Mobile Communication and Mobile Computing

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Mobile Communication and Mobile Computing 1 Mobile Communication and Mobile Computing Prof. Dr. Alexander Schill TU Dresden, Computer Networks Dept. http://www.rn.inf.tu-dresden. de

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Mobile Communication and Mobile Computing. Prof. Dr. Alexander Schill TU Dresden, Computer Networks Dept. http://www.rn.inf.tu-dresden.de. Contents. 1. Motivation 2. Mobile Communication History Principles Media Access Methods Mobile Radio Networks: Overview GSM HSCSD, GPRS UMTS. - PowerPoint PPT Presentation

Transcript of Mobile Communication and Mobile Computing

Page 1: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing1

Mobile Communication andMobile Computing

Prof. Dr. Alexander Schill

TU Dresden, Computer Networks Dept.

http://www.rn.inf.tu-dresden.de

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Contents

1. Motivation

2. Mobile Communication– History– Principles– Media Access Methods– Mobile Radio Networks: Overview– GSM– HSCSD, GPRS– UMTS

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Contents

2. Mobile Communication (Continuation)– Broadband-Radio Systems– Wireless Local-area Networks (IEEE 802.11,

Bluetooth etc.)– Satellite-based Systems

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Contents3. Mobile Computing

– Layer 3• MobileIP v4 & v6• DHCP

– Layer 4– Higher Layers and Services

• WAP, XML• Mobile RPC• CODA, Databases• Mobile Agents• Middleware for spontaneous networking• Services and system support for Mobile Computing

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Roth, J.: Mobile Computing, dpunkt-Verlag, 2002Very good overview to mobile communication and mobile computing

Schiller, J., Mobilkommunikation, Techniken für das allgegenwärtige Internet, Addison-Wesley, 2000

Mobile Communication principles and Mobile Computing

Bernhard, Walke: Mobilfunknetze und ihre Protokolle, 2 Bände. Teubner, 2000Principles, GSM, UMTS and other cellular Mobile Radio Networks [Vol.1] Circuit Switched Radio, Cordless Phone Systems, W-ATM, HIPERLAN, Satellite Radio, UPT [Vol.2]

Schumny, Harald: Signalübertragung, Friedrich Vieweg & Sohn, Braunschweig/Wiesbaden 1987;

Wave propagation and wireless transmission

A.S. Tanenbaum: Computernetzwerke, 4. Aufl., Prentice Hall, 1998Protocols, ISO/OSI, standards, fixed networksPrinciples

Literature

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1. Motivation and Examples

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Speech- and Data Communication location independent and mobile

New application areas, flexibility, improved workflows

Requirements:- Mobile end-devices- Radio transmission- Localization and signalization/management- Standards

- Application Concepts for mobile end-devices in distributed systems

- Control of heterogeneous, dynamic infrastructures

Mobile Computing

Motivation

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Building site

ArchitectBuilding ofenterprise A(main office)

Building ofenterprise B

Construction supervisor

X.25ISDNATM

ATM ISDN

GSM GSM

Selected drafts,Videoconferences

Material data,status data,dates

Large archives,Videoconferences

Drafts,urgent modification

Building ofenterprise A(branch office)

Application example: Civil Engineering, Field Service

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WAP-Example: Order processing

Order book

• Status of bond transactions.

• Executed and deleted orders are indicated in the order book for some days more.

• Partial execution of some order is presented as one open and one executed partial order in the order book.

• Details to an order could be indicated via dial-up of correspondent Links.

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Product Data

Main officeCaching

ClientLAN-Access

Maintenance technician

- very different performance and charges: radio networks versus fixed networks

Software-technical, automatic adaptation to concrete system environmentExample: Access to picture data/compressed picture

data/graphics/text

Mobile Access

Local Resources,Error Protocols

Perspective: Mobile Multimedia Systems

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Ethernet

Ethernet

Ethernet

E-Fax-OrderE-Fax-Order

ManagementDB-Access

ManagementDB-Access

FirmBranch office

Client X

GSM

xDSL

Application

Resource

Mobile Station

Communication path

DBDistributed Database

Distributed Database

Cache

Application Structure

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Internet

Content Provider

Main Office

Infrastructure

GSM

GSM

Radio/Infrared

ATM

GSM, RDS/TMC, DAB...

Beam Radio, ISDN

GSM

Traffic Telematics Systems

Content Provider

DAB: Digital Audio Broadcast

RDS/TMC: Radio Data System/ Traffic Message Channel

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GSM (Global System for Mobile Communications): worldwide standard for digital, cellular Mobile Radio Networks

UMTS (Universal Mobile Telecommunications System): European Standard for future digital Mobile Radio Networks

AMPS (Advanced Mobile Phone System): analog Mobile Radio Networks in USA

DECT (Digital Enhanced Cordless Telecommunications): European standard for cordless phones

TETRA (Terrestrial Trunked Radio): European standard for circuit switched radio networks

ERMES (European Radio Message System): European standard for radio paging systems (Pager)

802.11: International standard for Wireless Local Networks

Bluetooth: wireless networking in close/local area

Inmarsat: geostationary satellite systems

Teledesic: planned satellite system on a non-geostationary orbit

Mobile Communication Networks: Examples

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Mobile Communication: Development

2005200019951990

D (GSM900)C

Cordless Telephony

Mobile Phone Networks

Packet Networks

Circuit Switched Networks

Satellite Networks

Local Networks

Modacom

Mobitex

Tetra

Inmarsat

IR-LAN

MBS

IMT2000/UMTS

IEEE 802.11/Hiperlan

Radio-LAN

Iridium/Globalstar

E (GSM1800)

EDGEHSCSD

GPRS

CT2 DECT

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Used Acronyms

CT2: Cordless Telephone 2. Generation

HSCSD: High Speed Circuit Switched Data

GPRS: General Packet Radio Service

EDGE: Enhanced Data Rates for GSM Evolution

IMT2000: International Mobile Telecommunications by the year 2000

MBS: Mobile Broadband System

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2. Mobile Communication

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Principles

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Mobile Communication

Tied to electro-magnetic radio transmission

radio transmission

terrestrial orbital (satellite)

beam radiobroadcast radio

equatorial orbit

non-equatorialorbit

cellular non-cellular

Principles:– Propagation and reception of electro-magnetic waves– Modulation methods and their properties– Multiplex methods– Satellite orbits/Sight- and overlap areas

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Cellular Networks: Principles

Supply- (radius R) and interference areas (5 R)

7-Cell-Cluster (repeat sample of the same radio-channels)

Interference Zone

R

Channels801-1600

Channels 1-800

Channels 1-800

5R

15

6

6

3

7

4

4

2

7

5

34

1

1

5

2

7

73

2

6

4

56 3

5

15

6

6

3

7

4

4

2

1

7

2

5

32

14 24

12

R

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Cell structure: Example

Reference cell

Cell in the interference area of the reference cell

Further cells, whose channel distribution should be known to the reference cell

Cellular Networks: Principles

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Kinds of antennas: directional & sectored

• Energy is radiated in definite directions, for instance x-Direction

• So called main propagation directions, for instance Satellite Antennas

• Often also used in Mobile Radio Systems, such as GSM, for creation of sectored cells

• Seamless radio supply via partial/overlay of sectors

x

y

x

z

Directional Antenna Sectored Antenna

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Media Access Methods

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Principles

• Multiplex– Multiple-shift usage of the medium without interference– 4 multiplex methods:

• Space• Time• Frequency• Code

• Media Access Methods– controls user access to medium

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SDMA (Space Division Multiple Access)

• based on SDM (Space Division Multiplexing, Space Multiplex)• communication channel obtains definite Space for definite Time on

the definite Frequency with definite Code• Space Multiplex for instance in the Analog Phone Systems (for each

participant one line) and for Broadcasting Stations• Problem: secure distance (interferences) between transmitting

stations is required (using one frequency) and by pure Space Multiplex each communication channel would require an own transmitting station

• Space Multiplex is only reasonable in combination with other multiplex methods

• SDMA for instance by base station dedication to an end-device via Media Access Methods or respectively by segmentation of a Mobile Radio Network to several areas

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SDMA: Example

k1 k2

s

s – secure distance

k3 k4 k5 k6

SDMA finds selection

f1

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FDMA (Frequency Division Multiple Access)

• Based on FDM (Frequency Division Multiplexing, Frequency Multiplex)

• i.e. to transmission channels several frequencies are permanently assigned, for instance radio transmitting stations

k1 k2 k3 k4 k5 k6

f1

f2

f3

f4

f5

f6

s – secure distance

s

FDMA findsselection

t

f

k1

k2

k3

k4

k5

k6

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TDMA (Time Division Multiple Access)

• Based on TDM (Time Division Multiplexing, Time Multiplex)• i.e. to transmission channels is the transmission medium is slot

assigned for certain time, is often used in LANs • Synchronization (timing, static or dynamic) between transmitting and

receiving stations is required

k1 k2 k3 k4 k5 k6

f1

t

f

k1 k2 k3 k4 k5 k6 k1

TDMA findsselection

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Combination: FDMA and TDMA, for instance GSM

• GSM uses combination of FDMA and TDMA for better use of narrow resources

• the used band width for each carrier is 200 kHz

t

f in MHz

TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0

TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0

TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0

TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0

TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0

TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0

890,2

915200 kHz

935,2

960

25 MHz

45 MHz

25 MHz

uplink

downlink

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CDMA (Code Division Multiple Access)

• based on CDM (Code Division Multiplexing, Code multiplex)• i.e. to transmission channels the definite Code is assigned, this can

be on the same Frequency for the same Time transmitted• derivates from military area• via development of cost-efficient VLSI components• via spread spectrum techniques a good communication security and

tiny fault sensitivity• but: exact synchronization is required, code of transmitting station

must be known to receiving station, complex receivers for signal separation are required

• Noise should not be very high

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CDMA

k1 k2 k3 k4 k5 k6

f1

CDMAdecoded

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The Principle of CDMA can be good illustrated by the example of some party:

• communication partners stand closely to each other, each transmission station (Sender) is only so loud, that it does not interfere to neighbored groups

• transmission stations (Senders) use certain Codes (for instance, just other languages), they can be just separately received by other transmission stations

• receiving station (Listener) attunes to this language (Code), all other Senders are realizing this only as background noise

• if receiving station (Listener) cannot understand this language (Code), then it can just receive the data, but it cannot do anything with them

• if two communication partners would like to have some secure communication line, then they should simply use a secret language (Code)

• Potential Problems:– security distance is too tiny: interferences (i.e. Polish und

Czech)

CDMA illustrated by example

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Sender A• Sends Ad =1, Key Ak = 010011 (set: „0“= -1, „1“= +1)• Transmit signal As =Ad *Ak = (-1, +1, -1, -1, +1, +1)Sender B• sends Bd =0, Key Bk = 110101 (set: „0“= -1, „1“= +1)• Transmit signal Bs =Bd *Bk = (-1, -1, +1, -1, +1, -1)

Both signals superpose additively in air• Faults are ignored here (noises etc.)• C = As+ Bs =(-2,0,0,-2,+2,0)

Receiver will listen to Sender A• uses Key Ak bitwise (internal product)

– Ae = C * Ak =2 +0+0 +2 +2+0 = 6– Result is greater than 0, so sent bit was „1“

• analog B– Be = C * Bk =-2 +0 +0 -2 -2 +0 = -6, also „0“

CDMA-Example in the theory

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Spread Spectrum Techniques

• Signal is spread by the Sender before the transmission (overblown) • dP/df value corresponds with so called Power Density, Energy is

constant (in the Figure: the filled areas)

Objective:• Increase of robustness against small band-width faults• listening security: power density of spread-spectrum signals can be

lower than that of background noise

df

dP

f

df

dP

f

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Spread Spectrum Techniques

• small band-width faults are spread by de-spreading in receiving station

• band-pass deletes redundant frequency parts

df

dP

f

df

dP

f

df

dP

f

t

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Mobile Radio Networks: Overview

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General technological development in mobile telephony

before 1970 1970 1980 2000 2005

Analog Networks...150Mhz

1990

Anal. cellular Networks...450 Mhz

Anal. cellular Networks...900 Mhz

Digital cellular Networks...900 Mhz

Digital cellular Networks...1800 Mhz

GSM Phase II+

UMTS

Satellite Systems (LEO)

Prognoses

Development of Mobile Radio

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Correspondent data rates

1995 2000 2005 2010

10kbit/s GSM

HSCSD/GPRS

EDGE

100kbit/s

1Mbit/s

10Mbit/s

UMTS (pico cell)

UMTS(macro cell)

DAB

Satelliten

DECT

(GEO)Satellites (GEO)

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365190830; 32%

369094290; 32%

137691590; 12%

165417440; 14%

37534680; 3%

20059880; 2%

53069620; 5%

1

2

3

4

5

6

7

Participant quantities in Mobile Radio – world-wide

November 2002: 1148 Mio. participants world-wide (1119 Mio. digital & 29 Mio analog)

1... Europe: Western 4... Americas (thereof 15.4 Mio. analog)

2... Asia Pacific 5... USA/Canada (thereof 5.4 Mio. analog)

3... Middle East 6... Africa

7… Europe: Eastern

(Source: http://www.emc-database.com)

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Frequency Assignment

TETRA

380-400

410-430

NMT

453-457

463-467

CT2

864-868

CT1+

885-887 890-915

GSM900 CT1+

930-932

GSM900

935-960

TFTS (Pager, aircraft phones) GSM1800

1670-1675 1710-1785 1800-1805

TFTS

1805-1880

GSM1800 DECT

1880-1900 (1885-2025

2110-2200)

TETRA

450-470

(nationally different)

UMTS

IEEE 802.11b

2400-2483

HIPERLAN1

5176-5270

MHz

Bluetooth

2402-2480

HIPERLAN2

(ca.5200,5600)

WLAN

2412-2472HomeRF...(approx.2400)

Circuit Switched Radio Mobile Phones Cordless Phones Wireless LANs

Notes: - 2,4 GHz license free, nationally different- () written : Prognoses!- today speech over license free frequencies up to 61Ghz -> interesting for high data rates

(ca.17000)

HIPER-Link

1GHz500Mhz

TFTS - Terrestrial Flight Telephone System

IEEE 802.11a: 5,15-5,25; 5,25-5,35; 5,725-5,825

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Broadcast/multicast networks

• several carrier frequencies but participant obtains carrier for short time only

• often in use by taxi- und logistics enterprises etc., each own separated frequency reaches

• can use the same frequency packs with FDM- and TDM- techniques, i.e. more efficient handling with narrow resource frequency spectrum

• improves transition to fixed network, speech- and data services

• not for public access • very reliable, cost-efficient

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TETRA (Terrestrial Trunked Radio)

• former name: Trans-European Trunked Radio• frequencies: 380-390, 410-420 MHz Uplink; 390-400, 420-430 MHz

Downlink• bandwidth of each channel: 25 kHz• 1991 started by ETSI• replace of national networks like MODACOM, MOBITEX or

COGNITO• Services:

– Voice + Data (V+D)- Service: Speech and Data, channel-oriented, uni-, multi- and broadcast possible

– Packet Data Optimized (PDO)- Service: packet-oriented, improves connection-oriented or connectionless service, as well as point-to-point and point-to-multipoint communication

• carrier services with data rate up to 28,8 kbit/s unprotected; 9,6 kbit/s - protected

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TETRA, advantages compared with GSM, UMTS

• confirmed and/or non-confirmed Group Call (however it’s already possible with GSM today: up to 16 participants)

• Group call• listening is possible (so called “open-channel mode”)• very reliable• fast dialing: approx. 300 ms (so called “push to talk”), GSM: several

seconds• certain independence of infrastructure (so called “direct mode”

between end-devices)• cost-efficient, especially for limited user quantity, because of the

„large“ cells x • 10 km• also especially suitable for emergency teams (fire department,

ambulance etc.)

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Cordless Telephony - DECT (Digital Enhanced Cordless Telecommunications)

• frequency reach: 1880 - 1990 MHz• other than GSM limited to short reaches (1km)• in buildings particularly under 50m• is not designed for use at high rates• mobile phones with GSM and DECT are available in the market• 120 full duplex channels• TDD (Time Division Duplex) for directional separation with 10ms

frame length• frequency reach is divided into 10 carrier frequencies using FDMA• each station 10mW averaged, max. 250mW of transmitting power,

GSM – radio phones transmit at 1 to 2W, fixed car phones up to 8W

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PA

PA

PT

PT

FT

FT

D4 D3 D2

Local Networks

Local Networks

HDB

VDB

Global Networks

D1

FT.. Fixed Radio Termination

PT.. Portable Radio Termination

PA... Portable TerminationsHDB.. Home Data BaseVDB.. Visitor Data Base

DECT – system architecture

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64 bit8 bit160 bit48 bit32 bit

Synchronization SignalizationUsed Data

(Speech)CRC Used Data

(Speech) CRC Secure marker

160 bit 8 bit

0,417 ms

DECT-timeslot structure

Transmission reach of fixed part (downlink) Transmission reach of mobile part (uplink)

carrier frequency 1:1 2 3 4 5 6 .... 11 12 1' 2' 3' 4' 5' 6' .... 11' 12'

1 2 3 4 5 6 .... 11 12 1' 2' 3' 4' 5' 6' .... 11' 12'

1 2 3 4 5 6 .... 11 12 1' 2' 3' 4' 5' 6' .... 11' 12'

.

.

.

.

.

.

.

.

.

