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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 1 GSM and UMTS Market GSM Overview Services Sub-systems Components UMTS/IMT-2000 Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 2 Mobile phone subscribers worldwide year Subscribers [million] 0 200 400 600 800 1000 1200 1400 1600 1996 1997 1998 1999 2000 2001 2002 2003 2004 approx. 1.7 bn GSM total TDMA total CDMA total PDC total Analogue total W-CDMA Total wireless Prediction (1998) Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 3 Development of mobile telecommunication systems 1G 2G 3G 2.5G IS-95 cdmaOne IS-136 TDMA D-AMPS GSM PDC GPRS IMT-DS UTRA FDD / W-CDMA EDGE IMT-TC UTRA TDD / TD-CDMA cdma2000 1X 1X EV-DV (3X) AMPS NMT IMT-SC IS-136HS UWC-136 IMT-TC TD-SCDMA CT0/1 CT2 IMT-FT DECT CDMA TDMA FDMA IMT-MC cdma2000 1X EV-DO HSDPA Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 4 How does it work? How can the system locate a user? Why don’t all phones ring at the same time? What happens if two users talk simultaneously? Why don’t I get the bill from my neighbor? Why can an Australian use her phone in Berlin? Why can’t I simply overhear the neighbor’s communication? How secure is the mobile phone system? What are the key components of the mobile phone network?

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Page 1: GSM and UMTS - University of Hong Kongkcleung/courses/csis7304/Summer.2006/... · GSM and UMTS Market GSM Overview Services Sub-systems Components UMTS/IMT-2000 ... Architecture of

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 1

GSM and UMTS

MarketGSM

OverviewServicesSub-systemsComponents

UMTS/IMT-2000

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 2

Mobile phone subscribers worldwide

year

Subs

crib

ers

[mill

ion]

0

200

400

600

800

1000

1200

1400

1600

1996 1997 1998 1999 2000 2001 2002 2003 2004

approx. 1.7 bn

GSM total

TDMA total

CDMA total

PDC total

Analogue total

W-CDMA

Total wireless

Prediction (1998)

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 3

Development of mobile telecommunication systems

1G 2G 3G2.5G

IS-95cdmaOne

IS-136TDMAD-AMPSGSMPDC

GPRS

IMT-DSUTRA FDD / W-CDMA

EDGE

IMT-TCUTRA TDD / TD-CDMA

cdma2000 1X

1X EV-DV(3X)

AMPSNMT

IMT-SCIS-136HSUWC-136

IMT-TCTD-SCDMA

CT0/1

CT2IMT-FTDECT

CD

MA

TDM

AFD

MA

IMT-MCcdma2000 1X EV-DO

HSDPA

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 4

How does it work?

How can the system locate a user?Why don’t all phones ring at the same time?What happens if two users talk simultaneously?Why don’t I get the bill from my neighbor?Why can an Australian use her phone in Berlin?

Why can’t I simply overhear the neighbor’s communication?How secure is the mobile phone system?What are the key components of the mobile phone network?

Page 2: GSM and UMTS - University of Hong Kongkcleung/courses/csis7304/Summer.2006/... · GSM and UMTS Market GSM Overview Services Sub-systems Components UMTS/IMT-2000 ... Architecture of

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 5

GSM: Overview

GSMformerly: Groupe Spéciale Mobile (founded 1982)now: Global System for Mobile CommunicationPan-European standard (ETSI, European Telecommunications Standardisation Institute)simultaneous introduction of essential services in three phases (1991, 1994, 1996) by the European telecommunication administrations (Germany: D1 and D2)

seamless roaming within Europe possibletoday many providers all over the world use GSM (more than 200 countries in Asia, Africa, Europe, Australia, America)more than 1.2 billion subscribers in more than 630 networksmore than 75% of all digital mobile phones use GSM (74% total)over 200 million SMS per month in Germany, > 550 billion/year worldwide(> 10% of the revenues for many operators)[be aware: these are only rough numbers…]

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 6

Performance characteristics of GSM (wrt. analog sys.)

