (General Packet Radio Service)

packet switching

using free slots only if data packets ready to send (e.g., 50 kbit/s using 4 slots temporarily)

standardization 1998, introduction 2001

advantage: one step towards UMTS, more flexible

disadvantage: more investment needed (new hardware)

GPRS network elements

GSN (GPRS Support Nodes): GGSN and SGSN

GGSN (Gateway GSN) interworking unit between GPRS and PDN (Packet Data Network)

SGSN (Serving GSN) supports the MS (location, billing, security)

GR (GPRS Register) user addresses


GPRS Quality of Service


Reliability class Lost SDU probability

Duplicate SDU probability

Out of sequence SDU

probability

Corrupt SDU probability

1 10-9 10-9 10-9 10-9

2 10-4 10-5 10-5 10-6

3 10-2 10-5 10-5 10-2

Delay SDU size 128 byte SDU size 1024 byte

class mean 95 percentile mean 95 percentile

1 < 0.5 s < 1.5 s < 2 s < 7 s 2 < 5 s < 25 s < 15 s < 75 s

3 < 50 s < 250 s < 75 s < 375 s 4 unspecified



Examples for GPRS Device Classes


ClassReceiving

slotsSending slots Maximum number of slots

1 1 1 2

2 2 1 3

3 2 2 3

5 2 2 4

8 4 1 5

10 4 2 5

12 4 4 5

GPRS User Data Rates in kbit/s


Coding

scheme

1 slot 2 slots 3 slots 4 slots 5 slots 6 slots 7 slots 8 slots

CS-1 9.05 18.1 27.15 36.2 45.25 54.3 63.35 72.4

CS-2 13.4 26.8 40.2 53.6 67 80.4 93.8 107.2

CS-3 15.6 31.2 46.8 62.4 78 93.6 109.2 124.8

CS-4 21.4 42.8 64.2 85.6 107 128.4 149.8 171.2



GPRS Architecture and Interfaces


MS BSS GGSNSGSN

MSC

Um

EIR

HLR/

GR

VLR

PDN

Gb Gn Gi

SGSN

Gn


GPRS Protocol Architecture

Appl.

IP/X.25

LLC

GTP

MAC

Radio

MAC

RadioFR

RLC BSSGP

IP/X.25

FR

Um Gb Gn

L1/L2 L1/L2

MS BSS SGSN GGSN

UDP/TCP

Gi

SNDCP

RLC BSSGP IP IP

LLC UDP/TCP

SNDCP GTP




GPRS Session Management

MN registers with GPRS network:

GPRS-Attach to SGSN

MN receives Packet Temporary Mobile Subscriber

Identity P-TMSI

Then, MN gets a Packet Data Protocol Address (PDP-

Address), e.g. an IP-Address

Finally, the PDP context is created in MN, SGSN, GGSN:

PDP-Type (e.g. IPv4)

PDP-Address of MN (e.g. 129.187.222.10)

Desired Quality of Service (QoS Class)

GGSN address that serves as gateway to the external network


GPRS PDP Context Activation

MNMN SGSNSGSN GGSNGGSN

Security Functions



GPRS Location Management

Main task: retrieving the current location of a mobile subscriber

Periodical Location Update messages to SGSN special state model:


IDLEIDLE

READYREADY

STANDBYSTANDBY

GPRS

Attach

GPRS

Detach

Ready Timer expired

or Force to Standby

Packet

delivery

Standby Timer

expired


GPRS Intra-SGSN Routing Area

Update

MSMS BSSBSS SGSNSGSN

Security Functions




GPRS Inter-SGSN Routing Area

Update

Security Functions

MSMS BSSBSS New SGSNNew SGSN Old SGSNOld SGSN GGSNGGSN HLRHLR MSC/VLRMSC/VLR


HeaderHeader

HeaderHeader

GPRS Data Flow and Segmenting

HeaderHeader InformationInformation

SegmentSegment SegmentSegment

SegmentSegment FCSFCS

SegmentSegment SegmentSegment

SegmentSegment BCSBCS

...

...