1728kHz

Transmission principle of DECT-system

Channel 1 Channel 2 Channel 12 Channel 1’ Channel 2' Channel 12'. . . . . .

fixed part to mobile part mobile part to fixed part

Time duplex with 10 ms frame length

Structure of DECT-time multiplex frame

DECT - Multiplex

carrier frequency 2:

carrier frequency 10:

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Eurosignal

– to each participant 4 different audio signals using 4 diverse call numbers are assigned. Meaning must be agreed. Receiving stations are at a size of a cigarette packet

– 85 senders in the 87 MHz-reach (ultra short waves)

– called person location must be approximately known: 3 area codes: North 0509, Middle 0279, South 0709

Cityruf (city call)

– additionally to 4 audio- or respectively optical signals transmission of short numerical (15 digitals) or alpha-numerical messages (80 characters) exists optionally, receiving station is smaller than with Eurosignal

PEP (Pan European Paging)

– preparation for coupling of national services for ERMES

– D: Cityruf, F: Alphapage, GB: Europage, I: SIP

ERMES (European Radio Message System)

– ETSI-Standard for pan-European radio service, similar to PEP but in 169 MHz-reach with 60 Mio. addresses

Pager systems: overview

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GSM: Global System for Mobile Communications

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GSM: Properties• cellular radio network (2nd Generation)• digital transmission, data communication up to 9600 Bit/s• Roaming (mobility between different net operators, international)• good transmission quality (error detection and -correction)• scalable (large number of participants possible)• Security mechanisms (authentication, authorization, encryption)• good resource use (frequency and time division multiplexing)• integration within ISDN and fixed network• standard (ETSI, European Telecommunications Standards Institute)

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Providers in Germany (1)

• D1 T-Mobile – subscribers: 24,6 Mio (Stand 2003)

• Vodafone D2 – old name: Mannesmann Mobilfunk D2

– subscribers: 22,7 Mio (Stand 2003)

• E-plus

• O2 – old name: VIAG Interkom

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Providers in Germany (2)

Providers Subscribers, millions

2001 2002 2003 World-wide by 2003

D1 T-Mobile 22,6 23,1 24,6 82

Vodafone D2 21,9 - 22,7 112,5

E-Plus - 7,5 - -

O2 VIAG Interkom

- 3,66 - -

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AuC Authentication CentreBSS Base Station SubsystemBSC Base Station ControllerBTS Base Transceiver StationEIR Equipment Identity RegisterHLR Home Location Register

MS Mobile Station(G)MSC (Gateway) Mobile Switching CentreOMC Operation and Maintenance CentrePSTN Public Switched Telephone NetworkVLR Visitor Location RegisterISDN Integrated Services Digital Network

Fixed network Switching Subsystems

VLR

Radio Subsystems

HLR AuC EIR

(G)MSC

OMC

BTS

BTSBSC

BSS

MS

MS

Network ManagementCall Management

Data networks

PSTN/ISDN

MS

GSM: structure

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GSM: StructureOperation and Maintenance Centre (OMC)• logical, central structure with HLR, AuC und EIR

Authentication Centre (AuC)• authentication, storage of symmetrical keys, generation of

encryption keys

Equipment Identity Register (EIR)• storage of device attributes of allowed, faulty and jammed

devices (white, grey, black list)

Mobile Switching Centre (MSC)• arrangement centre, partial as gateways to other nets, assigned

to one VLR each

Base Station Subsystem (BSS): technical radio centre• Base Station Controller (BSC): control centre• Base Transceiver Station (BTS): radio tower / antenna

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1 TDMA-Frame, 144 Bit in 4,615 ms

8 TDMA-channels, together 271 kBit/s inclusive error protection information

124 radio frequency channels (carrier), each 200 kHz

2 frequency wavebands, for each 25 MHz, divided into radio cells

890

935

915 MHz

960 MHz

downlink

uplink

Radio technical structure

• One or several carrier frequencies per BSC • Physical channels defined by number and position of time slots

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GSM: protocols, incoming callVLR

BS

S

BSS MSC GMSC

HLRBSS

BSS

(4)

(2)(4)

(5)

(3)

(10)(6)

(11)(7)(8)

(8)(9)

(12)

(8)

(1)

(12)

(9)(8)

PSTN/ISDN

(1) Call from fixed network was switched via GMSC

(2) GMSC finds out HLR from phone number and transmits need of conversation

(3) HLR checks whether participant for a corresponding service is authorized and asks for MSRN at the responsible VLR

(4) MSRN will be returned to GMSC, can now contact responsible MSC

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GSM: protocols, incoming callVLR

BS

S

BSS MSC GMSC

HLRBSS

BSS

(4)

(2)(4)

(5)

(3)

(10)(6)

(11)(7)(8)

(8)(9)

(12)

(8)

(1)

(12)

(9)(8)

PSTN/ISDN

(5) GMSC transmits call to current MSC

(6) ask for the state of the mobile station

(7) Information whether end terminal is active

(8) Call to all cells of the Location Area (LA)

(9) Answer from end terminal

(10 - 12) security check and connection construction

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GSM: protocols, outgoing call

VLR

BS

S

BSS MSC GMSC

HLRBSS

(5)

(3)(4)

(2)(1)

(1) Demand on connection

(2) Transfer by BSS

(3-4) Control for authorization

(5) Switching of the call demand to fixed net

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GSM: channel strucureTraffic Channel• speech- / data channel (13 kbit/s brutto; differential encoding)• units of 26 TDMA - Frames• Half-rate traffic channel: for more efficient speech encoding with

7 kbit/sControl Channel• Signal information • Monitoring of the BSCs for reconnaissance of HandoverBroadcast Control Channel• BSC to MS (identity, frequency order etc.)Random Access Channel• Steering of channel entry with Aloha-procedurePaging Channel• signalize incoming calls

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DatabasesHome Location Register (HLR), stores data of participants, which

are reported in an HLR-area – Semi-permanent data:

• Call number (Mobile Subscriber International ISDN Number) - MSISDN, e.g. +49/171/333 4444 (country, net, call number)

• identity (International Mobile Subscriber Identity) - IMSI: MCC = Mobile Country Code (262 for .de) + MNC = Mobile Network Code (01-D1, 02-Vodafone-D2, 03-eplus, 07-O2) + MSIN = Mobile Subscriber Identification Number

• Personal data (name, address, mode of payment)• Service profile ( call transfer, Roaming-limits etc.)

– Temporary data:• MSRN (Mobile Subscriber Roaming Number) (country, net, MSC)• VLR-address, MSC-address

• Authentication Sets of AuC (RAND (128 Bit), SRES (128 Bit), KC (64Bit))

• charge data

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DatabasesVisitor Location Register (VLR)• local database of each MSC with following data:

– IMSI, MSISDN– service profile– accounting information – TMSI (Temporary Mobile Subscriber Identity) - pseudonym for data

security– MSRN– LAI (Location Area Identity)– MSC-address, HLR-address

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MSC-area = VLR-area

radio-cell

with BTS

Location Area (LA)

LA = smallest addressable unit

Handover

GSM: mobile telephone areas

Page 61: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing61

MSC-area

HLR

VLR

Location

area advantage of the architecture: Location Update at limited mobility, as a rule only at VLR, rarely at (perhaps far remote) HLR

Connection HLR, VLR

Page 62: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing62

LA 5

LA 3LA 2

LA 3

VLR 10 VLR 9IMSI LA 2

HLR 2632311 VLR 9 IMSI

participant call numberin HLR

country code number

net-entry code

Provider

+49 0177-26 32311

0x62F220 01E5z.B.

Localization at GSM

Page 63: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing63

Data transmission

• each GSM-channel configurable as a data channel; similar structure like ISDN-B and -D-channels

• data rates up to 9600 bit/s now

• delay approximately 200 ms

• speech channels have as a rule higher priority as data channels

• kinds of channels:– transparent (without error correction; however FEC; fixed data rate; error rate 10-3

up to 10-4) – non-transparent (repeat of faulty data frames; very low error rate, but also less

throughput)

• Short-Message-Service (SMS)– connectionless transmission (up to 160 Byte) on signal channel

• Cell Broadcast (CB)– connectionless transmission (up to 80 Byte) on signal channel to all participants,

e.g. one cell

Page 64: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing64

MSCBSC

UDI

BTS

IWF

TA

ISDN

Modem

PSTN

Internet

Modem

IWF - Inter Working Function

UDI - Unspecified Digital

TA - Terminal Adapter

Data transmission - structure

Page 65: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing65

Chip-card (Smart Cart) to personalize a mobile subscriber (MS):

• IMSI (International Mobile Subscriber Identity)• participant special symmetric key Ki, stored also at AuC • algorithm “A3” for Challenge-Response-Authentication• algorithm “A8” for key generation of Kc for content data• PIN (Personal Identification Number) for entry control

Temporary data:• TMSI (Temporary Mobile Subscriber Identity)• LAI (Location Area Identification)• Encryption key Kc

Security aspects: Subscriber Identity Module (SIM)

Page 66: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing66

Security in GSM-networks

SIM• Entry control and cryptographic algorithmsSingle-sided authentication (participant against network) • Challenge-Response-method (cryptographic algorithm:

A3)Pseudonyms of participants at the Radio interface• Temporary Mobile Subscriber Identity (TMSI)Connection encoding on the Radio interface • Key generation: A8• Encryption: A5

Page 67: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing67

Security aspects: Authentication

MSC, VLR, AuCMS

Authentication RequestRAND (128 Bit)

Random numbergenerator

iK

A3

SRES

SRES (32 Bit)

A3

iK

Authentication Response=

• Location Registration• Location Update with VLR-change• Call setup (in both directions) • SMS (Short Message Service)

max. 128 Bit

Page 68: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing68

Security aspects: Session Key

NetzMS

Authentication RequestRAND (128 Bit)

Random numbergenerator

iK

A8

A8

iK

cK 64 Bit

cK

• Key generation: Algorithm A8– Stored on SIM and in AuC

– with Ki parametric one way function

– no (Europe, world wide) standard– can be determined by net operator – Interfaces are standardized– combination A3/A8 known as COMP128

Page 69: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing69

Security aspects: encryption at the Radio interface

NetMS

Ciphering Mode Command

A5A5

• Data encryption through algorithm A5:– stored in the Mobile Station – standardized in Europe and world wide – weaker algorithm A5* or A5/2 for specific countries

cKcKTDMA-frame-number

TDMA-frame-number

Key block

+Plain text block

+Plain text block

Ciphering Mode Complete

Encrypted Text

114 Bit

Page 70: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing70

GSM-Security: assessment• cryptographic methods secret, so they are not „well

examined“• symmetric procedure

– consequence: storage of user special secret keys with net operators required

• low key length Ki with max. 128 Bit (could be hacked by using Brute Force Attack in 8-12 hours)

• no mutual authentication intended– consequence: Attacker can pretend a GSM-Net

• no end-to-end encryption• no end-to-end authentication• Key generation and -administration not controlled by the

participants

Page 71: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing71

GSM Phase II+HSCSD, GPRS

Page 72: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing72

HSCSD: High Speed Circuit Switched Data

Page 73: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing73

• higher data rate because of channel bundling• parallel usage of several time slots (TCH) of one

frequency on Um

• more efficient channel encoding (14,4 kbit/s per TCH)• Data rates from 9,6 up to 53,8 kbit/s• asymmetric transmission (1TCH Uplink /

3TCH Downlink)

Properties

Page 74: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing74

HSCSD data rates

transparent non transparent

up- / downlink 100% coverage 95% coverage 100% coverage 95% coverage

1 + 1 9,6 14,4 9,6 13,22 + 2 19,2 28,8 19,2 26,41 + 3 --- ---- 28,8 39,61 + 4 --- ---- 38,4 53,8

Page 75: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing75

MSCBSC

UDI

BTS

IWF

TA

ISDN

Modem

PSTN

Internet

Modem

IWF - Inter Working Function

UDI - Unspecified Digital

TA - Terminal Adapter

n time slots (TCH) of each

TDMA frame(theoretically max. 8)

HSCSD: structure

Page 76: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing76

Um Abis A

MSCBSCBTS

n time slots (TCH) of each TDMA frame

(theoretically max. 8)

multiplex of thetime slots

on each 64 kBit/schannel

certain changes are necessary at the componentseveral changes at the software/firmwareminimal changes at the software/firmware

HSCSD: changes

Page 77: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing77

• parallel usage of several time slots limited to one frequency

• Cost factor limits number of used TCH‘s to (2+2) or (1+3, uplink, downlink)

Required time for setting to receiving standby

7654321076543210

4321076543210765

Required time for setting to transmission standby

Required time for signal strength measure and setting to receiving standby

MS RECEIVE

MS TRANSMIT

MS MONITOR

HSCSD radio interface

Page 78: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing78

Assessment of HSCSD

+ existing net structure and accounting model maintained + in comparison to GPRS only around1/5 of investment

necessary+ HSCSD is still circuit switched

+ has defined QoS- settings (data rate, delay)– one logical channel will be switched on all interfaces for the time

of the connection– Non-efficient for burst-like traffic (Internet) or Flat Rate billing

(Logistics)– no international acceptance (Roaming!)

• uses also more resources on the radio interface– problems with handover into a new cell

Page 79: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing79

GPRS: General Packet Radio Service

Page 80: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing80

Properties

• Packet switching service (end- to- end)• Data rates up to 171,2 kbit/s (theoretical) • Effective and flexible administration of the radio interface• adaptive channel encoding• Internetworking with IP- and X.25 nets standardized• dynamic sharing of resources with „classical“ GSM

speech services • Advantage: Billing and Accounting according to data

volume• Disadvantage: cost intensive additional net hardware

necessary

Page 81: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing81

Properties

– point-to-point-Packet transfer service • PTP-CONS (PTP Connection oriented Network Service)

– connection oriented, similar to X.25• PTP- CLNS (PTP Connectionless Network Service)

– connectionless, similar to IP

– point- to- multipoint- group communication

Page 82: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing82

MSCBSC

BTS

Internet

GPRS: Structure

HLR

GSM

GPRS BackboneFrame Relay / ATM

GGSNGGSN

SGSNBorder

Gateway

GPRS Netsother operators

other packetswitching networks

SGSN - Serving GPRS Support Node

GGSN - Gateway GPRS Support Node

signalization data

user data

Page 83: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing83

GMSC

Circuit switched traffic

HLR/AuCGPRS register

MAP

MAPA

GGSN

GPRS: Changes

Abis

Gb

Gn

Gi

other packetswitching networks

publicremote fixed nets

Packet arrangedtraffic

Gs

Um

n time slots (TCH) per TDMA frame

(theoretically max. 8)per packet!

modified network components

new components or extensively modified components

Existing componentsPCU - Packet Control Unit

SGSN

MSC

BSCBTS

PCU

Page 84: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing84

SGSN:- mobility management- session management- QoS- security

External Data Domain

Intranet

SGSN

HLR

Internet

MAPSignalization(SGSN)

Tasks: SGSN, GGSN

BSSPCU

BSSPCU

BSSPCU

Client

GGSNClient

Server

MAPSignalization

(GGSN)

SGSN, GGSN:- Routing- Signalization - Resource management

SGSN

Page 85: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing85

Tasks of the SGSN• Packet delivery • mobility management

– apply/ sign off of terminals– localization

• LLC (Logical Link Control) management• authentication• billing

Page 86: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing86

Tasks of the GGSN• mediator between GPRS backbone and

external data networks (Internet, X-25 etc.) • converts GPRS packets, data Protocol

(PDP) into the corresponding structure • also converts PDP addresses of incoming

packets into GSM address of the receiver• saves current data for the SGSN address

of the participant as well as their profile and data for authentication and invoice

Page 87: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing87

Radio Link Control (RLC)• Segmentation of the LLC-Frames in RLC blocks• Block size dependent on short-term channel

conditions • Backward error correction and data flow control by

Automatic Repeat Request (ARQ) protocol– repeating not repairable RLC blocks selectively

Medium Access Control ( MAC)• Channel reservation contains:

- one/several time slots (Packet Data Channels PDCH) of one frequency– one uplink status flag (USF) per Packet Data Channel

(PDCH), channel partition of up to 8 ms

GPRS: air interface

Page 88: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing88

Medium Access Control ( MAC)• Reservation in the uplink (MS to BSS):

• MS sends reservation request on a Random Access Channel (Slotted ALOHA)– BTS allocates a (split) channel and sends packet assignment– MS sends data depending on the current priority (USF flag)

• Reservation in the Downlink (BSS to MS):

– BTS displays transmitting request and informs about the reserved channel

– MS supervises the reserved channel and receives

GPRS: air interface

Page 89: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing89

Physical Link Control• adaptive forward error correction (FEC) dependent on short-

term channel conditions • temporal scrambling (Interleaving) of the bursts and Mapping on

reserved PDCH (Packet Data Channel) • procedure to recognize overbooking situations on the physical

channel

GPRS: air interface

GPRS Channel Encoding

Scheme CodeRate

Payload BCS Pre-codedUSF

Tail bits Codedbits

Puncturedbits

Datarate

(kbit/s)

CS-1 1/2 181 40 3 4 456 0 9.05

CS-2 ~ 2/3 268 16 6 4 588 132 13.4

CS-3 ~ 3/4 312 16 6 4 676 220 15.6

CS-4 1 428 16 12 0 456 0 21.4

Page 90: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing90

Quality of Service• QoS profile agrees service parameters inside the whole network• Agreed for the duration of one PDP (Packet Data Protocol)

context (session, end terminal is obtainable for the duration of the context, e.g. obtainable over Internet ) :– temporary address (IP) for mobile station– tunneling information, among others GGSN, which is used for

access to corresponding packet arranged network – type of the connection– QoS profile

• QoS profile commits:– precedence class, priority against other services (high, normal, low)– packet delay class, times are valid for traffic inside the GPRS-

network– reliability class– peak throughput class– mean throughput class

Page 91: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing91

Quality of Service

Size 128 octets 1024 octets

Class Mean Delay 95% Delay Mean Delay 95% Delay

1 (predictive) < 0,5 s < 1,5 s < 2 s < 7 s

2 (predictive) < 5 s < 25 s < 15 s < 75 s

3 (predictive) < 50 s < 250 s < 75 s < 375 s

4 (best effort) Best effort

Probability for

Class Lost packetDuplicated

packet

Out ofSequence

packet

Corruptedpacket

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

Packet delay classes

Security classes

Page 92: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing92

Quality of Service

GPRS- using data ratesCoding # of timeslotsScheme 1 2 3 4 5 6 7 8

CS-1 9,05 18,1 27,15 36,2 45,25 54,3 63,35 72,4CS-2 13,4 26,8 40,2 53,6 67 80,4 93,8 107,2CS-3 15,6 31,2 46,8 62,4 78 93,6 109,2 124,8CS-4 21,4 42,8 64,2 85,6 107 128,4 149,8 171,2

• CS 3 and CS 4 are only reasonable in the second phase of GPRS introduction

• They will be used adaptively at corresponding good quality of radio connection

• CS 4 does not comprise error correction, code rate = 1!

Page 93: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing93

Assessment of GPRS

+ An up to 4 times higher data rate in comparison to ordinary GSM- data services

+ better resource management through packet arranged service+ „always on” data service (email, etc.)+ GPRS is a more suitable carrier for services like WAP

- IP-derivate, no true guaranties (QoS)

- development of the network infrastructure is relatively expensive, particularly regarding introduction to UMTS (return of investment)

- GPRS doesn’t give such data rates like advertising has sometimes promised

Page 94: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing94

9.6 kbit/s9.6 kbit/s

Da

ta r

ate

26.4 kbit/s26.4 kbit/s

13.2 kbit/s13.2 kbit/s

HS

CS

DC

ha

nne

l pa

ckin

g, N

TH

SC

SD

Ch

ann

el p

ack

ing

, NT

39.6 kbit/s39.6 kbit/s

CS 1CS 1

GP

RS

Pa

cke

t arr

ang

ed

GP

RS

Pa

cke

t arr

ang

ed

9 kbit/s9 kbit/s

18.1 kbit/s18.1 kbit/s

27.2 kbit/s27.2 kbit/s

13.4 kbit/s13.4 kbit/s

26.8 kbit/s26.8 kbit/s

40.2 kbit/s40.2 kbit/s

CS 2CS 2

Development of the GSM-data services

flow

Page 95: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing95

Enhanced Services - EMS (enhanced message service)

• Uses widespread existing infrastructure (SMS)• new Mobile telephones necessary• allows sending and receiving of messages with formatted texts,

melodies, graphics (32 x 32 Pixel) and animations (16 x 16 Pixel) – e.g. NOKIA

• new applications like Mobile Ticketing • tickets will be transferred to mobile phone like a bar code and

checked at the admission• EMS enables transition to MMS (multimedia messaging service),

which allows transmission of multimedia enriched messages over UMTS-Network (photos, parts of videos)

• MMS requires new network elements in the Infrastructure of the operators

Page 96: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing96

MMS - architecture

. . .