Communication mobile, wireless communication; support for voice and data services

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

Worldwide connectivityone number, the network handles localization

High capacity better frequency efficiency, smaller cells, more customers per cell

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

Security functions access control, authentication via chip-card and PIN

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 7

Disadvantages of GSM

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

B-channel (bearer channel): channel that carries main data

reduced concentration while drivingelectromagnetic radiation

abuse of private data possibleroaming profiles accessible

high complexity of the systemseveral incompatibilities within the GSM standards

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 8

GSM: Mobile Services

GSM offersseveral types of connections

voice connections, data connections, short message servicemulti-service options (combination of basic services)

Three service domainsBearer ServicesTelematic ServicesSupplementary Services

Enhancements for standard telephony service

GSM-PLMNtransit

network(PSTN, ISDN)

source/destination

networkTE TE

bearer services

tele services

R, S (U, S, R)Um

MT

MS

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 9

Bearer Services

Telecommunication services to transfer data between access pointsSpecification of services up to the terminal interface (OSI layers 1-3) Different data rates for voice and data (original standard)

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

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

transparent bearer servicesdo not try to recover lost data

non-transparent bearer servicesuse protocols of layers 2 and 3 to implement error correction and flow control

Today: data rates of approx. 50 kbit/s possible – will be covered later!

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 10

Tele Services I

Telecommunication services that enable voice communication via mobile phonesAll these basic services have to obey cellular functions, security measurements etc.

encrypted voice transmission, message services, and basic data communication with terminals as known from the PSTN or ISDN

Offered servicesmobile telephonyprimary goal of GSM was to enable mobile telephony offering the traditional bandwidth of 3.1 kHz Emergency numbercommon number throughout Europe (112); mandatory for all service providers; free of charge; connection with the highest priority (preemption of other connections possible)Multinumberingseveral ISDN phone numbers per user possible

according to the desired service

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 11

Tele Services II

Additional servicesNon-Voice-Teleservices

group 3 faxvoice mailbox (implemented in the fixed network supporting the mobile terminals)electronic mail (MHS, Message Handling System, implemented in the fixed network)...

Short Message Service (SMS)alphanumeric data transmission to/from the mobile terminal (160 characters) using the signaling channel, thus allowing simultaneous use of basic services and SMS(almost ignored in the beginning now the most successful add-on!)

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 12

Supplementary services

Services in addition to the basic services, cannot be offered stand-aloneSimilar to ISDN services besides lower bandwidth due to the radio linkMay differ between different service providers, countries and protocol versions Important services

identification: forwarding of caller numbersuppression of number forwardingautomatic call-back: keep trying the number until getting throughconferencing with up to 7 participantslocking of the mobile terminal (incoming or outgoing calls)...

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 13

Architecture of the GSM system (GSM-PLMN)

GSM is a PLMN (Public Land Mobile Network)several providers setup mobile networks following the GSM standard within each countrycomponents

MS (mobile station)BS (base station)MSC (mobile switching center)LR (location register)

subsystemsRSS (radio subsystem): covers all radio aspectsNSS (network and switching subsystem): call forwarding, handover, switchingOSS (operation subsystem): management of the network

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 14

Ingredients 1: Mobile Phones, PDAs & Co.

The visible but smallestpart of the network!

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 15

Ingredients 2: Antennas

Still visible – cause many discussions…

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 16

Ingredients 3: Infrastructure 1

Base Stations

Cabling

Microwave links

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 17

Ingredients 3: Infrastructure 2

Switching units

Data bases

Management

Monitoring

Not „visible“, butcomprise the major partof the network (also from an investmentpoint of view…)

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 18

GSM: overview

fixed network

BSC

BSC

MSC MSC

GMSC

OMC, EIR, AUC

VLR

HLRNSSwith OSS

RSS

VLR

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 19

GSM: elements and interfaces

NSS

MS MS

BTS

BSC

GMSC

IWF

OMC

BTS

BSC

MSC MSC

Abis

Um

EIR

HLR

VLR VLR

A

BSS

PDN

ISDN, PSTN

RSS

radio cell

radio cell

MS

AUCOSS

signaling

O

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 20

Um

Abis

ABSS

radiosubsystem

MS MS

BTSBSC

BTS

BTSBSC

BTS

network and switching subsystem

MSC

MSC

fixedpartner networks

IWF

ISDNPSTN

PSPDNCSPDN

SS

7

EIR

HLR

VLR

ISDNPSTN

GSM: system architecture

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 21

System architecture: radio subsystem

ComponentsMS (Mobile Station)BSS (Base Station Subsystem):consisting of

BTS (Base Transceiver Station):sender and receiverBSC (Base Station Controller):controlling several transceivers

InterfacesUm : radio interfaceAbis : standardized, open interface with 16/64 kbit/s user channelsA: standardized, open interface with 64 kbit/s user channels

Um

Abis

A

BSS

radiosubsystem

network and switchingsubsystem

MS MS

BTSBSC MSC

BTS

BTSBSC

BTSMSC

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 22

System architecture: network and switching subsystem

ComponentsMSC (Mobile Services Switching Center):IWF (Interworking Functions)

ISDN (Integrated Services Digital Network)PSTN (Public Switched Telephone Network)PSPDN (Packet Switched Public Data Net.)CSPDN (Circuit Switched Public Data Net.)