IP-

Packet

SNDCP-

Layer

LLC Frame LLC-

Layer

RLC/MAC-

Block

RLC/MAC-

Layer




GPRS Routing and Address

Translation (I)

SGSN

SGSN

GGSNBSC

InternetIP Packet

(IP Source,

IP Destination)

1.) Address translation

according to PDP-

context:

IP-Destination TID+SGSN-Address


according to PDP-

context:

IP-Destination TID+SGSN-Address

GTP (SGSN-Address,

TID, IP Packet)


according to PDP-context:

TID TLLI + NSAPI (+CI)



TID TLLI + NSAPI (+CI)

SNDCP (TLLI,

NSAPI, IP Packet)

IP Packet


GPRS Routing and Address

Translation (II)

SGSN

SGSN

GGSNBSC

Internet

IP Packet

(IP Source,

IP Destination)



IP Source TLLI + NSAPI



IP Source TLLI + NSAPI

SNDCP (TLLI,

NSAPI, IP Packet)



TLLI + NSAPI TID + GGSN



TLLI + NSAPI TID + GGSN

GTP (

GGSN-Address,

TID, IP Packet)

IP Packet



GPRS Air Interface

GPRS utilizes the GSM-based FDMA/TDMA-combination with 8 time slots per TDMA frame.

GPRS supports a more flexible channel assignment scheme:

Multi-slot operations

Separate assignment of uplink and downlink for assymmetric traffic

Available channels are dynamically assigned to both kinds of traffic (Capacity on demand).

Several users may share one physical GPRS channel.


GPRS Logical Channels


Group Channel Function Direction

Traffic Channels Packet Data Traffic

Channel

PDTCH Packet Data Traffic MS BSS

Signaling Channels Packet Broadcast

Control Channel

PBCCH Packet Broadcast

Control

MS BSS

Packet Common

Control Channel

(PCCCH)

PRACH Packet Random Access MS BSS

PAGCH Packet Access Grant MS BSS

PPCH Packet Paging MS BSS

PNCH Packet Notification MS BSS

Packet Dedicated

Control Channels

PACCH Packet Associated Control MS BSS

PTCCH Packet Timing Advance

Control

MS BSS




Interworking with IP Networks

SGSN GGSN

DNS DNS

GPRS internal

IP NetworkFire-

wall

Intra-PLMN

GPRS Backbone

InternetRou-

ter

Gn Gn

Gi

WAP - Wireless Application

Protocol Goals

Internet contents and enhanced services shall be made available for mobile end devices like cell phones or PDAs

Independent standards for wireless networks Open standards: everybody may submit proposals for

standardization

Applications should be scalable and future-proof

Platforms

Many platforms must be supported: E.g. GSM (900, 1800, 1900), CDMA IS-95, TDMA IS-136, IMT-2000, UMTS,

W-CDMA

Forum

WAP Forum, founded by (among others) Ericsson, Motorola, Nokia, Unwired Planet

see http://www.wapforum.org




WAP Standardization

Browser

Micro-Browser, comparable to familar Internet browser

Scripting Language

Comparable to Java-Script, adapted to mobile enviroment

WTA/WTAI

Wireless Telephony Application (Interface): Access to telephone functionality

Contents Formats

E.g. business cards (vCard), calendar entries (vCalender)

Protocol Stack

Transport, Security and Session Layer

Working Groups

WAP Architecture Working Group, WAP Wireless Protocol Working Group,

WAP Wireless Security Working Group,

WAP Wireless Application Working Group



WAP 1.x Layers and Protocols

WAE includes e.g. WML (Wireless Markup Language), WML Script, WTAI

Bearer Services (GSM, Cellular Digital Packet Data, ...)

Security Layer (WTLS)

Session Layer (WSP)

Application Layer (WAE)

Transport Layer (WDP)TCP/IP,

UDP/IP,

Phys. Media

SSL/TLS

HTML, Java

HTTP

Internet WAP

Transaction Layer (WTP)

Additional services

and protocols

WCMP

A-SAP

S-SAP

TR-SAP

SEC-SAP

T-SAP




WAP Network Elements

Mobile NetworkFixed Network

WAP

Proxy

WTA

Server

Filter/

WAP

ProxyWeb

Server

Filter

Telephone

Network

Internet

Binary WML: Binary data format for clients

Binary WML

Binary WML

Binary WML

HTML

HTML

HTML WML

WMLHTML


Original ServerOriginal Server

Wireless Application Environment:

Logical Model

web

server

other

servers

GatewayGateway ClientClient

other

WAE

user agents

WML

user agent

WTA

user agent

Coder

&

Decoder

coded

request

request

coded

reply

reply

push

contents

coded

push

contents




Wireless Telephony Application:

Logical Architecture

Additional

Server

ClientClient

Repository

WTA-

User-Agent

WTA-GatewayWTA-Gateway

Coder&

Decoder

OtherTelephone

NetworksWTA-ServerWTA-Server

WTA & WML

Server

WML-

Scripts

WML-

StackWTA-

Services

Mobile

Network

FirewallExternal

Server

Secure Provider

Network

Device Spec.

Functions


Example Voice Box

Service Indication

WTA-User-Agent WTA-Server Mobile Network Voice Box

Create Content

Presentation;User Selection

ConnectionSetup

Accept Call

Voice connection

Indicate new voice message

Request to deliver voice message

Connection establishment

Call acceptance Call acceptance

WTA-Gateway

Push URL

Indication;User Selection

WSP Get HTTP Get

Reply with ContentWMLBinary WML

WSP Get HTTP GetReply with Card

for CallWMLBinary WML

Waiting for Call

Connection establishment




Possible Protocol Stacks for WAP 1.x

WAE

WSP

WTP

UDP

IP

(GPRS, ...)

WDP

non IP(SMS, ...)

WTLS

WAE user agentWAP Standard

Not part of WAP

WTP

UDP

IP

(GPRS, ...)

WDP

non IP(SMS, ...)

WTLS

UDP

IP

(GPRS, ...)

WDP

non IP(SMS, ...)

WTLS

Transaction-based

Applications

Datagram-based

Applications

typical WAP

Application based on

complete protocol

stack

Simple data transfer

with or without

security mechanisms

WAP 2.0 (July 2001)

New

XHTML

TCP with Wireless Profile

HTTP

Innovative Applications

Color graphics

Animation

Download of big files

Location-based services

Synchronization with PIMs

Pop-up/context-sensitive menus

Goal

Integration of WWW, Internet, WAP, i-mode





WAP 2.0 ArchitectureService

Localization

Security

Services

Applic

ation

Fra

mew

ork

Pro

tocol F

ram

ew

ork

External

Services EFI

Provisioning

Navigation

Discovery

Service

Lookup

Crypto-

Libraries

Authenti-

cation

Identification

PKI

Secure

Transport

Secure

Bearers

Se

ssio

nT

ran

sfe

rT

ran

sp

ort

Be

are

r

Multimedia Messaging

(Email)

WAE/WTA User Agent

(WML, XHTML)

Content

Formats

Push

IPv4

IPv6

CSD

SMS

USSD

FLEX

GUTS

MPAK

...

...

Datagrams

(WDP, UDP)

Connections

(TCP with

wireless profile)

Hypermedia Transfer

(WTP+WSP, HTTP)

Strea-

ming

MMS

Messa-

ges

Push

OTA

Capability Negotiation

Synchronization Cookies


WAP 2.0 Protocol Stacks

Trger

WDP

WTLS

WTP

WSP

WAE

WAP Device

Trger

WDP

WTLS

WTP

WSP

IP

TCP

TLS

HTTP

IP

TCP

TLS

HTTP

WAE

Web ServerWAP Gateway

WAP 1.x Server/Gateway/Client

IP

TCP

TLS

HTTP

WAE

WAP Device

IP

TCP

IP

TCP

IP

TCP

TLS

HTTP

WAE

Web ServerWAP Proxy

WAP Proxy with TLS-Tunneling

IP

TCP

HTTP

WAE

WAP Device

IP

TCP

IP

TCP

IP

TCP

WAE

Web ServerWAP Proxy

WAP HTTP Proxy with adapted TCP

HTTP HTTP HTTP

IP

TCP

HTTP

WAE

WAP Device

IP IP IP

TCP

WAE

Web-Server

IP Router

WAP direct access

HTTP



References

SCHILLER, J.: Mobile Communications,

2nd edition, Addison-Wesley, 2003,

ISBN 0-321-12381-6.

(Thanks for the Powerpoint Slides!!)


Documents

GSM & GPRS