MMS Relay

MMS User Agent

MMS User Databases

MMS Server(e.g. E-Mail)

MMS Server(other service)

alien MMS Relay

SMTP

LDAP GSM-MAP or IS-41-MAP or TCP/IP

SMTP, HTTP, POP3,

IMAPv4

WAP or MExE (e.g. Java and TCP/IP)

HLR

MMS Server(e.g. Fax)

Based on materials from 3GPP, http://www.3gpp.org

Page 97: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing97

UMTS:Universal Mobile

Telecommunications System, 3G,3rd generation of mobile radio

Page 98: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing98

IMT-2000 - structure

source: www.UMTS-Report.com

• 3 systems - UMTS - CDMA2000 - UWC-136

• 2 core technologies - TDMA - CDMA

satellite- supported network expansion:- SW-CDMA: Satellite Wideband CMDA - SW-CDTMA: Satellite Wideband CDMA/TDMA (Hybride procedure) - SAT-CDMA: Satellite CDMA - ICO RTT: ICO Radio Transmission Technology

IMT-2000 family of radio interfaces :

– IMT-DS (Direct Spread)• UTRA-FDD (UMTS)

– IMT-MC (Multi Carrier)• CDMA2000, USA

– IMT-TC (Time Code)• UTRA-TDD (UMTS), TD-

SCDMA (Synchronous Code Division Multiple Access, China)

– IMT-SC (Single Carrier)• UWC-136, USA

– IMT-FT (Frequency time)• DECT

IMT-2000

TDMA

CDMA

individual carrier

multiple carrier

IMT-SC

IMT-FT

TDD

IMT-DS

IMT-MC

UWC-136 (EDGE)

DECT

UTRA-FDD

CDMA2000

UTRA-TDD

TD-SCDMA

FDD

IMT-TC

ICO RTT... Standard by ICO Global CommunicationsIMT ... International Mobile TelecommunicationsUTRA ... Universal Terrestrial Radio AccessUWC ... Universal Wireless Communications

In europeUMTS

Page 99: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing99

Worldwide frequency assignment for IMT-200• developed by ITU

PCS... Personal Communication SystemMSS...Mobile Satellite ServicePHS... Personal Handy-Phone System

Page 100: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing100

UMTS - Facts

• consideration: early 90ies

• Universal Mobile Telecommunications System, developed in the EU (ETSI: European Telecommunication Standards Institute)

• UMTS is the European implementation of IMT-2000 (International Mobile Telecommunications by the year 2000)

• Start of network expansion:

– in Europe: 2003 (some trials, e.g. British Telecom on Isle of Man, 2002)

– in the USA: 2005

– in Japan since 2000 : NTT DOCOMO

Page 101: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing101

1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200

GSM1800Uplink

GSM1800Downlink D

EC

T

FDDUplink

FDDDownlinkT

DD

TD

DMSS MSS

230 MHz frequency range for IMT-2000

• at FDD symmetrical spectrum is necessary, not at TDD (time slots at same frequency)

• gradual new assignment of wavebands

• depending on development of the need up to 300-500 MHz frequency range in 2008

Frequency award in Europe

source: www.UMTS-Report.com

MSS…Satellite- based

Page 102: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing102

• system general , worldwide roaming

• high data rates: 144 kbit/s mobile, up to 2 Mbit/s at local area

• fusion of different mobile radio communications-, wireless- and pager-systems into

one common system

• speech-, data-, and multimedia- information services independent of used network

access

• support of different carrier services:

– real-time capable/not real-time capable

– circuit switched/ packet switched

• Roaming also between UMTS and GSM and satellite networks

• Asymmetrical data rates in up-/downlink

Characteristics

Page 103: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing103

UMTS- Disadvantages

• Technology not yet perfect

• rent ability of pico cells („Hotspots“) not yet analyzed

• strong contention by WLAN

• increased radiation exposure

• high data rate only obtainable sometimes (High-Tech-network expansion, stationary and exclusive usage necessary!)

• because of high license costs high charges necessary (around double GSM-costs)

Page 104: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing104

UMTS - PerformanceTransmission Real- time (Video) Not Real-time (SMS etc.)

Bit error rate 10-3 … 10-7 10-5 … 10-8

Permitted delay 20ms … 300ms > 150 ms

~ 0 sec 10 sec 1 min 10 min 1 h

UMTS

GPRS

ISDN

PSTN

GSM

Web

Web

Web

Web

Photo

Photo

Photo

Photo

Photo

Mail

Mail

Mail Report

VideoReport

VideoReport

Video

VideoReport

source: Mobilkom Austria

Page 105: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing105

UMTS - Hardware• big color displays

• high resolution

• True Color

Page 106: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing106

UMTS- cell structure

Quelle: Mobilkom Austria

GatewayMobile

SwitchingCentre

3GMobile

SwitchingCentre

HomeLocationRegister

GatewayGPRS

SupportNode

Internet

customerIntranet

packet-switched

BTS BTS BTS BTS BTS BTS BTS BTS BTS

GSM - BSS UTRAN- UMTS Terrestrial Radio Access Network

Base Station Controller Radio Network Controller Radio Network Controller

Radioaccessnetwork

PSTN/ISDN

UMTS-Core Network

VisitorLocationRegister

circuitswitched

3G- ServingGPRS

SupportNode

Page 107: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing107

Zone1: In-building

“Pico cell”

Zone 2: Neighborhood

“Microcell”

Zone 3: Suburban

“Macro cell”

Zone 4: GlobalSatellite

Integration with the fixed network

Basic terminal

PDA terminal

Audio/visual terminal

UMTS: cell structure

“World cell”

Page 108: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing108

GlobalLokal

Regional

Home/Office

World Macro MicroPico

UMTS: hierarchical cell structureprinciple: - all neighbor cells use same frequency channel- only one waveband is necessary for cellular construction- further wavebands are necessary for hierarchical structure

expansion Data rate (kbit/s)

Max. velocity (mph)

Special features

World Cell global - no UTRAN, other technology!

Macro Cell Up to 1,24 miles 144 310 complete national UMTS support

Micro Cell Up to 0,62 miles 384 74 Greater cities, commonly used

Pico Cell > 60miles 2000 6,2! „Hotspots“ – e.g. airport, station

Page 109: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing109

Classification

Page 110: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing110

• Virtual Home Environment (VHE): offered

services are freely configurable, configuration

still exists in the whole network

• choose of service quality and also arising costs

• behave at bottlenecks (data rates, etc.)

configurable

• dynamic customization to connection

Service concept

Page 111: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing111

• one phone number for several devices (Call-

Management)

• subscriber localization e.g. with SIM-card

• call passing

• virtual mobility of fixed networks

UPT: Universal Personal Telecommunication Service

Page 112: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing112

Intelligent networks

• Implementation of basic services like subscriber localization billing etc.

• supply of value added service (Voice-Mailbox, etc.)

– possibility of easy, fast introduction of new services

– flexible service administration

– usage of services also from foreign network possible

– better control of service parameters through subscriber

Page 113: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing113

UMTS: basic network structure

• Access Network: base stations, responsible for radio contact to mobile

end devices

• Core Network (Fixed Network): responsible for structure of connections

• Intelligent Network (IN): responsible for billing, subscriber localization,

Roaming, Handover

Intelligent Network

Core NetworkAccessNetwork

User Equipment (UE)

Page 114: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing114

General reference architecture

UE UTRAN

Uu Iu

CN

• UTRA: UMTS Terrestrial Radio Access

– UTRAN (UTRA- Network) contains several radio subsystems, so called Radio

Network Subsystems (RNS) and contains functions for mobility management

– RNS controls handover at cell change, capacitates functions for the encoding

and administrates the resources of the radio interface

– Uu connects UTRAN with mobile end devices, so called User Equipment (UE), is

comparable with Um in GSM

– UTRAN is connected over Iu with the Core Network, comparable with the A

interface in GSM between BSC and MSC

– CN contains the interfaces to other networks and mechanisms for connection

handover to other systems

Page 115: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing115

The UMTS-radio interface UTRA (UMTS Terrestrial Radio Access)

• Two modes defined:– UTRA/FDD (Frequency Division Duplex)

• mainly in suburban areas for symmetrical transmission of speech and video

• data rates up to 384 kbit/s, supra-regional roaming• for circuit- and packet switched services in urban areas

– UTRA/TDD (Time Division Duplex)• mainly in households and other restricted areas (company's

premises, similar to DECT)• for broadcast of speech and video, both symmetrical: up to

384 kbit/s • also asymmetrical:

up to 2 Mbit/s

Page 116: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing116

UTRA/FDD

t

f in MHz

190 MHz

uplink

downlink

1920,9

1979,7

carrier 1

5 MHz

carrier 12...

2110,9

2169,7

carrier 1

carrier 12...

• puts wide- band- CDMA (W-CDMA) together with DSSS (Direct Sequence Spread Spectrum) as spread spectrum technique

• channel separation by carrier frequencies, spreading code and phase position (only uplink)

• ca. 250 channels for used data, data rates up to 2 Mbit/s• complex performance control necessary

Page 117: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing117

UTRA/TDD• puts wideband- TDMA/CDMA together with DSSS • sends and receives on same carrier (TDD)• ca. 120 channels for used data, data rates up to 2 Mbit/s• channel separation by spread code and time slots • less spreading than at FDD• precise synchronization necessary• lower demand for performance control

t

f in MHz

1900,1

1920,1

carrier 1

5 MHz

carrier 4...

2010,1

2020,1

carrier 5

carrier 6uplink downlink

Page 118: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing118

Extension Band 1 (worldwide similar) – partly terrestrial, partly satellite- based

Extension Bands (for a future market potential ..from 2005)

2520 2670 MHz470 862 2290 2300 2700 2900

Existing Nets

880 1885MHz

GSM,DECT

1675 1710MHz

satellite-based

1885 19801920 2010 2025 2110 2170 60 GHzMHz

MBSterrestrial

satellite- based

Frequency award for UMTS

Page 119: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing119

UMTS-licenses in Germany

• E-Plus Hutchison 8.394.492.363 €

• Group 3G 8.408.706.278 €

• Vodafone (Mannesmann Mobilfunk)8.422.920.192 €

• MobilCom Multimedia 8.369.848.095 €

• T-Mobil 8.478.344.232 €

• O2 (VIAG Interkom) 8.445.008.001 €17.08.2000: each license got 2 x 5 MHz packets, 60 MHz have been given away altogether, 150 MHz are available altogether

RegTP determined:- till end of 2003 25 % network coverage- till end of 2005 50 % network coverage

Page 120: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing120

Summary• introduced variants are the proposals, which will be

supported by Europe, Japan and partly by the USA • worldwide accessibility can be realized only with

multimode end devices • even in Europe combined

UTRA-FDD/UTRA-TDD/GSM- devices are necessary (those are realized by the identical frame time of 10ms at relatively low costs)

Page 121: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing121

Wireless Local Networks, WLAN

Page 122: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing122

Why do we need wireless LANs?

Advantages• flexibility• Ad-hoc-network realizable with less expenditure• No problems with cables Disadvantages• high error vulnerability on the transmission link in comparison to

Standard-LANs• National restrictions, no international standards at used frequency

bands (Industrial Scientific Medical (ISM)- Band)• security, costs

Page 123: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing123

Application areas

• networks in exhibition halls• hospitals• warehouses• airports• structure of networks in historic buildings• extension of existing wired local area networks

in offices, universities etc.

Page 124: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing124

Problems with the use of WLAN‘s

– physical problems• interference: band spreading • echo: use of special antennas • Hidden Terminal problem: use CSMA/CA

– data security• Wired Equivalent Privacy (WEP) service

further development WiFi (Wireless Fidelity), WPA (WiFi Protected Access)

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Standards• IEEE 802.11 (a,b,g ; optional e,h,i)

– frequency band 2,4 GHz, also in the 5GHz - band– data rates: 1 bis 11 Mbit/s (at present, later up to 20 (2,4 GHz) or

54 Mbit/s (5,4 GHz))– WiFi: Wireless Fidelity, certificate from the WECA (Wireless

Compatibility Allicance), secures the interoperability between the Radio- LANs and contains improved security mechanisms

• HomeRF• Bluetooth (IEEE 802.15)

– Frequency band: 2,4 GHz– Data rate: 1 Mbit/s; in the future also 20 Mbit/s– connection of peripherals

• HIPERLAN (ETSI) / Wireless ATM– frequency bands 5,15 / 5,30 GHz and 17,1 / 17,3 GHz– data rates: 24 Mbit/s or 155 Mbit/s– however no practical relevance

Page 126: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing126

IEEE 802.11b

• frequency:– 2,4 GHz frequency band, also called ISM (= Industrial Scientific

Medical Band), not regulated– 850 - 950 nm at infrared

• transmission power:– min. 1mW– max. 100mW in Europe (1W in the USA)

• reach:– of 10m (IR) to 30km or more with the help of special antennas

(directional antennas)

Page 127: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing127

Basic WLAN- structureAd-hoc-network:

AP

APAP

STA4 STA5

3 connected infrastructure networks:

AP - Access Point

Page 128: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing128

System architecture IEEE 802.11

Distribution System

802.x LAN

802.11 LANSTA1

Access Point

Portal

BSS1

Access Point

STA2STA3802.11 LAN

BSS2

ESS

Page 129: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing129

System architecture IEEE 802.11, concepts

• Station (STA)– device with 802.11- concurring interface

• Access Point– allows the access to the distribution system for registered stations and

secures accessibility of the stations also beyond the BSS

• Coordination Function (CF)– logical functional unit, which decides when a station can send

• Basic Service Set (BSS)– consists of several stations, that were controlled by an CF, e.g. BSS2

and STA2, STA3

Page 130: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing130

System architecture IEEE 802.11, concepts

• Distribution System– connects several BSS over access points and forms a logically larger

net

• Extended Service Set (ESS)– Radio networks, which are connected over Distribution System

• Portal– allows transition into other networks

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Overview• 802.11 is the most frequently used solution for wireless connection;

very strong distribution on the market• interesting future option: „Seamless Handover“ between GSM and

IEEE 802.11; supported by Cisco, Intel etc. (alternative to UMTS?)• higher data rates already standardized or in use

– 802.11a: physical layer at 5 GHz – Band, data rates up to 54 MBit/s– 802.11b: extension to physical layer for the 2,4 GHz – band, data rates

up to 11 MBit/s, products available – 802.11g: at present the industry works on an extension, shall allow the

up to 54Mbit/s in the frequency band around 2.4 GHz– Study Group 5GSG: examines the harmonization between IEEE 802.11

and ETSI HiperLAN– Task Group e: MAC functions for QoS-Management and to refine

improved safety functions, introduction of service classes etc.

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802.11 – Norms for WLAN802.11 Since end of 1990; RadioLAN; B=1-2 MBit/s; ISM-Band F=2,4GHz; low Interoperability

and bit rate!

802.11b 11MBit/s, actual Standard, existed NICs and APs; ISM-Band F=2,4GHz; possesses further sub-standards

802.11a Since 2000; competition with 802.11b; up to 54 MBit/s; F=5,1 GHz, correspond. national restrictions: in the buildings

802.11g Ratification March, 2003; first pre-standard products; ISM-Band 2,4GHz; up to 54 MBit/s;

802.11e Sub-standard; planed for end 2003; use of QoS-approaches; realization of multimedia applications/ Voice over IP over WLAN

802.11h Sub-standard / method for 802.11a; optional functionality – transmission power control of radio interface by national via RegTP prescribed norms; correspond. especially for Germany 802.11a or h

802.11i Sub-standard; security approaches for WLAN (encryption, authentication)

WPA WiFi Protected Access; Substandard; competition with 802.11i

802.11c Sub-standard; Method of Wireless-Bridging

802.11d Sub-standard; country specifics for 802.11b

802.11f Sub-standard; Routing between radio cells of different vendors by IAPP (Inter-Access-Point Protocol)

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Parameters Standards 802.11

802.11 802.11b 802.11a / h 802.11g

Frequency band, GHz

2,4 (ISM-Band) 2,4 (ISM-Band) 5,1 2,4 (ISM-Band)

Bit rate, MBit/s 1-11 11 54 54

Use field building, territory building, territory in the buildings building, territory

Deployment End 1990 actually Since 2000 Since March 2003

Available Hardware

Marketable NICs and APs

Marketable NICs and APs

Experimental operation

Pre-standard Products 

Data security WEP 64/128/256 bit WEP

802.11i - security approaches for WLAN (encryption, authentication);

WPA - WiFi Protected Access (competition with 802.11i)

QoS for multimedia-transmission

none none 802.11e (Ende 2003): use of QoS-approaches; realization of multimedia applications/ Voice over IP

Problematic • low bit rate• low

interoperability

low bit rate National restrictions

Pre-standard

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Mobile Communication and Mobile Computing134

Example: Lucent Wavelan 802.11b WLAN Card

• Wireless connection that acts just like a conventional Ethernet link

• Technical specifications:– 11 Mbps wireless connection – 40-bit WEP or 104-bit RC4 link layer encryption – Interoperability with other cards of IEEE 802.11b (i.e.