DatabasesHLR (Home Location Register)VLR (Visitor Location Register)EIR (Equipment Identity Register)

networksubsystem

MSC

MSC

fixed partnernetworks

IWF

ISDNPSTN

PSPDNCSPDN

SS

7

EIR

HLR

VLR

ISDNPSTN

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 23

Radio subsystem

The Radio Subsystem (RSS) comprises the cellular mobile network up to the switching centersComponents

Base Station Subsystem (BSS):Base Transceiver Station (BTS): radio components including sender, receiver, antenna - if directed antennas are used one BTS can cover several cellsBase Station Controller (BSC): switching between BTSs, controlling BTSs, managing of network resources, mapping of radio channels (Um) onto terrestrial channels (A interface)

BSS = BSC + sum(BTS) + interconnection

Mobile Stations (MS)

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 24

possible radio coverage of the cell

idealized shape of the cellcell

segmentation of the area into cells

GSM: cellular network

use of several carrier frequenciesnot the same frequency in adjoining cellscell sizes vary from some 100 m up to 35 km depending on user density, geography, transceiver power etc.hexagonal shape of cells is idealized (cells overlap, shapes depend on geography)if a mobile user changes cells

handover of the connection to the neighbor cell

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 25

GSM frequency bands

921-960921-925

876-915876-880

955-1024, 0-12469 channels

GSM-Rexclusive

1930-19901850-1910512-810GSM 1900 (Americas)

1805-18801710-1785512-885GSM 1800

921-960935-960925-960

876-915890-915880-915

0-124, 955-1023124 channels+49 channels

GSM 900classicalextended

869-894824-849128-251GSM 850 (Americas)

Downlink [MHz]Uplink [MHz]ChannelsType

- Additionally: GSM 400 (also named GSM 450 or GSM 480 at 450-458/460-468 or 479-486/489-496 MHz- Please note: frequency ranges may vary depending on the country!- Channels at the lower/upper edge of a frequency band are typically not used

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 26

Example coverage of GSM networks (www.gsmworld.com)

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

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

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 27

Base Transceiver Station and Base Station Controller

Tasks of a BSS are distributed over BSC and BTSBTS comprises radio specific functionsBSC is the switching center for radio channels

Functions BTS BSCManagement of radio channels XFrequency hopping (FH) X XManagement of terrestrial channels XMapping of terrestrial onto radio channels XChannel coding and decoding XRate adaptation XEncryption and decryption X XPaging X XUplink signal measurements XTraffic measurement XAuthentication XLocation registry, location update XHandover management X

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 28

Mobile station

Terminal for the use of GSM servicesA mobile station (MS) comprises several functional groups

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

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

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

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

R S UmTE TA MT

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 29

Network and switching subsystem

NSS is the main component of the public mobile network GSMswitching, mobility management, interconnection to other networks, system control

mobility management: handovers between different BSSs

ComponentsMobile Services Switching Center (MSC)controls all connections via a separated network to/from a mobile terminal within the domain of the MSC - several BSC can belong to a MSCDatabases (important: scalability, high capacity, low delay)

Home Location Register (HLR)central master database containing user data, permanent and semi-permanent (dynamic) data of all subscribers assigned to the HLR (one provider can have several HLRs)Visitor Location Register (VLR)local database for a subset of user data, including data about all user currently in the domain of the VLR

– avoid frequent HLR updates and long-distance signalling of user information

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 30

Mobile Services Switching Center

The MSC (mobile switching center) plays a central role in GSMswitching functionsadditional functions for mobility supportmanagement of network resourcesinterworking functions via Gateway MSC (GMSC)integration of several databases

Functions of a MSCspecific functions for paging and call forwardingtermination of SS7 (signaling system no. 7)

SS7: handles all signalling needed for connection setup, connection release and handover of connections to other MSCs

mobility specific signalinglocation registration and forwarding of location informationprovision of new services (fax, data calls)support of short message service (SMS)generation and forwarding of accounting and billing information