Cisco Aironet or the Apple Airport Card) – Tiny size - a PCMCIA card less than 1 inch – Cross-platform support (Linux, Mac, and Win*) – Very low cost (comparable to a PCMCIA 10/100

Ethernet card)

http://www.lucent.com/

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Mobile Communication and Mobile Computing135

Example: Globalsuntech 802.11b products

• Bit rates: 22/11/5.5/2/1 MBit/s per channel• WEP 64/128/256 Bit• Available devices:

– Card Bus– PCMCIA Card– PCI Card– Mini USB

• DSSS; selectable channels: – USA, Canada - 11 channels– Europe - 13 channels– Japan - 14 channels

• Sensitivity, range:– 80dBm for 22MBit/s– 92dBm for 1MBit/s

• Cross-platform support (Linux, Win*)

http://www.globalsuntech.com/

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Mobile Communication and Mobile Computing136

Further Scenarios (1)

Wireless Access Point (Hub Type)

Wireless PCPCs

Scenario 1: Wireless Access

LAN

WLAN

Page 137: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing137

Ethernet Hub

Wireless Access Point (Bridge Type)

Wireless PCs

Scenario 2: Wireless Bridging

Further Scenarios (2)

WLAN LAN

Page 138: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing138

Further Scenarios (3)

Wireless Access Point (Router Type)

Scenario 3: Share Wireless AP

Cable/DSL-Modem

Internet

WAN

WLAN

Wireless PCs

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Mobile Communication and Mobile Computing139

Cable/DSL- Wireless/ Wired Router

Wireless PCs

Scenario 4: Wireless/Wired Routing

Further Scenarios (4)

Cable/DSL-Modem

Internet

WAN

LAN

LAN

WLAN

Page 140: Mobile Communication and Mobile Computing

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UMTS vs WLAN

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Mobile Communication and Mobile Computing141

Mobility and data ratesmobility

Data rate [Mbit/s]

Source: http://www.netant.no

Bluetooth

0,1 1 10 100

2G

3G – UMTS

WLANLAN

Fixed

Walk

Vehicle

UMTS: better mobility, connectivity WLAN: higher data rates, more cheap, but no telephone

0,4

2,0

5,5

65,5

WLAN

UMTS (best support)

TDSL

ISDN

in minutes, trailer , 30 MBSource: Focus, 34/2002

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5200 5600 59005700 58005500540053005100

HIPERLAN HIPERLAN

High Speed wireless access

U-NII U-NII

Frequency [MHz]

License exempt.455 MHz

Sharing rules100 MHz

Unlicensed300 MHz

U-NII ... Unlicensed national information infrastructure

source: www.ist-mind.org, www.3gpp.org

WLAN- Spectrum Allocation

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Interworking UMTS/WLAN- User should be notified of any possible degradation- subscriber database could be shared, or separated in HLR/HSS (3GPP) or AAA (IETF) format

Three classes:- no coupling- loose coupling- tight coupling

UMTS/WLAN as completely independent

Contra:

Pro:- Rapid introduction- no impact on GSN nodes

- poor handover- no common database, billing

no coupling loose coupling tight coupling

UMTS/WLAN use same databasein AAA format

AAA ... Authentication, authorization, accounting

- poor handover

- good handling- no impact on GSN nodes

- improved handover performance

- HIPERLAN/2 have to support complete UMTS interface- feasible if operator have both networks

HIPERLAN/2 is connectedthrough UTRAN to UMTS,using special interface

Page 144: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing144

Data security in WLAN and UMTSData security for WLAN:• 802.11i

- new, additionally standards 802.11a/h and 802.11g

- complex solution for security- packet encryption- key distribution via RADIUS -Remote Access

Dial-In User Service - packet authentication- partial compatibility with IPsec- relevant against all attacks

• WPA - WiFi Protected Access − preliminary to 802.11i− properties similar to 802.11i− competition to 802.11i 

• WEP - Wired Equivalent Privacy - additionally to standard 802.11b, partially

obsolete!!!- users mobility between several Access-

Points, without re-configuration (roaming)- disadvantages:

- short key of 64 / 128 bit - different, partially contradictory statements to

offered security

Data security for UMTS:• IPsec

- Client/Server based, Clients and IPsec-Servers negotiate dynamic keys

- tolerant, relevant for key assignment to IP-subnets and against all Internet-attacks

- secrecy on the network layer: • IP-datagrams• TCP/UDP-segments• ICMP/SNMP-messages

- Encryption via DES, 3DES and 40-bit-DES

- authentication via - “IP Encapsulating Security

Payload" (RFC 2406, 1998)- “IP Authentication Header” (RFC

2402, 1998)

Page 145: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing145

HomeRF (Radio Frequency)

• competitive standard to IEEE 802.11• Up to 128 network nodes• Frequency jump in separations of 3MHz or 5MHz • Low costs and support of synchronous services: DECT

speech support• 2,4 GHz (FHSS), transition power max. 100 mW,• Shared Wireless Access Protocol (SWAP):

– hybrid protocol of DECT (TDMA) and CSMA according to IEEE802.11 (modified)

• up to 6 wireless fixed network connections• however sinking market shares in comparison with IEEE

802.11

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Mobile Communication and Mobile Computing146

HomeRF

• data rate 1-2 Mbit/s• 50 m reach within buildings• Supplier: e.g. Intel with ANYPOINT (wireless home

network)• future:

– HomeRF + Bluetooth: DUAL MODE SYSTEM (Symbionics)

+ ad-hoc possibly+ voice transmission

- today only few manufactures

Page 147: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing147

Wireless City Networking via 802.16

IEEE Wireless MAN/ ETSI Hiper MAN

Page 148: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing148

Wireless City Networking: scenarios

• new IEEE 802.16 standards can provide great regions with fast Internet services

• Use fields:– office materials shops– cafes– at the railway stations– to surf at the parks

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USA: Wireless MAN

• Wireless MAN: 802.16-version in USA

• Backgrounds: – competition to T-Mobile USA - mobile radio

network provider– great number of 802.11-Internet service

providers (ISP via Wireless LAN)– wide spread 802.11x – networks in the

country– via 802.11 provided approx. 2500 regions

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Mobile Communication and Mobile Computing150

Europa: Hiper MAN

• ETSI (European Telecommunications Standard Institute): – activities in the range of 802.16 –

development of Hiper MAN

• new marketable products: since July 2004 (according to announcement of Fujitsu Europe)

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802.16 / 802.16a

• Wireless MAN Standard 802.16– developed end of month January 2003– frequency bandwidth: 10 up to 66 GHz – reach: up to 50 km (30 miles)– data rate: up to 134 MBit/s– new 802.16x standards can provide great regions with fast

Internet service, momentary trial operation in Boston/USA (ISP via Wireless MAN)

• Start-Standard 802.16a– frequency bandwidth: 2-11 GHz– reach: up to 50 km (30 miles)– data rate: up to 70 MBit/s only– predominantly conceptualized for fast links of hotspots– can be used to establishment of private DSL-links– final operation inset: January 2005

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802.16a-Forum

• Members: – Airspan Networks, Alvarion, Aperto Networks,

Ensemble Communication, Fujitsu of America, Intel, Nokia, Proxim, Wi-LAN

• Aims: – to provide compatibility of 802.16a-products

among each other

Page 153: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing153

Conclusion: 802.16 vs 802.11802.11+ advantage:

– in spite of sharp competition to Mobile Radio (IMT2000/UMTS) 802.11x gained the mass market

– well-elaborated 802.11x (x = a, b, c, d, e, f, g, h, i, WPA)

− disadvantage: – existing bandwidth problems (at

most up to 54 Mbit/s)– reach at most up to 100m without

directional antennas

802.16+ advantage:

– covers approx. 50km (30 miles)– substitution via 802.16 as access

techniques possible– in future cost-efficient in

comparison to 802.11

− disadvantage: – averaged investment for leased

circuits amounting to 1000$ per location necessary

– sharp competition to Mobile Radio (IMT2000/UMTS): to occupy the market is for Wireless Networks more important as for Mobile Radio!

– final operation inset: planned January 2005 only

Page 154: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing154

(2) via Wireless MAN

Access Point

Wireless PCs

Scenario: fast Internet

Better than UMTS: future use scenarios of 802.16

(1) via ISDN, Modem, DSL

Internet

WAN

Wireless MAN 802.16

WAN

PC/LAN

WWW-Server/

Intranet-Firewall

up to 50 Km (30 miles)

70-134 Mbit/s

ISP via Wireless MAN

Page 155: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing155

Bluetooth

Page 156: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing156

Bluetooth - Facts• Harald Bluetooth was the King of Denmark in the 10th century • 1998 started from Ericsson, Intel, IBM, Nokia, Toshiba• Open Standard: IEEE 802.15.1• Generally for wireless Ad-hoc- piconets (Range < 10m)• Goal: not expensive One-Chip-Decision for radio/ wireless

communication networks• Use fields:

– Connection of peripheral devices– Support of Ad-Hoc-Nets– Connection of different networks

• Frequency band in IMS-Range of 2,4 GHz

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Mobile Communication and Mobile Computing157

Bluetooth

• Pico nets with up to 8 participants (ad-hoc) (one master, slaves)

• Scatter nets as an association of different pico nets• frequency hopping is used for improving of interception

safety and system robustness

Page 158: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing158

Bluetooth - properties

• Range:- 10 cm up to 10 m at 1 mW transmitting power

- up to 100m at 100mW

• Data rates:

– 433,9 kBit/s asynchronous-symmetrical

– 723,2 kBit/s / 57,6 kbit/s asynchronous-asymmetrical

– 64 kBit/s synchronous, voice service

– In future up to 20 Mbit/s (IEEE 802.15.3)

Basic set-up Bluetooth

2,4-Ghz- HF

Bluetooth-Baseband- Controller

Host-System

Page 159: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing159

Bluetooth-comparison

Source: http://www.okisemi.com

FUNCTION Bluetooth v1.1 IrDA Data 1.1 IEEE802.11 (WLAN)

Range w/o PA: 10 meter max. 1 meter max. 50 meter max.

Angle: omni-directional ca 30° omni-directional

RF Frequency Band:

ISM Band, 2.4 GHz Infrared Radiation ISM Band, 2.4 GHz

Mobility: mobile stationary mobile

Data rate: 721kBit/s 4MBit/s 2MBit/s

Security level: High Low High

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Bluetooth- functionalityStandby

Inquiry after unknownAddress

Page after unknownAddress

Send data connected

PARK HOLD SNIFF

MAC-Addressresigned

MAC-Addressavailable

t =2 m

s

t =2

ms

t =2 s

t =0,6 s

Not connected Standby

connection-status

active states

Low-Power-states

Page 161: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing161

Bluetooth – architecture (1)

Physical connection interface

connection between end devices

In hardware implemented !

connection between Hardware and upper protocol (only necessary, if L2CAP not implemented in Hardware!)

Applications

TCS,SDP,RFCOMM

L2CAP

LMP

Baseband

Radio

Dat

a

Dat

a

HCL

TCS …Telephony Control Protocol Specification SDP … Service discovery protocolRFCOMM … RF communication protocol (cable replacement protocol)LMP … Link Manager ProtocolHCL … Host ControllerL2CAP … Logical Link Control and Adaptation Protocol

Page 162: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing162

Bluetooth- architecture (2)Radio Layer

- work area: ISM-Band (2,4 Ghz) - Spread Spectrum Communication - Frequency Hopping- Technology- high error rate acceptability through CVSD-encoding at heavy micro wave load

Baseband- controls Radio- Layer2 Modes: - Synchronous, connection-oriented transfer (SCO)

voice connections need symmetrical, circuit-switched point-to-point-connections,

Master reserves two successive time slots (up- and downstream)

- Asynchronous, connectionless transfer (ACL) data transfers need symmetrical or asymmetrical, packet-switched point-to-point/multipoint- transfers, master uses polling

CVSD… Continuously Variable Slop Delta (Sprachkodierung)

Page 163: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing163

Bluetooth- architectureLink Manager Protocol

3 Functions

- Piconet management- link configuration- security functions

Logical Link Control and Adaption Protocol

Functions:- Mutiplexing (different applications can use connection between 2 devices

simultaneously)- Reduzierung der Paketgröße der Anwendungen auf akzeptable Baseband- Paket- Größe- Quality of Service

Page 164: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing164

Possible configurations

Master

Slave

Piconet Scatter net

Page 165: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing165

GSMBluetooth

possible configurations

• association of different pico nets• frequency hopping : jumps in k steps (k = 0…22 or 79) with Δf distances in ISM-band

a) Peer to Peer (or 1 Master and 1 Slave) b) Multi-slave (up to 7 "slaves" with 1 Master)

ScatternetPiconet

Master Slave 4 Master

Slave 3Slave 1

Slave 2

Slave 5

Piconet 1 Piconet 2Scatternet

Page 166: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing166

Bluetooth - Frequencies

Source: http://www.mobileinfo.com

- different frequencies around the world Goal: Harmonization of wavebands

Country Frequency range [MHz]

RF channels Multiplier

Spain 2445 – 2475fk = 2449 + k Δf k = 0,…,22

France 2446,5 – 2483,5fk = 2454 + k Δf k = 0,…,22

Japan 2471 – 2497fk = 2473 + k Δf k = 0,…,22

other Europe / USA 2446,5 – 2483,5fk = 2402 + k Δf k = 0,…,78

Δf… frequency distance between channels

Page 167: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing167

Bluetooth - Framestructure

Single slot frame Multi slot frame

source: http://www.intel.com

oneSlotPacket

Framefk fk+1

oneSlotPacket

Mas

ter

Sla

ve

625 µsone slot

three slot Packets

fk fk+1

oneSlotPacket

Mas

ter

Sla

ve

3- Slot-packets

625 µsone slot

Frame

Page 168: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing168

Bluetooth – security

source: http://www.intel.com

PIN PIN

E2 E2

Link Key Link Key

E3 E3

Encryption Key Encyption Key

Authentication

Encryption

user input(Initialization)

(possible)permanent storage

temporarystorage

- 128 Bit Key encryption and authentication- every device has own 48 Bit- address- over 281 .1012 devices can keep apart - low range (manipulation only local!)

Page 169: Mobile Communication and Mobile Computing

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Bluetooth – security Generic access:Three modes- non-secure- service level enforced security - link level enforced security

For Devices:two modes- trusted- untrusted

for Services:three modes:- services that require authorization and authentication- services that require authentication only - services that are open to all devices

Bluetooth device initiates security procedures before the channel is established

Sources: http://www.niksula.cs.hut.fi, Müller T., Bluetooth Security Architecture

Bluetooth is not secureenough for critical transmissions(billing etc.)

Page 170: Mobile Communication and Mobile Computing

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Bluetooth – applications (1)

• replaces perhaps infrared in the area of the coupling of peripherals completely

• „Intelligent Shop“– shop informs the buyer about special offers by mobile phone or handles

inquiries for offers in the individual halls

• Bluetooth-capable ticket machine– Payment over mobile telephone is carried out without contacts

• control of home appliances by mobile telephone• lower layers are developed further in the context of the IEEE 802.15

working group (WPAN - Wireless Personal Area Networks)– higher data rates, further frequencies, but possible interferences with

other systems

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Mobile Communication and Mobile Computing171

Bluetooth - applications

wireless connectionHeadset Handy

Page 172: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing172

HIPERLAN

HIPERLAN/1 wireless LAN (as extension to conventional LANs)5,15 - 5,25 GHz, ca. 20 Mbps, reach > 50 m, mobility < 10m/sdecentralized Ad-hoc net, no QoS-guarantee

HIPERLAN/2 wireless ATM-LAN (as extension to ATM and IP nets)5,15 - 5,25 GHz, ca. 20 Mbps, reach 50 m,

mobility<10m/scellular structure with base stations, ATM service classes

HIPERACCESS point-to-multipoint ATM connections5,15 - 5,25 GHz, ca. 25 Mbps, reach 5000 m, stationary/quasi-stationary, point-to-multipoint, ATM service classes

HIPERLINK point-to-point ATM connection17,1 - 17,3 GHz, 155 MBit/s, reach 150 m, stationary/quasi-stationary, point-to-point, ATM

source: ETSI RES 10, BRAN

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Assessment of HIPERLAN

• despite of some unique characteristics there are no products available yet, only single prototypes

• is planned as one of the alternatives for BRAN (Broadband Radio Access Network) in the Wireless ATM

• planned frequencies are originally not worldwide available (5,1-53GHz)

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Requirements:• wireless connection of mobile terminals to ATM-networks• compatibility to existing standards• existing networks should be easily upgradeable• guaranteed service quality properties which other wireless nets

don't offer• UMTS and WLANs don‘t offer any data rates >50 Mbit/sProblems:• ATM is conceived for high data rates• ATM is optimized on reliable media• applications should notice nothing of the wireless mode

Wireless ATM

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Wireless ATM: review• WATM still is standardization endeavors, no definite standards

approved • the WATM forum has tried to standardize as much as possible,

the WATM standard is relatively complex• WATM supports relatively many configurations:

– wireless Ad-hoc networks– wireless mobile end-devices: access to the network via radio

subsystem, similar to access-points– mobile end-devices: seamless handover between connected

terminals – mobile ATM-Switches (for planes, ships, trains etc.)– fixed ATM-terminals: conventional ATM– fixed terminals with radio access: comparable with line-of-sight

radio links• It is not arranged completely for which configuration also

products will exist

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Satellite-based systems

Page 177: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing177

Sample systemInter-Satellite Link (ISL)

GatewayLink (GWL)

Mobile UserLink (MUL)

Spot beams

Footprint

GatewayGround Station

User

PSTN, ISDN, GSM, ...Internet

Page 178: Mobile Communication and Mobile Computing

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Basics (1)

• satellites describe elliptical or circular orbit around the earth

• distance to the earth remains constant:

ZG FrmrRgmF 22/

f

ω

g

r

R

m

F

F

Z

G - Appeal of the Earth

- Centrifugal force

- Mass of the satellite

- Earth radius, 6.370km

- Distance of the satellite to the Earth’s center

- Grounding acceleration, g = 9,81 m/s2

- Angular frequency: /2/1,2 fTf- Cycle frequency of the satellite

(1)

Page 179: Mobile Communication and Mobile Computing

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Basics (2)

Formulae transformation:• F = m . a (by Newton)

• Fgrav = k . M . m / r2 (Gravitation between 2 point masses)

• mg = k . M . m / R2 (Appeal on the Earth surface =

Gravitation) • k . M = gR2

• FG = gR2 m/r2 = gm(R/r)2 (transformed)

• δt = 2 . (r-R) / c

Signal propagation delay

Satellite

Downlinkr-Rr-R

Uplink

Page 180: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing180

Basics (3)• (1) resolved to r gives:

• that means, the distance of a satellite to the earth's surface depends only on its cycle duration (special case T = 24h - > synchronous distance r=35.786 km)

3

2

2

2 f

gRr

(2)

Cycle duration [h]

10 20 30 40 x 106 m

4

12

20

velocity [x1000km/h]

Synchronous distance 35.786 km

Page 181: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing181

GEO (Geostationary Earth Orbit) ca. 36 000 km

MEO (Medium Earth Orbit) ca. 6000 - 12 000 km

Van-Allen-belts2000 - 6000 km15 000 - 30 000 km(no satellite use possible)

LEO (Low Earth Orbit) ca. 500 - 1500 km

HEO (Highly Elliptical Orbit)

Satellite system classes

Page 182: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing182

Base for Inmarsat

Principle:Satellit

Uplink Downlink

Geostationary Satellite systems

• Constant position to the Earth, 3 satellites cover complete earth (with the exception of the polar caps), satellites move synchronously to the Earth

• Simple solution, however large distance (36000 km), therefore high signal propagation delay, long life time of the satellites: ~ 15 years

• low data rates, large transmission power required

• problems:– on the other side of the 60th degree of latitude reception problems

(elevation)– because of a high transmission power unfavorable for mobile telephones– signal propagation delay too high (0.25 s)

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LEO- Systems• non-stationary satellites (LEO - Low Earth Orbit)• distance to the earth ~ 500 - 2000 km• shorter signal runtimes (5-10 ms), lower transmission power of

the mobile stations sufficing• however more satellites necessary, frequent handover between

satellites, approximately all 10 min.• examples: Teledesic, Globalstar• only low transmission power necessary, suitable for mobile

phone networks• Disadvantages:

– large number is necessary (50 - 200, or more)

– fast handovers within satellites are necessary

– short life time of the satellites because of atmospheric friction (5-8 years)

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MEO- Systems

• ~ 10000km, lower number of satellites necessary : ~12• slow movement: handover between satellites is hardly

necessary• cycle duration: 6h• high elevation enables coverage large, highly-populated

areas• Problems:

– signal propagation delay: 70 to 80 ms– higher transmission power is necessary– special antennas for small cells are necessary

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Service transitions in Inmarsat-C-service

Terrestrial stationBuffer memory

X.25Interface

Phone-InterfaceTelefax-Interface

Fixed network

Internet

X.25 Net Email System

modem PAD

data +maps

laptop fax

data +maps

Email

desktop desktop desktop

laptop

Inmarsat - C – End-TerminalGraphic table

Fax-Interface

MailBox

text

600 bit/s

600 bit/sInmarsatSatellite

L-Band 1,5/1,6 GHzRx/Tx (GPS)

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Satellites Height Data rate

Teledesic (planned) 288 (?) ~ 700 km 64 Mbit/s 2 / 64 Mbit/s

Iridium 66 (+6) ~ 780 km 2,4 / 4,8 kbit/s

Globalstar 48 (+4) ~ 1400 km 9,6 kbit/s

ICO 10 (+2) ~ 10 000 km 4,8 kbit/s

Inmarsat 5 geostationary 2,4 kbit/s

Orbcomm 35 LEO-stationary 57,6 kbit/s

Examples of satellite-based systems

Globalstar can transfer bi-directionally up to 144 Kbit/s, throughcombination of channels

Orbcomm - first commercial LEO–service worldwide http://Globalstar.com/

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Comparison of satellite-based systemsSatellite-based

systemGEO MEO LEO

Distance, km r = 35.786 km r-R=6000 –12000 km

r-R= 500 – 2000 km

Cycle duration, T 24 h 6 h 95 – 120 min

Signal propagation delay, t

0.25 s 70-80 ms 10 ms

Transmission power, W

10 5 1

Use examples Numerous systems, approx. 2000:•Sputnik (1957)•Intelsat 1-3 (1965, 1967, 1969)•Marisat (1976) •Inmarsat-A (1982)•Inmarsat-C (1988)

ICO 10+2 •Iridium (bankrupt, 2000) 66+6•Globalstar, 48+4/ 144 kBit/s•Teledesic (2003), 288/ 2-64 MBit/s• Orbcomm, 35

Data rate, kBit/s 0.1 – 1 10 1 – 64000

Life time, years 15 10 5-8

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Global Positioning System, GPS

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Overview• 24 satellites on the 6 orbits (20200 km, time of circulation =

12h)• 5 earth stations (Hawaii, Ascension Island, Diego Garcia,

Kwajalein, Colorado Springs)• Accuracy:

– so called P-Code for military applications: on ~6m accurately, partially 2,8m

– so called Selective Availability Mode, SAM (artificial degradation) for civil applications: < 100m (1.5.2000 disestablished)

• Functionality principle: Triangulation• GPS-receiver calculates distance to the satellite on the base of

Time of Arrival of the received signals• distances to at least three satellites enables the calculation of

position, a fourth satellite can be used for determination of elevation over zero

• official initiation 1995, testing since 1978

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Principle: TOA (Time of Arrival) / TDOA (Time Difference of Arrival)

Distance d,Signal Delay T Mobile Object

• synchronized clocks

• measurement of signal delay by speed of light between satellite and receiver, for instance T = 100 ms

• hence calculation of distance:d = T • c = 1 • 10-1s • 3 • 108 m/s = 3 • 107 m = 30.000 km

• calculation of spheres around each satellite

• the position is on the intersection point of three spheres

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Principles

• satellites send a signal composed of three components 50 times per second:– identification component: PRC (Pseudo Random Code), provides

satellite recognition and status information– position component: exact position of satellite– time component: time point, when signal is transmitted

• the time offset measured by the receiver is corresponding to the Time of Arrival, from TOA the distance is calculated

• for measurement of TOA of signals very accurate clocks are required

• the exact position of the satellites must be known

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Sources of errorsClocks• highly accurate atom clocks in the satellites• simple clocks in the receivers are calibrated via measurement of

a fourth satelliteSatellite position• satellite orbits are relatively stable and forecastable• deviations are measured by US DoD • deviations are transmitted as correction factor to the satellites

using the PRCMiscellaneous error sources• atmospheric faults• multi-path propagation

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Differential GPS, DGPS

• use of a stationary receiver as reference• position of this receiver is exactly known• the stationary receiver carries out position determination

and calculates correction factor from the actually obtained position on the base of deviations

• correction factor is delivered to the mobile receiver

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DGPS accuracy grades

• Accuracy under 10cm:– professional applications, for instance is interesting in

meterology and respectively for user of well-engineered software decisions (machine control systems etc.)

• Accuracy under 1m:– events mapping, control of machines, traffic control

systems, agriculture • Guaranteed accuracy under 10m:

– agriculture/ forestry, railway (wagon search service), car navigation (private/commercial)

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Galileo

• EU-Project for installation of European satellite navigation system

• initiation: prospective 2008• positioning accuracy: 45cm• 30 satellites• Approx. costs: 3,2 Billion €

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„ A system that both competes with and complements the American GPS system “ Galileo

ITS (Intelligent Transport System)

•based on a constellation of 30 MEO-satellites •ground stations providing information concerning the positioning of users •in many sectors usable:

─transport (vehicle location, route searching, speed control, etc.)─social services (e.g. aid for the disabled or elderly)─the justice system ( border controls)─public works (geographical information systems)

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Galileo -architecture

Service centres

GALILEO GLOBAL CONTENT

MEO Constellation

OSSNetwork

TTC

Navigation control & constellation management

OSSNetwork

...

User segment

UHF- S&RI-Band- NAV

Local Components

Local MS

Local MS

.

.

Data link

Data link

UMTS

External complementary systems

Regional Components

BSS network

.

.

COSPAS-SARSATground segment

BSS network

RMS network

GEO

EGNOS

i-bandi-band

Integrity determination

&dissemination

s-bands-band

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Broadcast Systems, Distribution Networks

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Overview

• special variants of asymmetric communication systems• HSCSD supports for instance asymmetric connections regarding to

data rate, also ADSL• WWW is the biggest representative of asymmetric communication:

– data volume of uplink (URLs) is much lower than downlink (complete HTML-pages)

• Problem of distribution systems: Sender can be optimized for a large quantity of receivers only, for instance videostreaming

• Examples:– DVB, Digital Video Broadcast

– DAB, Digital Audio Broadcast

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Principle of Distribution Systems

AC

BA

A

AAB

BBC

CCC

Time information sequence is optimized for expected access behavior of all consumers

t

Individual access sample of diverse consumers can more or less deviate from expected access behavior

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Digital Audio Broadcast, DAB• Audio-transmission in CD-Quality• Non-sensible towards interferences of multi-path-propagation• Use of SFN (Single Frequency Network) – i.e. all senders of

some broadcast-program are working on the same frequency as a rule

• Frequencies: UHF,VHF, for instance: 174-230 MHz, 1452-1492 MHz

• Modulation methods: DQPSK (Differential Quadrature Phase Shift Keying)

• Optionally COFDM (Coded Orthogonal Frequency Division Multiplexing) is used with several carrier frequencies inside some DAB-channel (its quantity is between 192 and 1536), 1,5MHz bandwidth for each channel

• FEC (Forward Error Correction)-mechanism for fault correction• Up to 6 stereo-programs by 192 kbit/s in the same frequency

band are transmittable• alternatively data can be transmitted with up to 1,5 Mbit/s

(responding to the used code rate etc.)

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Digital Audio Broadcast, DAB

2 Transport Mechanisms

• Main Service Channel (MSC):– Data, Audio, Multimedia– 2 Transport Modes: Stream Mode, Packet Mode

• Fast Information Channel (FIC):– Transport of Fast Information Blocks (FIB, 32 Byte) – control data for

interpretation of Data in the MSC, can be also used for services such as Traffic Dispatches, Paging etc.

• Audio-converting: PCM 48 kHz & MPEG2-Audiocompression

• High transmission rates by high velocities, up to 250 km/h, responding to distance from sender and error security class, use for instance in high-speed train

• MOT (Multimedia Object Transfer) protocol for data transmission

• Cyclic repeat and caching of data blocks

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Dynamic channel reconfiguration for DAB

Ensemble-Configuration

Temporarily changed Ensemble-Configuration

Audio 2192 KBit/s

PAD

Audio 3192 KBit/s

PAD

Audio 4160 KBit/s

PAD

Audio 5160 KBit/s

PAD

Audio 6128 KBit/s

PAD

Audio 1192 KBit/s

PAD

DataD2

DataD3

DataD1

DataD6

DataD7

DataD4

DataD8

DataD5

Audio 2192 KBit/s

PAD

Audio 4160 KBit/s

PAD

Audio 5160 KBit/s

PAD

Audio 1192 KBit/s

PAD

Audio 3128 KBit/s

PAD

DataD10

DataD11

DataD2

DataD3

DataD1

DataD6

DataD7

DataD4

DataD8

DataD5

Audio 796 KBit/s

PAD

Audio 896 KBit/s

PAD

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DVB - Digital Video Broadcasting

• 1991 ELR (European Launching Group) founded• Goal: joint digital Television System for Europe• Specifications: DVB-S, DVB-T, DVB-C• Frequency reaches: 200, 550, 700 MHz• Cell size: up to 60 km• Used data rate: ~38,5 Mbit/s• Velocity of mobile stations: up to 200 km/h• Central Unit: combined DVB-Receiver-Decoder (set-top-box)

– can receive DVB-Data via satellites, B-ISDN, ADSL…

– some transmission systems offer a feedback channel for Video on Demand etc.

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DVB - Digital Video Broadcasting• Different Quality Levels defined:

– SDTV (Standard Definition TV)

– EDTV (Enhanced DTV)

– HDTV (High DTV)

• Data transport:– User Data: MPEG2-Container (Data Transfer Unit) like DAB,

Container doesn’t define the type of data

• Service Information about MPEG2-Container-content:– NIT (Network Information Table): Information from a provider about

offered services and optional data for the receiver

– SDT (Service Description Table): Description and parameters for each service in the MPEG2-stream

– EIT (Event Information Table): Data about actual transmission status

– TDT (Time and Date Table): e.g. updating of DVB-receiver

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MPEG2/DVB-Container MPEG2/DVB-Container

MPEG2/DVB-Container MPEG2/DVB-Container

HDTVEDTV

SDTV

Single channel

(High Definition TV)

Several channels (Enhanced DTV)

Several channels (Standard TV)

Multimedia(data broadcasting)

Possible contents of DVB/MPEG2-Container

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DVB used as medium for asymmetric Internet-access

• Client sends data query to Provider, Provider transmits data to the satellite network, receiver obtains data via DVB-receiver

• Feedback channel can be phone network, for on-demand services

• Data rates:– 6 up to 38 Mbit/s downlink, 33 kbit/s up to over 100 kbit/s (ADSL) uplink

• Advantages:– data can be transmitted in parallel with TV– no additional costs for satellite provider– low priced for low-density populated areas

• Disadvantages:– all users need satellite antennas– only a minor part of the total bandwidth is usable– not suitable for high-density populated areas

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Internet

DVB–Card in the PC

Satellite provider

dedicated line (user-to-user)

Service Provider

Content Provider

DVB as medium for the asymmetric Internet-access

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3. Mobile Computing

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Layer 3

Mobile IP v4 & v6DHCP

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Mobile IP (Internet Protocol)

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Problem situation• computer mobility in heterogenic networks• relocation between different IP-subnets• Goal: transparent migration and localization,

compatibility to IP, no changes of existing routers• Idea: introduction of temporary/ actual IP-addresses

(also “care-of-address”, COA);• mapping of permanent to temporary IP-addresses

using localization technique

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Requirements to MobileIP according to IETF

Transparency:– mobile computer is permanently reachable via its

previous “home-address”– can change its network access point freely– can also communicate after coupling/uncoupling

Compatibility:– supports each layer below IP (also 1 & 2)– mobile computer can also communicate with each “non-

mobileIP”-computer– no changes to existing computer/routers

Security:– all registering messages must be authenticated

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IETF Mobile IP Goals/Restrictions

Minimization of overheads: – mobile connections are possibly wireless and have

limited band width– mobile connections have possibly higher error rate

Efficiency and scalability:– support of a large quantities of mobile computers– support of a theoretically Internet-wide mobility

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GlobalInternet

Home Subnet

Anywhere

Foreign Subnet

Home Agent (HA) Router

Foreign Agent (FA)

Correspondent Node (CN)

Architecture model

Mobile Node

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TermsMobile Node (MN) with permanent IP-address from Home

Subnet

Home Address permanent address of a mobile computer

Home Agent (HA) with knowledge of actual residence of all MNs from so called Home Subnet, like GSM-HLR

Care of Address temporary address of a mobile computer from Foreign Subnet

Foreign Agent (FA) for assignment of temporary IP-addresses (care of address) and packet forwarding to MNs currently residing in its subnet

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Log on via Foreign Agent

• Log on with a FA - Care-of Address (address of FA, is just an intermediate target for all MN- related packets, tunnel-end) or

• Application of a co-located Care-of Address (address from Foreign-Subnet, MN is tunnel-end itself), but reception of an Agent Advertisement Message with a set “R”-bit, i.e. the MN is forced to log on with FA itself, although it can operate autonomously

MN

HAForeignSubnet

HomeSubnet

1.) Registration.request

2.) relaying request

4.) Registration reply

FA

3.) relaying.reply

{grant, deny}

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Log on by Home Agent directly

HA

HomeSubnet

1.) Registration.request

2.) Registration.reply

{grant, deny}

MN

• MN uses co-located Care-of Address• MN is returned to Home Network and would like to log

on/off itself with the HA

Authentication:

• each mobile entity (MN, HA, FA) must be able to support a “mobility security association”, which is indicated via IP-address and SPI (Security Parameter Index).

• Mobile IP provides three different Authentication Extensions:

• Mobile - Home Authentication Ext.

• Mobile - Foreign Authentication Ext.

• Foreign - Home Authentication Ext.

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Addressing

Problem: For the receivers 2 addresses are necessary (permanent and temporary IP-address respectively home address and COA)

Methods of resolution:• Encapsulation

– IP in IP, standard method in MobileIPv4– minimal Encapsulation

• IP-Option (not supported by all implementations)

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IP in IP Encapsulation

• IP-source/target address of external/outer IP-Header defines the “end- points” of the tunnel

• IP-source/target address of internal IP-Header represents the actual packet sender respectively receiver

• Internal IP-Header isn't changed using “Encapsulator” (exception:

TTL)

IP HEADER

IP PAYLOAD IP PAYLOAD

IP HEADER

OUTER IP HEADER

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Routing (unicast)• Mobile Node:

– in Home Network it operates like each other Node– in Foreign Network it must search a Default Router using the

following rules:• FA COA:

– ICMP Router Advertisement-Part; – IP-source address of Agent Advertisements (lower Prior.)

• co-located COA: ICMP Router Advertisement for this address

• Foreign Agent:– FA must check by reception of tunneled packets whether

internal target address corresponds with one of the IP-addresses of Visitor List

– FA must route the received packets of registered MN’s!

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Routing (unicast) II• Home Agent:

– HA must intercept each packet for absent MN– in addition IP-target address of each incoming

packets is verified – if MN has no mobile coupling presently, the packets

sent to it must not be intercepted, MN is situated in Home Subnet and accepts packets itself or is off-line

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Routing (necessities)

• ARP (Address Resolution Protocol):– oriented to resolution of IP-addresses in physical (Hardware, Link Layer)

addresses (Ethernet: MAC-addresses of controllers)

• Proxy ARP:– Proxy ARP-reply is an ARP-reply, which can be sent instead of a host A

by other host B (with its hardware address)– Hosts, receiving this reply, associate the hardware-address of node B

with the IP-address of node A and send future packets for A to B

• Gratuitous ARP:– is an ARP-reply, which is sent from a host, to force other hosts to

update the records in their ARP-Caches– this ARP-reply contains the IP-address, which should be changed in the

ARP- Caches, as well as the hardware address which should be updated

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Routing - Scenario

• MN leaves Home Network• MN decides to register FA Care-of Address• Before Registration Request: MN re-sets a reaction on

future ARP-requests• Registration Request• contains and accepts HA Request, implements

Gratuitous ARP (IP-address MN ===> own hardware-address) and uses Proxy ARP to respond to ARP-requests corresponding to MN hardware address

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Triangle Routing

HA

FA

MN

CN

Foreign

Network

Home

Network

although CN is in the same Subnet like MN, packets are routed respectively tunneled via FA and primarily HA (possibly over half of terrestrial globe)!!!