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 31

Operation subsystem

The OSS (Operation Subsystem) enables network operation, management, and maintenance of all GSM subsystemsComponents

Authentication Center (AUC)situated in a special protected part of the HLR generates user specific authentication parameters on request of a VLR authentication parameters used for authentication of mobile terminals and encryption of user data on the air interface within the GSM system

Equipment Identity Register (EIR)registers GSM mobile stations and user rightsstolen or malfunctioning mobile stations can be locked and sometimes even localized

Operation and Maintenance Center (OMC)different control capabilities for the radio subsystem and the network subsystemtraffic monitoring, status reports of network entities, subscriber and security management, or accounting and billing

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 32

1 2 3 4 5 6 7 8

higher GSM frame structures

935-960 MHz124 channels (200 kHz)downlink

890-915 MHz124 channels (200 kHz)uplink

frequ

ency

time

GSM TDMA frame

GSM time-slot (normal burst)

4.615 ms

546.5 µs577 µs

tail user data TrainingSguardspace S user data tail

guardspace

3 bits 57 bits 26 bits 57 bits1 1 3

GSM - TDMA/FDMA

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 33

GSM – TDMA/FDMA (Definitions)

Normal burstdata transmission

Tailset to 0used to enhance the receiver performance

Training sequenceadapt the parameters of the receiver to the current path propagation characteristicsselect the strongest signal in case of multi-path propagation

Flag Sindicate whether the data field contains user or network control data

Guard spaceavoid overlapping with other bursts due to different path delaysgive the transmitter time to turn on and off

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 34

GSM hierarchy of frames

0 1 2 2045 2046 2047...hyperframe: count each TDMA frame as input for encryption algorithm

0 1 2 48 49 50...

0 1 24 25...

superframe

0 1 24 25...

0 1 2 48 49 50...

0 1 6 7...

multiframe

frame

burstslot

577 µs

4.615 ms

120 ms (traffic)

235.4 ms (control)

6.12 s

3 h 28 min 53.76 s

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 35

GSM protocol layers for signaling

CM

MM

RR

MM

LAPDm

radio

LAPDm

radio

LAPD

PCM

RR’ BTSM

CM

LAPD

PCM

RR’BTSM

16/64 kbit/s

Um Abis A

SS7

PCM

SS7

PCM

64 kbit/s /2.048 Mbit/s

MS BTS BSC MSC

BSSAP BSSAP

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 36

GSM protocol layers for signaling (Definitions)

Layer 1handles all radio-specific functions

LAPDmoffers reliable data transfer over connectionsre-sequencing of data framesflow control

LAPD: LAPDm + synchronization and checksumming for error detectionRadio resource management (RR)

setup, maintenance, and release of radio channelsMobility management (MM)

functions for registration, authentication, identification, location updating, and the provision of a temporary mobile subscriber identity (TMSI)

Call management (CM)call control, short message service, and supplementary service

Pulse code modulation (PCM)offer transparent 64 kbps digital channels

BTS management (BTSM)functions of RR’ supported by BSC via BTS

BSS application part (BSSAP)controls a BSS by MSC

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 37

Mobile Terminated Call

PSTNcallingstation GMSC

HLR VLR

BSSBSSBSS

MSC

MS

1 2

3

45

6

7

8 9

10

11 12

1316

10 10

11 11 11

14 15

17

1: calling a GSM subscriber2: forwarding call to GMSC3: signal call setup to HLR4, 5: request MSRN from VLR6: forward responsible

MSC to GMSC7: forward call to

current MSC8, 9: get current (availability) status of MS10, 11: paging of MS12, 13: MS answers14, 15: security checks16, 17: set up connection

MSRN: mobile station roaming number

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 38

Mobile Originated Call

PSTN GMSC

VLR

BSS

MSC

MS1

2

6 53 4

9

10

7 8

1, 2: connection request3, 4: security check5-8: check resources (free circuit)9-10: set up call

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 39

MTC/MOC

BTSMS

paging request

channel request

immediate assignment

paging response

authentication request

authentication response

ciphering command

ciphering complete

setup

call confirmed

assignment command

assignment complete

alerting

connect

connect acknowledge

data/speech exchange

BTSMS

channel request

immediate assignment

service request

authentication request

authentication response

ciphering command

ciphering complete

setup

call confirmed

assignment command

assignment complete

alerting

connect

connect acknowledge

data/speech exchange

MTC MOC

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 40

4 types of handover

MSC MSC

BSC BSCBSC

BTS BTS BTSBTS

MS MS MS MS

12 3 4

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 41

GSM Handover

Intra-cell handoverchange the carrier frequency

Inter-cell, intra-BSC handoverassign a new radio channel in the new cell and release the old one