CN ===> MN:

MN ===> CN:

Be routed conventionally via Default Router

Special case: Routing (MN & CN are in the same Subnet)

Relief (IPv4): Route Optimization

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Optimizations: Routing

Terms:• Binding Cache: table with Mobility Bindings of

MNs (on CN, can tunnel itself now)• Binding Update: message, contains up-to-date

Mobility Binding of a MN, particularly the Care-of Address

Procedure:• Update of Binding Caches

• Control seamless Handoffs between FA‘s

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Updating of Binding Caches

• Binding Cache of a CN: Care-of Address of one/several MN‘s, with respective Lifetime

• No Entry: non-optimal Routing, BUT: HA doesn’t only tunnel a datagram from CN, but also sends a Binding Update to it

• CN should generate/change Binding Cache-Entry only then, when trusted Mobility Binding received (Bind. Upd.) for corresponding MN (ergo: Secure CN <===> HA)

• If FA receives tunneled Packet for a MN that is no longer in Visitor List, then it must care that corresponding CN receives a Binding Update (Binding Warning to HA)

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Smooth Handoff between FAs

• Problem of Basis-MobileIP: MN is with a new FA, but the packets tunneled to old FA will be lost

• FA Smooth Handoff: MNs are informed via new FA (packet can be forwarded)

• also Packets of hosts with non-up-to-date entries in Binding Cache can be forwarded now from old FA to the new FAs

• Previous Foreign Agent Notification Extension enables to prompt the new FA to inform the old FA (Binding Update Message)

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MobileIP v4 & v6 in comparisonMobile IPv4 Mobile IPv6

Optimal Routing, only if MNin the Home Network. (Otherwisenon-efficient „Triangle“-Routing)

Optimal Routing is generallypossible, if CN knows the Care-of Address

Routing

HA is a possible bottleneck, because all trafficto the MN is processed over it

HA is load essentially reduced, because CN‘s can just directly communicate with mit MN‘s

Bottle neck

Authentication is prescribed only by Registration and then also between HA and MN only

Authentication and encryption are possible anywhere, becausethey are supported from IPv6

Security

Used FA‘s / HA‘s must not be off-line

Short-time failure/re-configuration of HA is mastered thanks toAutomatic Home Agent Discovery.IPv6 is essentially simpler to upgrade, therewith also Mobile IPv6

Robustness

No good performancedue to IPv4-requirementsand non-optimal Routing

Essentially better due to requirements from IPv6 (uniform Headers, less Over-heads) and optimal Routing

Performance

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Assessment

• Mobile IP enables the unlimited accessibility/roaming of mobile computers using perpetuation of their addresses and step-less transfer between subnets

• Particularly necessary for applications without “pull”-semantics (for instance, distributed applications with mobile users, videoconferences, VoIP)

• Keeping of permanent addresses are also important corresponding to Firewalls etc. in the case of call semantics

• Successive availability in the form of products

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Dynamic Host Configuration Protocol (DHCP)

Properties:• permits automatic

configuration (IP-address, subnet-mask, router, DNS-Server, ...) and therewith integration of (mobile) computers

• Client/Server-Model• Lease Concept• Relevant for

management of Care-of-Addresses

Server A Server BClient

DHCPDISCOVER DHCPDISCOVERDeterminationof configuration DHCPOFFER DHCPOFFER

Selection of a configuration

DHCPREQUEST

(reject)

DHCPREQUEST(options)Confirmationof configuration

DHCPACK

Determinationof configuration

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DHCP Assessment

• no secure mechanisms standardized• no standardized communication (signalization,

for instance information exchange about managed address areas) between DHCP-servers

• good base for allocation of co-located COAs in MobileIP

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IPsec: Network security

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Mobile Communication and Mobile Computing234

IPsec: Security on the network layer (1)

• IPsec - IP Security Protocol – new developed protocol from TCP/IP-Stack, related to the IPng - Group

• IPsec uses: – encryption services -> DES, TripleDES and 40-bit-DES between

hosts at a VPN (virtual private network)– specification for Internet Key Management Protocol (IKMP),

based on ISAKMP/Oakley (1998, Internet Security Association and Key Management Protocol - ISAKMP)

• IPSec-tunnels – encapsulation of TCP/IP-data via the ESP/AH- headers:– Developed by S.Kent, R. Atkinson „IP Encapsulating Security

Payload" (RFC 2406, 1998) and "IP Authentication Header" (RFC 2402, 1998)

– relevant for key assignment to IP-subnets

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IPsec: Security on the network layer (2)

• Secrecy on the network layer: a sending host encrypts/authenticates data encapsulated in the IP-datagrams

– TCP/UDP-segments– ICMP/SNMP-messages

• Authentication on the network layer: – target host can authenticate source IP-addresses

• Basic protocols:– Authentication Header (AH) Protocol– Encapsulation Security Payload (ESP) Protocol

• AH and ESP both requires target and source Handshake-Routine:– establishment of a logical channel via network layer, called Service Agreement

(SA)– each SA is unidirectional

• Distinctly determined via:– security protocol (AH / ESP)– source IP-address– Con-ID of 32 Bit

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Encapsulation Security Payload (ESP) Protocol

• offers secrecy, host authentication and data integrity• data, ESP trailers encrypted• next header field is a trailer in the ESP• ESP- authentication field is similar to AH- authentication field;

protocol field = 50

ESP-AuthESP-Auth

Protocol = 50

ESP-TrailerESP-TrailerTCP-/UDP-SegmentTCP-/UDP-Segment

authenticatedencrypted

ESP-HeaderESP-HeaderIP-HeaderIP-Header

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Authentication Header (AH) Protocol• offers host authentication and data integrity, but no secrecy• AH headers inserted between IP-Header and IP-data field; protocol

field = 51• participated routers process datagrams as usually

AH-Header consists of:• Con-ID• authentication data: signed message digest calculated via original

IP-Datagram, offers authentication of source hosts and data integrity

• next header field is specific data type (TCP, UDP, ICMP etc.)

TCP-/UDP-SegmentTCP-/UDP-SegmentAH-HeaderAH-HeaderIP-HeaderIP-Header

Protocol = 51

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Layer 4

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Mobile Communication and Mobile Computing239

Problems of conventional protocols

Problem:• Loss of packets on the radio channels with higher bit-

error rate (BER) results in frequent retransmissions of packets and therewith in further efficiency loss

• TCP-Protocol uses so called “Slow-Start”-mechanisms: window size is reduced by significant packet losses; this is reasonable for fixed networks, to react on overload, but not for packet losses due to higher BER

• limited suitability of conventional transport protocols for mobile communication!

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Conventional protocolsCongestion Control:

• packet loss as a rule, in fixed networks occurs only by overload of several components

• reducing of transmission rate

Slow Start:

• sender calculates a traffic window size

• start with window size 1

• exponential growth till to Congestion Threshold

• then linear growth

Fast Retransmit / Fast Recovery:

• If ≥ 3 DUPACK (duplicate ACK) are received

-> sender informs about packet losses and repeats missing packets

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Resulting problems in mobile environment

• packet losses due to transmission errors are wrongly interpreted as traffic jam (Congestion)!

• > Slow Start is also wrong• > Ideally the packets lost due to transmission

errors are simply repeated (no effects on Congestion Control)

• great variances of Round-Trip-Time

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Scenario

Mobile Host

Fixed HostAccess Point 1

Access Point 2

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SolutionsSender- transparent:• to hide the packet losses transparent to the sender• transmission repeat via Access Point

– on layer 2

– on TCP-layer

Wireless-aware sender:• sender understands the reason of packet loss• explicit notification of senders• sender tries to determine the reason of loss

Where will be the modifications carried out?:• only by the sender• only by the receiver• only on the transient node (Access Point)• combinations

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– Separation between transport functionality in the fixed network respectively in the mobile network:

– MobileTCP is specially optimized (up to 100% of efficiency improvement possible)

– system-internal TCP-Handovers are necessary, however transparent for fixed computer (Workstation)

Work-station MSR

MSR

Mobilenode

Mobile Support Router

TCP

Fixed networkMobile TCP

Mobile network

TCP-Handoverby relocation of mobile node

Solution “Split Connection“

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Example of I-TCP (indirect TCP)• separation of TCP-connection at the Access Point• optimized TCP over the wireless Link (not absolutely necessary)• no changes of TCP for the fixed network• transparent for Fixed Host • loss of End-to-End-semantics

Mobile Host

Fixed HostAccess Point 1

„wireless TCP“ „standard TCP“

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Example of I-TCP

• Mobility: status and buffer transfer

Mobile Host

Fixed Host

Access Point 1

Access Point 2

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I-TCP Assessment

+ no changes in the fixed network+ the errors in the wireless part aren’t propagated to the fixed network+ both parts can be optimized independently + relatively simple: „wireless TCP“ concerns one Hop only+ the properties of wireless networks (bit-error rate, delay time) are

known, therefore fast retransmissions are possible ─ loss of End-to-End-semantics─ additional costs (computation time, storage place) concerning the

Access Point─ high delay times with handover caused by buffering of data by

Access Point─ IT-security mechanisms must be adapted

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Example of Snoop• transparent extension of Access Point from sender’s viewpoint• Access Point listens to the traffic (snoops) and filters the ACKs• buffering of data, are sent to the mobile computer• after losses of packets in the wireless network a direct

retransmission takes place between Access Point and Mobile Host• Access Points send NACK after packet losses of MH

Mobile Host

Fixed HostAccess Point 1

TCP

Buffer„local retransmission”

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Snoop Assessment

+ maintenance of End-to-End-semantics+ modifications only at the TCP-Stack of Access Points+ errors in the wireless part can be corrected locally+ Soft State

+ no status transfer at new Access Point is necessary

+ change is possible, also if the new Access Point possesses no Snoop

• no complete transparency of wireless connection• handling of NACK requires the modifications of MH• IT-security: encryption can prevent an access to TCP-Header (most

of the up-to-date approaches use End-to-End-encryption!)

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Higher Layers and Services

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Wireless Application Protocol - WAP

Based partially on the materials of WAP-Forum

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WAP – Standard Overview

• Goal: Fusion of Internet-Technologies and mobile radio, creation of new innovative services

• standardized by WAP-Forum (http://www.wapforum.org), initiated by Ericsson, Nokia, Motorola

• specifies application environment and protocols for mobile end-devices such as radio phones, PDAs, pagers

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Why WAP?• Mobile radio networks and mobile phones

possess special properties and requirements– Display: sizes and presented colors, numerical

keyboard, lower processor performance and storage capacity ...

– Networks: low data rates, high delays and costs

• WAP offers the use of several carriers– TCP/IP, UDP/IP, USSD, SMS, ...

USSD - unstructured supplementary service data (GSM)SMS - short message service (GSM)

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Why WAP ?• WAP-architecture has a modular organization• the modules build together a complete Internet-protocol-stack• WML-contents can be queried by HTTP-request-messages• WAP uses XML (eXtensible Markup Language)-Standard as

well as optimized contents and protocols• user interface of conventional end-devices is supported by

WML-components– enhances acceptance by users

• WAP uses conventional HTTP-Servers– existing development strategies are applicable in the

future (common gateway interface - CGI, active server pages - ASP, netscape server API - NSAPI...)

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Why HTTP/HTML doesn’t suffice?

Big pipe - small pipe syndrome

<HTML><HEAD><TITLE>NNN Interactive</TITLE><META HTTP-EQUIV="Refresh" CONTENT="1800, URL=/index.html"></HEAD><BODY BGCOLOR="#FFFFFF" BACKGROUND="/images/9607/bgbar5.gif" LINK="#0A3990" ALINK="#FF0000" VLINK="#FF0000" TEXT="000000" ONLOAD="if(parent.frames.length!=0)top.location='http://nnn.com';"> <A NAME="#top"></A><TABLE WIDTH=599 BORDER="0"><TR ALIGN=LEFT><TD WIDTH=117 VALIGN=TOP ALIGN=LEFT>

<HTML><HEAD><TITLE>NNN Interactive</TITLE><META HTTP-EQUIV="Refresh" CONTENT="1800, URL=/index.html">

InternetHTTP/HTML

Converting to binary format

Mobile radio networks

<WML><CARD><DO TYPE="ACCEPT"><GO URL="/submit?Name=$N"/></DO>Enter name:<INPUT TYPE="TEXT" KEY="N"/></CARD></WML>

010011010011110110010011011011011101010010011010

WAP

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WAP-overviewWAP-standard defines:• Environment = Wireless Application Environment

(WAE)– WML (Wireless Markup Language) micro-browser– WMLScript virtual machine– WMLScript standard library– Wireless Telephony Application (WTA) Interface– Contents = WAP Content Types

• Layer architecture– Wireless Session Protocol (WSP)– Wireless Transaction Protocol (WTP)– Wireless Datagram Protocol (WDP)– Interface definitions for mobile network

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Comparison: Internet/WWW and WAP

HTMLJavaScript

HTTP

TLS - SSL

TCP/IPUDP/IP

Wireless ApplicationEnvironment (WAE)

Session Layer (WSP)

Security Layer (WTLS)

Transport Layer (WDP)

other services andapplications

Transaction Layer (WTP)

Carrier: SMS USSD CDMA CDPD etc..GPRS

InternetWireless Application Protocol

SMS - Short Message Service (GSM), GPRS - General Packet Radio Service (GSM II+), CDMA - Code Division Multiple Access, CDPD - Cellular Digital Packet Data

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Wireless Application Environment - WAE

• environment for distributed applications with specific reference to low-performance end-devices with limited operation comfort and mobile radio networks

• Goals:– network-independent application environment– optimized for application in mobile radio systems– Internet, i.e. WWW–programming model– high interoperability level

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WAE – abstract network architecture

GatewayClientNetwork

Application

WSP/HTTP Request {URL}

WSP/HTTP Reply {Content}

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Constituents• Architecture

– Programming model– Browser, Gateway, Content Server

• WML– as page markup language

• WMLScript– as scripting language

• WTA– offers access to phone services

• Content formats– sets free-defined formats: bitmaps, phonebook records,

dates ...

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Options

• User Agent Profiling– to user, end-device, ... adapted contents

• Push-model– network initiates delivery of contents

• Options for performance improvement– Caching, ...

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Sample: WAP-Gateway

Web Server

Contents

CGIScripts

etc.

WM

L D

ecks

,W

ML

-Scr

ipt

WAP Gateway

WML Encoder

WMLScriptCompiler

Protocol adapter

HTTPWSP/WTP

Client

WML

WML-Script

WTAI

etc. WA

E U

ser

Ag

ent

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Sample: WAP - Application Server

Contents

Applicationlogic

WM

L D

ecks

,W

ML

-Scr

ipt

WAP Application Server

WML Encoder

WMLScriptCompiler

Protocol adapter

WSP/WTP

Client

WML

WML-Script

WTAI

etc. WA

E U

ser

Ag

ent

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Wireless Markup Language - WML(1)

HDML - Handheld Device Markup Language, W3C - World Wide Web Consortium, XML - eXtensible Markup Language

• HTML-like page markup language– different font styles are available, tables

and graphics too, but limited • based on W3C-XML• uses HTML and HDML-elements• Deck/Card-metaphor

– interactions-/selection possibilities are separated in Cards

– navigation (anchor: #) takes place between Cards

– Deck-stack corresponds to a WML-file

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Wireless Markup Language - WML(2)

• explicit navigation model between Decks– Hyperlinks– Events from user interface– History

• variables and status-management– variable status can tell about validity of a stack

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WML– text styles

DeckCard

<wml> <card id=“Card1” title=“Text Styles”> <p align="left">

<i>italic</i>, <b>bold</b>,<br>

<big>big</big>,<small>small</small>,<u>underlined</u> </p> </card></wml>

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WML-example (1)

Selectedinput

Script call

Variables

Navigation

<wml> <card id=„Card1" title=„Currency" newcontext="true"> <p> Amount: <input format="*N" name=„amount" title=„Amount:"/> From: <select name=“from“ value=" USD“ title=„From:"> <option value="EUR">Euro</option> ... <option value="USD">US Dollar</option> </select> To: <select name= ... <br/> = <u>$(conv)</u> <do type="accept" label=„Calculate"> <go href=“bsp.wmls#convert('conv', '$(from)','$(to)',$(amount))"/> </do> <do type="help" label="Help"> <go href="#card1_help"/> </do> </p> </card> ...

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WML-example (1): Processing

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WML-example (2)

Events processing

<card id="card1_help" title="Help"> <onevent type="onenterforward"> <go href="bsp.wmls#getInfoDate('date')"/> </onevent> <p> Currency exchange rates stem from Federal Reserve Bank of New York and are from $(date). <do type="prev" label=„Back"> <prev/> </do> </p> </card></wml>

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WMLScript-overview (1)

• scripting language, similar to JavaScript– procedures, loops, conditions, ...– optimized for devices with low storage capacity and

CPU-performance

• integrated with WML, enables:– reducing of network workload– validation of inputs– access to vendor-specific APIs– programming of conditional logic

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WMLScript-overview (2)

• Bytecode-based Virtual Machine– stack-oriented design– ROM-able– designed with regard to simple, less work-expensive

implementation

• Compiler in network– better utilization of network capacity and end-device

storage

• Standard library– basic functionality for processing of strings, URLs, ...

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WMLScript-example

Procedures

Variables

Statements

extern function getInfoDate(varName){ WMLBrowser.setVar(varName,„June,3,2002"); WMLBrowser.refresh();}extern function convert(varName,from,to,amount){ var multiplier = 0.0; ... if (from == „EUR") { ... if (to == „EUR") multiplier = 1.0; else if (to == „RUR") multiplier = EUR_RUR; ... } else if ... WMLBrowser.setVar(varName,returnString); WMLBrowser.refresh();}

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Wireless Telephony Application - WTA (1)

• offers mechanisms for applications in field of telephony

• primary focus: operators/providers and vendors

• security and trust are the emphasis• WTA Browser

– using improvements of standard WML/WMLScript- browsers

– own interface WTAI (... Interface)

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Wireless Telephony Application - WTA (2)

• WTAI contains:– call control, messaging, interface to phonebook,

events processing...

• own Client/Server-interaction model – event signalization...

• security via separation– browser and port separated

• WTAI in WML and WMLScript available

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WAE content formats

• WAE defines uniform formats– visit cards, so called IMC vCard Standard– dates, IMC vCalendar Standard– graphics, WBMP (Wireless BitMaP)– compiled WML, WMLScript

• Goal: Interoperability

IMC - Internet Mail Consortium

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WAP layer architecture

Wireless Session Protocol (WSP)

Wireless Transaction Protocol (WTP)

Wireless Datagram Protocol (WDP)

CarrierService A

CarrierService B

CarrierService C

Carrier DService D

Physical Layer Air Link Technology

Carrier AAdaptation

Carrier BAdaptation

Carrier CAdaptation

Wireless Transport Layer Security (WTLS)

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Wireless Session Protocol

• supports Client/Server context (shared state), optimization of content transmission

• offers semantics and mechanisms, which are based on HTTP

• and improvements for use in mobile radio networks with low-performance end-devices

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WSP overview (1)• HTTP elements:

– extensible request/reply methods– extensible request/reply headers– uniform contents– composed objects– asynchronous requests

• Improvements:– binary encoding of headers– session headers (Client & Server)– confirmed and unconfirmed network-initiated delivery (Push)

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WSP overview (2)• Improvements corresponding to HTTP:

– negotiations of supported characteristics– session suspend/resume– multiple complete asynchronous transactions– connectionless service

• Why doesn’t HTTP suffice?– no compact encoding– insufficient negotiations– Push doesn't exist

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Characteristics

• message size• protocol options

– Confirmed Push Facility/ Push Facility (unconfirmed)– Session Resume …

• maximum outstanding (unanswered) requests• Header Code Pages (known field names in the

protocol headers are separated into pages)• ...