Inter-BSC, intra-MSC handoverperform handovers between cells controlled by different BSCs

Inter-MSC handoverhandover between two cells belonging to different MSCs

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 42

Handover decision

receive levelBTSold

receive levelBTSold

MS MS

HO_MARGIN

BTSold BTSnew

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 43

Handover procedure

HO access

BTSold BSCnew

measurementresult

BSCold

Link establishment

MSCMSmeasurementreport

HO decisionHO required

BTSnew

HO request

resource allocationch. activation

ch. activation ackHO request ackHO commandHO commandHO command

HO completeHO completeclear commandclear command

clear complete clear complete

HO complete

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 44

Security in GSM

Security servicesaccess control/authentication

user SIM (Subscriber Identity Module): secret PIN (personal identification number)SIM network: challenge response method

– challenge: random number; response: signed response (SRES)

confidentialityvoice and signaling encrypted on the wireless link (after successful authentication)

anonymitytemporary identity TMSI (Temporary Mobile Subscriber Identity)newly assigned at each new location update (LUP)encrypted transmission

3 algorithms specified in GSMA3 for authentication (“secret”, open interface)A5 for encryption (standardized)A8 for key generation (“secret”, open interface)A3 and A8: proprietary

“secret”:• A3 and A8 available via the Internet• network providers can use stronger mechanisms

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 45

GSM - authentication

A3

RANDKi

128 bit 128 bit

SRES* 32 bit

A3

RAND Ki

128 bit 128 bit

SRES 32 bit

SRES* =? SRES SRES

RAND

SRES32 bit

mobile network SIM

AC

MSC

SIM

Ki: individual subscriber authentication key SRES: signed response

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 46

GSM - key generation and encryption

A8

RANDKi

128 bit 128 bit

Kc64 bit

A8

RAND Ki

128 bit 128 bit

SRES

RAND

encrypteddata

mobile network (BTS) MS with SIM

AC

BSS(BTS / BSC)

SIM

A5

Kc64 bit

A5MS

data data

cipherkey

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 47

Data services in GSM I

Data transmission standardized with only 9.6 kbit/sadvanced coding allows 14,4 kbit/snot enough for Internet and multimedia applications

HSCSD (High-Speed Circuit Switched Data)mainly software update (upgrades in MS and MSC)bundling of several time-slots to get higher AIUR (Air Interface User Rate)(e.g., 57.6 kbit/s using 4 slots, 14.4 each)advantage: ready to use, constant quality, simpledisadvantage: channels blocked for voice transmission

still use the connection-oriented mechanisms of GSMAIUR [kbit/s] TCH/F4.8 TCH/F9.6 TCH/F14.4

4.8 19.6 2 1

14.4 3 119.2 4 228.8 3 238.4 443.2 357.6 4

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 48

Data services in GSM II

GPRS (General Packet Radio Service)packet switchingusing free slots only if data packets ready to send (e.g., 50 kbit/s using 4 slots temporarily)standardization 1998, introduction 2001advantage: one step towards UMTS, more flexibledisadvantage: more investment needed (new hardware)

GPRS network elementsGSN (GPRS Support Nodes): GGSN and SGSNGGSN (Gateway GSN)

interworking unit between GPRS and PDN (Packet Data Network)SGSN (Serving GSN)

supports the MS (location, billing, security)GR (GPRS Register)

user addressesmapping between a mobile’s identity and the PSPDN address

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 49

GPRS quality of service

Reliabilityclass

Lost SDUprobability

DuplicateSDU

probability

Out ofsequence

SDUprobability

Corrupt SDUprobability

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

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

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

Delay SDU size 128 byte SDU size 1024 byteclass mean 95 percentile mean 95 percentile

1 < 0.5 s < 1.5 s < 2 s < 7 s2 < 5 s < 25 s < 15 s < 75 s3 < 50 s < 250 s < 75 s < 375 s4 unspecified

Delay-- channel access delay, coding for error correction, and transfer delay

in the fixed and wireless part of the GPRS network

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 50

Examples for GPRS device classes

54412

52410

5148

4225

3223

3122

2111

Maximum number of slotsSending slotsReceiving slotsClass

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 51

GPRS user data rates in kbit/s

171.2149.8128.410785.664.242.821.4CS-4

124.8109.293.67862.446.831.215.6CS-3

107.293.880.46753.640.226.813.4CS-2

72.463.3554.345.2536.227.1518.19.05CS-1

8 slots7 slots6 slots5 slots4 slots3 slots2 slots1 slotCoding scheme

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 52

GPRS architecture and interfaces

MS BSS GGSNSGSN

MSC

Um

EIR

HLR/GR

VLR

PDN

Gb Gn Gi

SGSN

Gn

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 53

GPRS protocol architecture

apps.