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Suspend/Resume

• Server knows, when a Client accepts data (Push)• multi-carrier devices• dynamical addressing• enables release of carrier resources

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Wireless Transaction Protocol (WTP)

• Goal:– efficient request/reply-based transport mechanism for mobile

radio networks and low-performance end-devices

• Properties:– robust data transmission– no explicit connection set up and connection release– data are transmitted already with the first packet– packet oriented– abortion-function for outstanding (unanswered) requests

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Wireless Transaction Protocol (WTP)

• Properties:– supports concatenation of messages– further WTP features:

• repeated transmission due to packet loss (selective)• fragmentation• port numbers (UDP)• flow control

• Transaction = Interaction between Initiator and Responder

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WTP – transaction classes (1)• Class 0:

– non-robust datagram-service– for instance for Push during a session– shouldn’t substitute WDP– the transactions are closed after transmission of

Invoke

• Class 1:– robust datagram-service– the transactions are closed after transmission of

Invoke

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WTP – transaction classes (2)

• Class 2:– robust datagram-service with robust Invoke- and

robust Result-messages– the transactions are closed via the Initiator after

answer confirmation of the Responder

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Wireless Datagram Protocol (WDP)

• provides connectionless, non-robust datagram-service

• is substituted by UDP, if IP the a carrier• re-adaptation to the carrier takes place in the

Adaptation Layer• supports port numbers

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Wireless Transport Layer Security (WTLS)

• enables secure connections, uses protocol elements of known, secure Internet-protocols (TLS)

• provides mechanisms for encryption, strong authentication, integrity and key management

• corresponds to guidelines of national authorities

• offers end-to-end security

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WAP & Security

• WTLS (Wireless Transport Layer Security) offers only security via encryption of transmitted data (Grade #1) presently, similar to TLS, only communication trustiness is protected

• Grade #2 supports Server- and Client-certificates, for instance via additional chip-cards in mobile phones, so called WIM - Wireless Identification Module

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UBS (Switzerland)• data with WTLS class 2, 128 bit 3DES encrypted• UBS authentication against mobile phone via certificates with a

key size of 1024 bit• participant authentication against UBS via WAP similarly like via

Internet with agreement number, password and list-number• automatic connection release (Timeout) embedded

– after ten minutes without interaction participant is demanded to re-authenticate with password und list-number input

Deutsche Bank (Germany)• WTLS (Wireless Transport Layer Security)• end-to-end-encryption• data encryption already at the mobile phone• decryption at the server

WAP & Security

Sources: UBC.ch,db24.de

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WAP-Gateway Web-Server

Java-Servlet-APIWML

HTTP

Dir-X-wap

Dir-X-Servlet LDAP-Client

Server

LDAP/X.500-Directory-Service

LDAP

Server

WML-pages Profiles

WAP-example: access to enterprise data

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WAP-example: access to enterprise data

Example: Siemens Dir-X Meta-Directory Service as a base of a corporate information pool

• software-package consists of Directory Server (Dir-X-Metahub) and several Clients, is completely LDAP v3 compatible, based on X.500

• 2 Gateways outwards: Dir-X-Web and Dir-X-wap• secure access also via WAP available, because all security

properties of Directory-Servers are handed-on to mobile user• registration via phone number and password, the

authorizations/licenses are deposited within the system in user profiles

• Java-Servlets built the kernel components of WAP-connection Dir-X-wap-Server:• Servlet-components undertake communication with the Web-Server• LDAP-Client provides data exchange between the Dir-X-wap-Server

and the directory service

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WAP-example: access to enterprise data

Dir-X-Wap-Application:• consists of a set of WML-pages containing DSL• Dir-X-Servlet parses DSL-commands• 2 configuration files for an application necessary:

– Global Profile: contains information for the Servlet– Application Profile: stores the data that are necessary to

execution of WAP-application• In principle, each Web-Server is usable with the product,

it must only support the Servlets

DSL: Directory Script Language; Language for processing of directory requests from Web- or WML-pages and for representation of obtained results in WML or HTML, contains the language elements for LDAP-access

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WAP-examples

• Bond/Security-Order processing: Consors, Advance Bank, Deutsche Bank

• Mobile “Yellow Pages” – Orange Telecom• Mobile Timetable: wap.hafas.de• Mobile Auctioning: wap.yahoo.de, wap.ebay.de• Mobile „Last Minute Bargain “:

– 12snap at Vodafone, presently also with WAP

• Mobile marketplaces/stock exchanges (Mobile Brokerage):– http://www.heizoelboerse.de/– http://www.amazon.de/

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Bond/Security-Order

•Mobile Banking

•Mobile Brokerage

WAP-example: Bond/Security-Order

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Private Banking-> Login page

Other services ... Lufthansa, Sixt, etc.

WAP-example: Bond/Security-Order

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WAP-example: Bond/Security-Order

Main menu• Brokerage ...

Bond/security info

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WAP-example: Bond/Security-Order

Order book

• Status of bond transactions

• Executed and deleted orders are indicated in the order book for some days more

• Partial execution of some order is presented as one open and one executed partial order in the order book

• Details to an order could be indicated via dial-up of correspondent Links

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Portfolio review• Bond/security depots

WAP-example: Bond/Security-Order

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WAP-example: Bond/Security-Order

Brief queries

• exchange rates of Bonds/Securities with a delay of approx. 15Min

• search criteria– Bond/Security-ID and/or

– Bond/Security-name

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WAP-example: soccer/football score

source: http://www.wapgoal.com

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Further WAP-examples

soccer/football scores:

http://wap.goal.com

auctioning:

http://wap.12snap.com

miscellaneous:

http://wap.yahoo.com

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Input the address

...wait ...

WAP-example: timetable service

Input

-> English -> Query...

…wait ...

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Input the start & target

railway stations

...Dresden,

…Hannover

...scroll …

WAP-example: timetable service

Input

..date, time....

…scroll …

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After input …

search...

..wait..

WAP-example: timetable service

Selection of train connections with departure platform ...earlier/later...

then probably ->

END

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For comparison: PC-timetable service

Details

Options

PC-timetable service is still detailed!

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WAP-result• WML doesn’t bring whole Internet’s diversity to a mobile phone

• there are no satisfactory rate models at the moment; the data-rates are too low even with GPRS

• limited input and selection possibilities require a reconsidering of interaction semantics, WAP isn’t oriented for many applications, for instance catalogs with a large selection -> PDAs, appliances, voice input and -recognition

• with introduction of data services with higher data-rates WAP could lose its relevance possibly -> XHTML

• however WAP means a first step towards independence from PC by access to Internet contents -> multi-dimensional distribution channels for information

• WAP means the start for creation of a formidable user population (potentially all mobile radio participants)!

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WAP-Improvements: WAP2.0 (1)• New version

– Internet-based data services on mobile phones – approved by WAP Forum mid-2001– oriented to GPRS and 3G cellular/UMTS

• Useful services at WAP2.0 devices– color graphics and Pictograms– location-specific content, navigational functions and user-friendly

menus– animation representations and streaming media– Multimedia Messaging Service (MMS)– large-file downloading (music)– synchronization of user information with personal information

manager software on a desktop PC in a remote location

Source: http://www.wapforum.org

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WAP-Improvements: WAP2.0 (2)

• WAP 2.0 builds upon the latest Internet standards: – XHTML, TCP/IP, HyperText Transfer Protocol (HTTP/1.1) and

Transport Layer Security (TLS)– uses mostly TCP as transport – optimized for small low-performance end-devices

• WAP 2.0 supports additionally:– Wireless Telephony Application (WTA), Push, and User Agent

Profile (UAPROF) utilize more advanced features in WAP 2.0 than in WAP1.x

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WAP-Improvements: WAP2.0 (3)

• Application development – easier development of WAP applications

– More comfortable user environment

• Migration aspects– WAP2.0 offers a migration to XHTML (Extensible Hypertext Markup

Language) and TCP (Transmission Control Protocol)

– Supporting XHTML, WAP 2.0 reduces development costs, allowing developers to write applications for both PC and WAP

• Security– offers more secure due to “end-to-end encryption” (from the mobile

device to the server)

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WAP2.0 and i-mode

• Competition & Fusion– NTT DoCoMo's I-Mode is a serious competitor

of WAP2.0– NTT DoCoMo's I-Mode moves in the direction

of support of XHTML and TCP, too– I-mode and WAP2.0 will probably converge

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Based partially on the materials of NTT-DoCoMo

i-Mode

An overview

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Structure

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Mobile Communication and Mobile Computing313

Overview• i-Mode is a product and a trademark of NTT-

DoCoMo• The enterprise NTT-DoCoMo started in February

1999 with a proprietary development: i-Mode, although NTT-DoCoMo is the member of WAP-Forum itself

• Meantime i-Mode has got a large number of registered users : over 33 millions

Source: http://www.nttdocomo.com

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Properties

• i-Mode is packet oriented– always online, no time delays to dial-up– billing regarding data volumes and not regarding to

time• simple page markup language – compact HTML

(cHTML)• End of 2002: change into XHTML (WAP 2.0)• a great success in Japan, because private computers

and private Internet access over fixed networks are infrequent

• In Germany E-plus has started i-Mode on 16th march 2002

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compact HTML• cHTML or compact HTML is a language subset

of HTML

• very simplified HTML

• Lists, Forms, Selections, Input fields are possible

• no Frames, no Tables, no CSS

• 166 additional pictograms, for instance

Fine

Motor sports WC

Heartbreak

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compact HTML (2)• Access key-Attribute for direct link activation respectively for direct

selection of input fields

• pictures can be displayed only in GIF-format, max. 5 KB per page. GIF-pictures mustn’t larger than 120*128 dots (little display)

• also animated GIFs

• 256 colours (capable of Display)

• Compact HTML Sites look like “normal” HTML, so also “normal” Browsers like Netscape can work with them

an i-Mode screenshot

i-Mode – on a mobile phone

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Network Configuration

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PDC:Personal Digital CellularTelecommunication System

PDC-P:PDC Packet System

BS:Base Station

IP:Information Provider

M-PGW: Mobile Message-Packet Gateway Module

MS:Mobile Station

M-SCP:Mobile-Service Control Point

NSP:Network Service Provider

PGW:Packet Gateway Module

PPM:Packet Processing Module

i-Mode network architecture

http://www.nttdocomo.co.jp/

IP

IP

i-mode Server

Connection Network

[NSP/Corporate LAN]

M-SCP PGW M-PGW

PPM PPM

BS

MS

BS

MS

BS

MS

BS

MS

Internet

PDC-PNetwork

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i-Mode network architecture (2)• i-Mode Server:

- consists of multiple server systems (B-,C-,M-Max ..), each server system is responsible for special tasks- represents the contents of „Information Providers“, operates Internet-Mail and i-Mode-Mail, enables the connection to Internet

• M-PGW (Mobile Message-Packet Gateway Module):transforms the protocols: TCP with i-Mode-Server and TLP (Transport Layer Protocol) with PPM

• PPM (Packet Processing Module):executes the packet connection with the mobile end-devices/peripherals

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i-Mode network architecture (3)• M-SCP (Mobile-Service Control Point):

authentication of user data (similar to voice communication)

• PGW (Packet Gateway Module):transition to other networks, for instance to offer the enterprises a Virtual Private Network (VPN)

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i-Mode protocol stack

RTCC MM

LAPDM

L1

TLP

AL (HTTP)

MS

CCRT MM

LAPDM

L1

PMAP

L2

L1

PPM

PMAP

L2

L1

PMAP

L2

L1

TCP/IP

L2

L1

TLP

UITP/NWMP

M-PGW

TCP/IP

L2

L1

UITP/NWMP

AL HTTP/SMTP

i-Mode ServerTLP:Transfer Layer ProtocolCC:Call ControlMM:Mobility ManagementRT:Radio Frequency Transmission ManagementLAPDM:Link Access Protocol on theD-Channel, modifiedPMAP:Packet Mobile Application Part

HTTP:HyperText Transport ProtocolSMTP:Simple Mail Transport Protocol UITP:User Information Transfer ProtocolNWMP:Network Management Protocol

TCP/IP: Transmission Control Protocol/Internet ProtocolL1:Layer1 (Physical Layer Protocol)L2:Layer2 (Data Link Layer Protocol)

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i-Mode protocol stack II• UITP (User Information Transfer Protocol):

transmits user information such as, for instance, MSN (Mobile Subscriber Number) to i-Mode-Server

• NWMP (Network Management Protocol):performs i-Mode Service-functions

• TLP (Transfer Layer Protocol): has a simplified transmission procedure and can transmit the signalization and user data together

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Java for mobile phones

• base: Java 2 micro edition and Java MIDP (Mobile Information Device Profile)

• downloading of Java-programs(ca. 30-50 kByte); color representation; applications, also games etc.

• billing via micro-payment of operator (ca. 1-5 € per application)

• products e.g. of Nokia, Ericsson, Siemens; support through big operators

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M-Commerce - applications

• Mobile Shopping

• Mobile Banking

• Mobile Brokerage

• Mobile Traveling

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Pervasive Computing

• Operation as parallel as possible of all users independent of the terminal, it means terminals with different equipment (PC‘s, mobile phones, PDAs, Applicances, etc.) should be supported by most different entrance nets

• It means finding a suitable system architecture for “multidimensional“ Internet communication (e.g. regarding end terminals) over *ML (Markup Languages)

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System architecture, one-dimensional

WWW-BrowserWeb Server

databases, etc.

Application Server

Thin Clients

Firewall Firewall

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Mobile Communication and Mobile Computing327

Browser-Client

ThinClient

Transaction-monitors

businessSoftware

Mainframe-applications

data bases

Out

er F

irew

all

Inne

r F

irew

all

Web-Server

HTML-Dokumente

HTML-DokumenteHTML-

Dokumente

HTML-DokumenteHTML-

documents

HTML-documents

HTML-Dokumente

HTML-DokumenteHTML-

Dokumente

HTML-DokumenteCGI-

scripts

CGI-scripts

Application-Server

proprietaryprotocols

proprietaryprotocols

proprietaryprotocols

HTTP

Stateless-connection

stateful-connection

Internet Inter-ORB ProtocolSOAP (Simple Object Access Protocol)

System architecture, one-dimensional

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Properties of application servers

main characteristics:• object-oriented communication systems• component- framework• transaction concepts• security concepts• connection of legacy applications• integration of WWW-services• general support of design, deployment and runtime

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System architecture, two- dimensional

WAP Server

WWW-BrowserWeb Server

Data bases, etc.

Application Server

Thin Clients

WAP-Browser

FirewallFirewall

…e.g.:BEA WebLogic M-Commerce Solution

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Application Server + WWW Server

XSL-Prozessors

System architecture, two- dimensional

Backend

standardize access to Backend, create business logic

call data from the EJBs and generate e.g. XML

convert XML into HTML, WML

Servlets EJBs

WAP-Server

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design principles

use in the Internet

more powerful than HTML

separation of content and style

possibility of definition of user-specific document-types

ability of XML-document processing

XML (Extensible Markup Language)

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specialtags

reference toStyle Sheet File

XML- document „bibliography“

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XML-Documents can have a DTD (Document Type Definition).The DTD can be contained in the document or can be referenced by a link.

A DTD specifies, which tags are permitted and how these can be combined.It has a special meaning for the processing of documents.

The processing programs can check XML- documents for structural errors with the help of DTD. If there is no error then a document is valid!

Well-formed documents contain no DTD- reference, but fulfill the XML-syntax-rules.

Valid and well-formed documents

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RULE for root-element

Cycle

Insert of lower elements

Accompanying Style Sheet File

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Mobile Communication and Mobile Computing335

Presentation in MS IE 5.0 correspondently IE6.0

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Mobile Communication and Mobile Computing336

Other Style Sheet File

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Mobile Communication and Mobile Computing337

Other presentation via XSL

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Mobile Communication and Mobile Computing338

XML

XSL

XSL-Processor EDI/WML

presentationfor processing

EDI:Electronic Document Interchange

Change of XML- documents

• Conversion of XML- documents into workable formats (with the help of XSL-Style-Sheets)

• e.g. into EDI- formats for commercial data processing

• in the mobile field very interesting for conversion into WML!

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Application Server + WWW Server

XSL-Processors

System architecture, multidimensional

Backend

call data from EJBs and generate e.g. XML

convert XML into *ML

Servlets EJBs

Access-Server

Standardize access to Backend, create business logic

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IBM Websphere Transcoding Publisher

• syntax customization of content• easy installation• little administration effort• changeable, expandable architecture of components

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IBM Websphere Transcoding Publisher

WAP – capable mobile phone

7.Output of contents

1.Request over port xx

Evaluation of used profiles

Text Clipper:transforms HTML into WML

Fragmentation Transcoder:Change into WML-decks

&

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Oracle Application Server Wireless Edition

• syntactic customization of content• renewable, expandable architecture of components• good customization of specific content

RequestManager

MasterService

Adapter

Trans-former

Request Manager authentifies user and calls Master Service

ClientRequest

the adapter fetches the Information

(via e.g. HTTP, SQL,

etc.)

Master Service configures und starts an

adapter

A transformer converts

information in suitable Client-

format

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Mobile Communication and Mobile Computing343

Oracle Application Server Wireless Edition

Expiry of a user request

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Mobile Communication and Mobile Computing344

Oracle Application Server Wireless Edition

Adapter and Transformer

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Mobile Communication and Mobile Computing345

Contents customization with XML / XSLT

• Separation of content and presentation• content client- independent in XML• XSLT: XSL transformations: a XML- data format is changed into a

new data format (not necessarily XML), this new data format can include platform dependent information about the presentation of data besides the main information

• presentation client- dependent in some XSLTs• XML-Support in many data bases • the server itself needs additional logic

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server-sided requests:• reconnaissance and classification of the client• choice of the suitable style sheets• parameter handover to XSLT• Processing of other documents (e.g. bitmaps)

Contents customization with XML / XSLT

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Example application: Pizza ordering service

• content and logic in same XML-document

• no presentation-semantic in XML, so all client- abilities can be used in XSLT

• but stylesheets are not reusable

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Example application: pizza ordering service

<?xml version='1.0' encoding="ISO-8859-1" standalone="no" ?><?xml-stylesheet type="text/xsl" href="Pizzaservices.xsl"?><?xml-stylesheet type="text/xsl" href="Pizzaservices.lynx.xsl" media="lynx"?><?xml-stylesheet type="text/xsl" href="Pizzaservices.lynx.xsl" media="palm"?><?xml-stylesheet type="text/xsl" href="Pizzaservices.wap.xsl" media="wap"?><?cocoon-process type="xsp"?><?cocoon-process type="xslt"?><xsp:page language="java" xmlns:xsp="http://www.apache.org/1999/XSP/Core"><xsp:logic>

class Item extends Vector {private int[] numbers;

public Item () {super ();numbers= new int[10];

}

public void setNumber (int nr, int a) {numbers[nr]=a;

}

public int getNumber (int nr) {return numbers[nr];

}}

...

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Mobile Communication and Mobile Computing349

<services> <service> <name>Hi Pizza</name> <banner>hellopizza.jpg</banner> <description>Hot Ware on Order</description> <location zipcode ="01277"> <address>Bodenbacher Strasse 16b, 01277 Dresden</address> <phone>03512540707</phone> <fax>03512540708</fax> </location > <location zipcode="01127"> <address>Mohnstraße 50, 01127 Dresden</address> <phone>03518485590</phone> <fax>03518485558</fax> </location > <proposal> <category name="Pizza"> <food> <name>Pizza Kentucky</name> <description>Salami</description> <price size="Normal">8.00</price> <price size="Jumbo">15.00</price> <price size="Pan">10.00</price> </food>...