IP/X.25

LLC

GTP

MAC

radio

MAC

radioFR

RLC BSSGP

IP/X.25

FR

Um Gb Gn

L1/L2 L1/L2

MS BSS SGSN GGSN

UDP/TCP

Gi

SNDCP

RLC BSSGP IP IP

LLC UDP/TCPSNDCP GTP

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 54

GPRS protocol architecture (Definitions)

Base station subsystem GPRS protocol (BSSGP)Convey routing and QoS-related information between BSS and SGSN

Subnetwork dependent convergence protocol (SNDCP)adapt to different characteristics of the underlying networks between SGSN and MStransport between GSNs within the GPRS backbone

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 55

Original Goals for 3G

Establish a common worldwide communication systemallowed for terminal and user mobility

Support the idea of universal personal telecommunication

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 56

UMTS and IMT-2000

Proposals for IMT-2000 (International Mobile Telecommunications)UWC-136, cdma2000, WP-CDMAUMTS (Universal Mobile Telecommunications System) from ETSI

UMTSUTRA (was: UMTS, now: Universal Terrestrial Radio Access)enhancements of GSM

EDGE (Enhanced Data rates for GSM Evolution): GSM up to 384 kbit/s– enhanced modulation schemes

CAMEL (Customized Application for Mobile Enhanced Logic)– intelligent network support

VHE (Virtual Home Environment)fits into GMM (Global Multimedia Mobility) initiative from ETSI

provide an architecture to integrate mobile and fixed terminals, many different access networks, and core transport networks

requirementsmin. 144 kbit/s rural (goal: 384 kbit/s)min. 384 kbit/s suburban (goal: 512 kbit/s)up to 2 Mbit/s urban

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 57

Frequencies for IMT-2000

IMT-2000

1850 1900 1950 2000 2050 2100 2150 2200 MHz

MSS↑

ITU allocation(WRC 1992) IMT-2000 MSS

Europe

China

Japan

NorthAmerica

UTRAFDD ↑

UTRAFDD ↓

TDD

TDD

MSS↑

MSS↓

DECT

GSM1800

1850 1900 1950 2000 2050 2100 2150 2200 MHz

IMT-2000 MSS↑

IMT-2000 MSS↓

GSM1800

cdma2000W-CDMA

MSS↓

MSS↓

MSS↑

MSS↑

cdma2000W-CDMAPHS

PCS rsv.

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 58

IMT-2000 family

IMT-DS(Direct Spread)

UTRA FDD(W-CDMA)

3GPP

IMT-TC(Time Code)UTRA TDD(TD-CDMA);TD-SCDMA

3GPP

IMT-MC(Multi Carrier)

cdma2000

3GPP2

IMT-SC(Single Carrier)

UWC-136(EDGE)

UWCC/3GPP

IMT-FT(Freq. Time)

DECT

ETSI

GSM(MAP)

ANSI-41(IS-634) IP-Network

IMT-2000Core NetworkITU-T

IMT-2000Radio AccessITU-R

Interface for Internetworking

Flexible assignment of Core Network and Radio Access

Initial UMTS(R99 w/ FDD)

IS-634: define the messaging interface between TDMA, BS, and MSC

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 59

GSM and UMTS Releases

19923.x.yPh1-Phase 1

19954.x.yPh2-Phase 2

early 19975.x.yR96-Phase 2+ Release 1996

early 19986.x.yR97-Phase 2+ Release 1997

early 19997.x.yR98-Phase 2+ Release 1998

8.x.y-Phase 2+ Release 1999March 2000

3.x.yR99

Release 1999-

9.x.y-Phase 2+ Release 2000Renaming…

4.x.yR00

Release 2000-

March 20014.x.yRel-4Release 4Phase 2+ Release 4

March - June 20025.x.yRel-5Release 5Phase 2+ Release 5

December 2004 -March 20056.x.yRel-6Release 6Phase 2+ Release 6

Freeze date(indicative only)

Spec versionnumberAbbreviated name3G ReleaseGSM/EDGE Release

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 60

GSM and UMTS Releases (Definitions)

Release 99new radio access technologies

Release 4introduces QoS in fixed network plus several execution environments and new service architectures

Release 5radically different core (all-IP) network

Release 6comprises the use of MIMO antennas, enhanced MMS, security enhancements, WLAN/UMTS interworking, broadcast/multicast services, enhanced IMS, IP emergency calls, and many more management features

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 61

Licensing Example: UMTS in Germany, 18. August 2000

Sum: 50.81 billion €

UTRA-FDD: Uplink 1920-1980 MHzDownlink 2110-2170 MHzduplex spacing 190 MHz 12 channels, each 5 MHz

UTRA-TDD: 1900-1920 MHz, 2010-2025 MHz; 5 MHz channels

Coverage of the population 25% until 12/200350% until 12/2005

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 62

UMTS architecture (Release 99 used here!)

UTRANUE CN

IuUu

UTRAN (UTRA Network)handles cell level mobilityRadio Network Subsystem (RNS)

radio channel ciphering and deciphering, handover control, radio resource management

Encapsulation of all radio specific tasksUE (User Equipment)

comprises all the functions needed to access UMTS servicesCN (Core Network)

Inter system handovergateways to other networks (fixed or wireless)

Location management if there is no dedicated connection between UE and UTRAN

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 63

UMTS domains and interfaces I

User Equipment DomainAssigned to a single user in order to access UMTS services

Infrastructure DomainShared among all usersOffers UMTS services to all accepted users

USIMDomain

MobileEquipment

Domain

AccessNetworkDomain

ServingNetworkDomain

TransitNetworkDomain

HomeNetworkDomain

Cu Uu Iu

User Equipment Domain

ZuYu

Core Network Domain

Infrastructure Domain

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 64

UMTS domains and interfaces II

Universal Subscriber Identity Module (USIM)Functions for encryption and authentication of usersLocated on a SIM inserted into a mobile device

Mobile Equipment DomainFunctions for radio transmission User interface for establishing/maintaining end-to-end connections

Access Network DomainAccess network dependent functions

Core Network DomainAccess network independent functionsServing Network Domain

Network currently responsible for communicationHome Network Domain

Location and access network independent functions

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 65

Spreading and scrambling of user dataConstant chipping rate of 3.84 Mchip/sDifferent user data rates supported via different spreading factors

higher data rate: less chips per bit and vice versaUser separation via unique, quasi orthogonal scrambling codes

users are not separated via orthogonal spreading codesspreading codes: separate different data streams of a sender

much simpler management of codes: each station can use the same orthogonal spreading codesprecise synchronisation not necessary as the scrambling codes stay quasi-orthogonal

data1 data2 data3

scramblingcode1

spr.code3

spr.code2

spr.code1

data4 data5

scramblingcode2

spr.code4

spr.code1

sender1 sender2

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 66

OSVF (Orthogonal Variable Spreading Factor) coding

1

1,1

1,-1

1,1,1,1

1,1,-1,-1

X

X,X

X,-X 1,-1,1,-1

1,-1,-1,11,-1,-1,1,1,-1,-1,1

1,-1,-1,1,-1,1,1,-1

1,-1,1,-1,1,-1,1,-1

1,-1,1,-1,-1,1,-1,1

1,1,-1,-1,1,1,-1,-1

1,1,-1,-1,-1,-1,1,1

1,1,1,1,1,1,1,1

1,1,1,1,-1,-1,-1,-1

SF=1 SF=2 SF=4 SF=8

SF=n SF=2n

...

...

...

...

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 67

UMTS FDD frame structure

W-CDMA• 1920-1980 MHz uplink• 2110-2170 MHz downlink• chipping rate:

3.840 Mchip/s• soft handover• QPSK• complex power control

(1500 power control cycles/s)

• spreading: UL: 4-256; DL:4-512

0 1 2 12 13 14...

Radio frame

Pilot FBI TPC

Time slot

666.7 µs

10 ms

Data

Data1

uplink DPDCH

uplink DPCCH

downlink DPCHTPC TFCI Pilot

666.7 µs

666.7 µs

DPCCH DPDCH

2560 chips, 10 bits

2560 chips, 10*2k bits (k = 0...6)

TFCI

2560 chips, 10*2k bits (k = 0...7)

Data2

DPDCH DPCCHFBI: Feedback InformationTPC: Transmit Power ControlTFCI: Transport Format Combination IndicatorDPCCH: Dedicated Physical Control ChannelDPDCH: Dedicated Physical Data ChannelDPCH: Dedicated Physical ChannelSlot structure NOT for user separation

but synchronisation for periodic functions!