Example application: pizza ordering service

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Pizza ordering service: PC-presentation

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Mobile Communication and Mobile Computing351

Pizza ordering service: presentation on Palmscape and in WAP

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XHTML

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Mobile Communication and Mobile Computing353

XHTML

• XHTML™ 1.0 is Extensible HyperText Markup Language (Second Edition)– reformulation of HTML 4 in XML 1.0– use instead of WML2.0 correspondently cHTML (i-

Mode)– basis for integration between WAP2.0 and i-Mode

WWW: http://www.w3.org/TR/xhtml1/#xhtml

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XHTML

• supporting via as well as WAP-Browsers also Netscape Navigator and Internet Explorer

• constituents:– DTD (Document Definition)– XSL (Extensible Stylesheet Language)

• large quantity of supported tags in comparison with WML2.0 and cHTML– CSS– frames– tables– forms/input fields– applet calls

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XHTML vs HTML

• XHTML describes data <-> HTML displays data! • XHTML – combining HTML and XML, and their

strengths• XHTML is oriented to internet/PC and mobile

internet/ mobile phones and hand helds• XHTML - compatibility

– everything has to be marked up correctly -> "well-formed" documents

– pages can be read by all XML enabled devices– upgrading of XML supported browsers– compatibility to all browsers– backward browser compatible

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Mobile agents

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Mobile Communication and Mobile Computing357

The agent- model

• an agent-system consists of the agents themselves and an execution engine for working with agents. The execution engine offers basic services to the agents

• Agent is an independent program generally, it consists of data, code and execution state, it works in interest and order of a third party (e.g. user, application).

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Hardware

OS

Hardware

Operating systemHardware

Operating System

Agent system

Network

place 4

Place 3

Place 1

place 5

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Mobile Communication and Mobile Computing359

Agent model

• migration: transfer of code, data, state• local interactions with server• transfer of the result

migrationClient

create Agentcode,data,

state

simpleServer-

interface

Clientresult Agent

code,data,

state

simpleServer-

interface

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Properties of mobile agents

Advantages: + reduction of network load

+ autonomy and asynchronity

+ dynamic adapting in environment

+ heterogeneity

+ robustness and error tolerance

+ scalability

+ personalization and individualization

+ dynamic code-installation

+ encapsulation of protocols

Disadvantages: – need of special execution

engine (Middleware)

– high security requirements

– transfer of code, data, state

– Decision: migration vs. remote communication

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Applications

• E-commerce• database requests• intelligent e-mails• Office applications/workflow• traffic telematic• Web surfing• load balancing • virtual enterprise• Mobile computing

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Mobile Communication and Mobile Computing362

Existing agent systems

• Voyager (ObjectSpace)• Aglets (IBM)• Concordia (Mitsubishi Electric)• Grasshopper (IKV++)• Odyssey (General Magic)

• Mole (Stuttgart), Ara (Kaiserslautern)• Agent TCL (Dartmouth University)• MASIF (OMG)• Telescript

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Mobile Communication and Mobile Computing363

Middleware for spontaneous Networking

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Mobile Communication and Mobile Computing364

Vision

JINI UPnP

• spontaneous networking of electrical devices (but not only computers)

• very simple connection• platform independence

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JAVA Intelligent Infrastructure, JINI

• „Middleware“ for spontaneous networking; originally developed from Sun

• JINI Connection Technology enables dynamic control of networked services and devices

• Partitioning into so called Lookup Groups: different sets of lookup-services

• basic operations:– Discovery: offers locating of a directory services (lookup

service)– Join: enables acquaintance/ registration of the services

implemented from some device

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JAVA Intelligent Infrastructure, JINI

• Lookup-Service enables locating of services via other users/devices per lookup-operations

• Leasing offers time-limited allocation of resources (using of services)

• Jini integrates distributed events processing and distributed transactions further on for co-ordination between services

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Mobile Communication and Mobile Computing367

Lookup service

JINI device / service

Client

Discovery & join

protocol Discovery lookup

General procedure: step 1

Page 368: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing368

Lookup Service

JINI device / service

Client

Proxy uploadProxy download

General procedure: step 2

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Mobile Communication and Mobile Computing369

JINI device / service

Client

Direct Connection

General procedure: step 3

• synchronization• data exchange between Device and Client

over own communication protocol

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JINI - Details

• Proxy hides all details of communication and is executed in the form of Client (dynamic installation of Stubs)

• security over RMI - Security Extension Framework• new versions of JINI Starter Kits include advanced possibilities, for

instance:– Caching of request results by Clients

– unicast-discovery

– comfortable control of using period (lease)

– asynchronous receiving of events among other features

• further development via JINI Community:– for instance JINI Surrogate Architecture: supports devices that do not

have all required resources for JAVA and JINI

– printer working group

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JINI - Assessment

• suitable to support scenarios from the field of Ubiquitous/Pervasive Computing

• JINI is a part of JAVA 2 Micro Edition

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Mobile Communication and Mobile Computing372

Universal Plug and Play, UPnP• reply of Microsoft to JINI• Embedded in UPnP- forum• with this improvement corresponding to Plug- and- Play

Standards, the PC peripheral devices should be connected to a home-network problem-less

• via Universal Plug and Play diverse devices can communicate with each other like with Jini

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Universal Plug and Play, UPnP

• essentially based on open standards like TCP/IP and therefore is compatible to each network

• in Windows ME integrated• a special toolkit for creation of drivers on the basis of

UPnP developed by INTEL

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Mobile Communication and Mobile Computing374

Home application

Universal PnP

Bus attached

(ISA,PCI,USB,

IEEE,1394,IR,..)

Discovery Description Usage

Internet Protocol attached

Network media(Ethernet,HomeRF,

HomePNA,..

IrDA X10

IR PLC

..

..

Common Abstrac-

tions

Common Interfaces

Media Indepen-

dence

UPnP architecture

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Mobile Communication and Mobile Computing375

Further approaches

HAVi – Home Audio and Video Interop.• essentially supported by the vendors of consumer-electronics field• UPnP Forum is interlocked however represented more broadly on

the market (specially also in computer-industry)

HomePlug• consortium for standardizing of data communication over (low

voltage) power cable• performance like by IEEE 802.11b

• the members are among others Cisco and Panasonic

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Mobile Communication and Mobile Computing376

Services and system support for Mobile Computing

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Mobile Communication and Mobile Computing377

Mobile Computing: system support

Essential properties und requirements:

• dynamics, localization

• heterogeneity of networks and end-devices

• security problems

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Mobile Communication and Mobile Computing378

Product Data

Main officeCaching

ClientLAN-Access

Maintenance technician

- very different performance and charges: GSM, ISDN, LAN

Software-technical, automatic adaptation to concrete system environmentExample: Access to picture data/compressed picture

data/graphics/text

Mobile Access

Local Resources,Error Protocols

Mobile distributed applications: example

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Mobile Communication and Mobile Computing379

Problems and requirements

Problem fields:

• dynamic system and net configuration

• dynamic change of Quality-of-Service-properties

• uncoupling/re-connection

• transparency of resource access

• security aspectsRequirements:

• connection monitoring and selection

• treatment of uncoupling/off-sets and migration; emulation of services

• configuration update

• localization of mobile servers and clients

• advanced security and transaction services

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Mobile RPC

Goals:• Mobile Binding

– Transparent call to an alternative server by non-accessibility

• Datagram RPC– Queuing of calls in disconnected status

• Queued RPC– intermediate storage and delivery of results after re-coupling

Realization:• Attachment on existent RPC- systems (without new implementation

or internal code changes)

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Decoupling

Net connection

RPC reaches Server

Return to Client

Time Behavior Datagram RPC

T1 T2 Time T3 T4

•Client

•Server

•DCE RPC

•Datagram RPC

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Mobile Communication and Mobile Computing382

Message Queuing: MQ Series example

• Base: Messages, Queues with Queue Manager• dynamic coupling between applications and local Queues via

logon/logoff • using of Queues for transmission or receiving; also mixed using is

possible• coupling of distributed Queue Managers via Message Channels• Internet Gateway, C++- and Java-Support• support of essential operating system platforms

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Mobile Communication and Mobile Computing383

Example scenario

• decoupling of application through Queue Manager:– Message forwarding is possible even if application

isn’t running

Computer A

Queue Manager

Queue Manager

App-lication

1 MQPUT

MQGET

Computer B

Queue Manager

Queue Manager

App-lication

2MQGET

MQPUT

MessageChannel

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Mobile Communication and Mobile Computing384

N:M - communication

A

B

C

D

EQueue, with

optional support of message priorities

Access to Servervia multiple Clients

• Load balancing (selective delivery) or

• Parallel processing (replicated delivery)

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Message Queuing: Assessment

Advantages+ simple manageability+ robust message delivery + flexible application fields (for instance load balancing,

parallelization, batch-transmission of branch data etc.)+ relevant for easy coupling of programs, for instance via Internet,

or for Mobile Computing

Disadvantages− limited communication semantics− interaction model is different than with procedures/method

invocations− limited accessibility of higher services− only several proprietary decisions up to now, only step-by-step

standardization

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Ethernet

Ethernet

Ethernet

E-Fax-OrderE-Fax-Order

ManagementDB-Access

ManagementDB-Access

FirmBranch office

Client X

GSM

xDSL

Application

Resource

Mobile Station

Communication path

DBDistributed Database

Distributed Database

Cache

Application Structure

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Mobile Communication and Mobile Computing387

Domain-concept

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Mobile Communication and Mobile Computing388

Main functionality: Domain and Station Manager

Domain Manager:• management of all global objects (users, global

available resources, stations, net topology)

Station Manager:• management of all local objects of a station (net

access, running applications etc.)

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Architecture of Station Manager

Authentication and Encryption Service

Application

Subsystem(Application Programming Interface)

Subsystem

(System Calls)

Location Service

Application Data Mobilizer and Manager

Registry Service

Bandwidth and CostManagement Service

Disconnected Operation Handling Service (CS, QS, CHS, BMC)

Active Database

Resource Broker

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Mobile Multimedia Email: message transfer

User Agent

Message Store

Email Proxy

Queuing Service

Subsystem

Queuing Service

message transferMobile Enhanced Message Handling

System

em

ail

pro

toc

ol

email protocol

email protocol

Page 391: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing391

Mobile Multimedia Email: selection of quality parameters

Cent Cent

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Mobile Communication and Mobile Computing392

Mobile File Manager: example CODA

• distributed file system, which offers the unbreakable access to data also in the case of server shut-down or net failure

• developed at the Carnegie Mellon University• based on AFS (Andrew File System, distributed

file system in UNIX-environment)• relatively transparent to the applications

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CODA overview

• based on the model of „Disconnected Operations”• client keeps Read- and Write-access on the data via

inset of a local buffer (Cache) also during temporary disconnection from net

• with re-connection system forwards changes and recognizes potential conflicts

• for different operating systems available (for instance LINUX, Solaris, Windows)

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CODA system model

Replicated Server:High availability

Net communicationat file open and close

Client(“Whole-File-Caching”)

Disconnected Client:local data accesson Cache

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Mobile Communication and Mobile Computing395

properties of consistence (Coda)

• Callback– logic reference from server to the active client, used for

immediate information about file changes via other client

• after connection failures the file in client cache remains valid till to timeout termination (as a rule several minutes)

• thereby reduced consistency• conflict processing explicitly in interactive form, however

low conflict probability

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Conflict processing (CODA)

• extensive automation as objective purpose, however isn’t possibly for:– Update/Update-conflict: independent double update of the same

file– Delete/Update-conflict: independent erasure respectively update

of the same file– Name/Name-conflict: generating of two files with the same name

Manual access after user notification

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Cache management (Coda)

• “Cache-Misses”: searched file isn’t in the Client-Cache– processing failure in the disconnected status

• priority list of important files per user– the highest priority is always kept in the cache (for instance

by system programs, user profiles, address files etc.)– other priorities: exchange strategies correspondent to

importance– dynamic generated files via list of essential operations

referenced (for instance actual test protocol etc.)

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File synchronization under Windows

- Windows: over System Control -> Management -> Services so called „file replication (server)“ for synchronization of data between different servers

- under Explorer -> Extras -> Synchronization: - Synchronization of own Homepage with PC - Synchronization of Sites in WWW

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Mobile Communication and Mobile Computing399

E-Hand

http://www.ehand.com/ehand/

- connects existing Enterprise Systems with mobile end-devices

- platform independent- very simple synchronization and data transfer- supports XML, ODBC and SyncML

Advantages:

- contains Web-similar user interface for application installation and for mobile participants

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E- Hand

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Mobile Communication and Mobile Computing401

Motivation:

• SFA-Sales-force-automation:

-> actual information about clients, competitors and market trends to the field (outside-) workers

• emergent business transactions on the site -> efficiency increasing

Example:

Pharmaceutical Industry

• visit of 6 up to 8 distribution medics per day

• to bring dialogue to the point more quickly– previous information about the medic (contacts, receipt prescription habits)

are recallable from the firm-net

• presently still manually due to dialogue recording and product documentation

• in the future via mobile databases permanently faster access to data without inconvenient storage, connection establishment etc.

Mobile databases support

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Mobile Communication and Mobile Computing402

• mobile databases offer principally data synchronization and replication of enterprise servers and for mobile end-devices like PALM etc.

• due to increasingly mobile business processes there is a necessity of databases, which must perform these functionalities among other things:– quickly– compatible to as many as possible mobile systems

• 2 mobile database types:– “asynchronous synchronization”: for instance SQL Remote of Sybase

• data replication between central database and multiple remote databases• also offline-working is possible due to email-queuing principle (sent, if connected)

– “synchronous synchronization”: for instance Sybase Mobilink Synchronization Server

• co-operation with databases of other vendors (via Server Middleware)• permanent connection necessary, for instance via GSM

Mobile databases support

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Mobile Communication and Mobile Computing403

IBM DB2 Everyplace

• compatible for instance to Windows CE, PalmOS, EPOC ...• footprint: ~150 k (storage requirements)• for data balancing DB Everyplace Sync Server is necessary

– synchronization with other Handhelds without PC!

• includes so called Mobile Devices Administration Center enables central management of all mobile end-devices of a enterprise

• supports integration of enterprise data from different databases and other sources (DB2 replication technology, JDBC, Adapter API for customized decisions)

• data are encrypted during synchronization (56 or 128 Bit)• supports automatic conflict processing

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Mobile Communication and Mobile Computing404

IBM DB2 Everyplace

Source: http.//www.ibm.com

SynchronizationServer

Backend

IBM DB2Microsoft

OracleInformixSybase

Other DBMS (JDBC)

Mobile Devices

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Mobile Communication and Mobile Computing405

Oracle Lite

• 3 constituents:– Oracle Lite DBMS

• database with low footprint (storage requirements)• Java-enabled

– iConnect• components for synchronization and creation of messaging-

applications (principle of message queues)

– Web-to-go• components supporting development, deployment and

management of mobile Web-applications

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Mobile Communication and Mobile Computing406

Oracle Lite

replication via Internet

File-based replication

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Mobile Communication and Mobile Computing407

Sybase SQL Anywhere Studio

• mini-database, can be operated on the PDAs• supports PalmOS, EPOC and WindowsCE• small „footprint“: ~50kByte• developer can adapt the database according to the required SQL-

properties, modular design principle• synchronization enables data balancing with the enterprises

database, all well-known database vendors are supported• only the changed data are transmitted• both local (for instance B. Hotsync (Palm)) and remote

synchronization supported• architecture similar to IBM DB2 Mobile Connect

(Source: http://www.sybase.com/products/anywhere/)

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Mobile Communication and Mobile Computing408

Further approaches

• Microsoft Mobile Information Server

• Lotus Everyplace

• numerous further products, mostly similar architecture concepts

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Mobile Communication and Mobile Computing409

Further sample applications

• Traffic management• Mobile Information Services• M-Commerce

• Service technician• Customer consultant• Field workers in general• Environmental engineering (measurement data logging)• Medic (visits on site)

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Mobile Communication and Mobile Computing410

Traffic management

Services:• Traffic engineering• Travel information• Maintenance service • Mobile Office

Paris

Berlin

Dresden

Service Center

“Local” Provider

“Global” Provider

Page 411: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing411

GPSGSM

Internet

PSTN/ISDN

End-user Distributed Service-Center

Distributed Information services

VirtualPrivate

Network

Center A

Center B

Information Provider

Info

InfoInfo

InfoInfo

Info

Traffic management

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Mobile Communication and Mobile Computing412

PrinterHost

Notepad HUB PC Terminal

Application scenario: car maintenance

Page 413: Mobile Communication and Mobile Computing

Mobile Communication and Mobile Computing413

Client

Client (mobile)low battery resource

Server for instance WWW

low band width

Online-information services

• Client/Server-access by individual requests• additionally: separate broadcast-channel from Server to the mobile

Clients: transmission and caching of frequently requested information; thereby lower battery consumption (receiving less expensive as sending for the Client)

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Optimization: basic concept

• information in Publication-Group: regular Broadcast

• information in On-Demand-Group: Client/Server-queries

• exchange between both groups on the basis of:– access frequency (for instance on WWW-pages)– page modification frequency– channel bandwidths– clients storage volumes (Cache)

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Mobile e-Mail

Quelle: http://www.eudora.com

• Eudora Internet Suite, consists of:– Eudora email for the Palm computing platform– EudoraWeb browser for the Palm Computing platform– Eudora Mail Conduit

• Properties:– Eudora and EudoraWeb browser support SSL (Secure Sockets

Layer) and TLS (Transport Layer Security), i.e. end-to-end security

– synchronization of bookmarks between PC Web-Browser and EudoraWeb browser via Eudora Web Conduit

– synchronization with PC-Email applications– several Email-accounts

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Alternative M-Commerce applications

• 12snap.de (pronounciation: “one two snap”)– Auctioning channel

• www.paybox.de– Cashless payments

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Mobile Communication and Mobile Computing417

Sample: 12snap system architecture

mobile radionet D2

center

Offers viaCellularBroadcast

externalprovider

Internet

Call Center

Automatic processing of the orders whichare incoming viaphone-service; also coupling of WAP and telephony

Users are registered by 12snap and enable direct debit, respectively booking via the credit card;Orders are sent to a Call-Center via keyboard tone, clientidentification takes place via his phone number(CLIP = Calling Line Identification Presentation)

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Sample: paybox.net

• Client is registered in the Internet by paybox.net and enables direct debit

• Client obtains as a result so called Paybox-PINs; using Paybox-PIN client can unblock the transactions

• purchase payments in the Internet are carried out as follows:– Client selects „Paybox“ as a payment type– Merchant sends transaction to Paybox-provider via secure data

connection – Provider dials up the clients via phone numbers stored in his

master data– then Client can unblock the transaction with his PIN– Paybox transfers money via direct debit and forwards it to the

Merchant