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 68

Typical UTRA-FDD uplink data rates

481664Spreading

15151515DPCCH [kbit/s]

96048024060DPDCH [kbit/s]

3841446412.2 (voice)User data rate [kbit/s]

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 69

UMTS TDD frame structure (burst type 2)

TD-CDMA• 2560 chips per slot• spreading: 1-16• symmetric or asymmetric slot assignment to UL/DL (min. 1 per direction)• tight synchronisation needed• simpler power control (100-800 power control cycles/s)

0 1 2 12 13 14...

Radio frame

Data1104 chips

Midample256 chips

Data1104 chips

Time slot

666.7 µs

10 ms

Traffic burstGP

midample: training and channel estimation

GP: guard period96 chips

2560 chips

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 70

UTRAN architecture

UTRAN comprises severalRNSs

Node B can support FDD orTDD or both

RNC is responsible for handoverdecisions requiringsignalingto the UE

Cell offers FDD or TDD

RNC: Radio Network ControllerRNS: Radio Network Subsystem

Node B

Node B

RNC

Iub

Node B

UE1

RNS

CN

Node B

Node B

RNC

Iub

Node B

RNS

Iur

Node B

UE2

UE3

Iu

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 71

UTRAN architecture

RNC

Iub

RNS

CN

RNC

Iub

RNS

Iur

Iu

Node B

Node BNode B

Node BNode B

Node B

Node B

UTRAN comprises several RNSsNode B can support FDD or TDD

or both

RNC is responsible for handoverdecisions requiring signalingto the UE

Cell offers FDD or TDD

RNC: Radio Network ControllerRNS: Radio Network SubsystemUE

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 72

UTRAN functions

Admission controlCongestion controlSystem information broadcastingRadio channel encryptionHandoverSRNS movingRadio network configurationChannel quality measurementsMacro diversityRadio carrier controlRadio resource controlData transmission over the radio interfaceOuter loop power control (FDD and TDD)

minimize interference between neighbouring cells or control the size of a cellChannel codingAccess control

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 73

Core network: protocols

MSC

RNS

SGSN GGSN

GMSC

HLR

VLR

RNS

Layer 1: PDH, SDH, SONET

Layer 2: ATM

Layer 3: IPGPRS backbone (IP)

SS 7

GSM-CSbackbone

PSTN/ISDN

PDN (X.25),Internet (IP)

UTRAN CN

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 74

Core network: architecture

BTS

Node B

BSC

Abis

BTS

BSS

MSC

Node B

Node B

RNC

Iub

Node BRNS

Node BSGSN GGSN

GMSC

HLR

VLR

IuPS

IuCS

Iu

CN

EIR

GnGi

PSTN

AuC

GR

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 75

Core network

The Core Network (CN) and thus the Interface Iu, too, are separated into two logical domains:Circuit Switched Domain (CSD)

Circuit switched service incl. signalingResource reservation at connection setupGSM components (MSC, GMSC, VLR)IuCS

Packet Switched Domain (PSD)GPRS components (SGSN, GGSN)IuPS

Release 99 uses the GSM/GPRS network and adds a new radio access!Helps to save a lot of money …Much faster deploymentNot as flexible as newer releases (5, 6)

GSM circuit switched part replaced by all-IP core

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 76

UMTS protocol stacks (user plane)

apps. &protocols

MAC

radio

MAC

radio

RLC SAR

Uu IuCSUE UTRAN 3GMSC

RLC

AAL2

ATM

AAL2

ATM

SAR

apps. &protocols

MACradio

MACradio

PDCP GTP

Uu IuPSUE UTRAN 3GSGSN

RLCAAL5ATM

AAL5ATM

UDP/IPPDCP

RLC UDP/IP UDP/IP

Gn

GTP GTP

L2L1

UDP/IPL2L1

GTP

3GGGSN

IP, PPP,…

IP, PPP,…

IP tunnel

Circuitswitched

Packetswitched

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 77

UMTS protocol stacks (user plane): Definitions

AAL2Connection-oriented, synchronous VBR traffic

Packet data convergence protocol (PDCP)perform header compression to avoid redundant data transmission using scarce radio resources

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 78

Support of mobility: macro diversity

Multicasting of data via several physical channels

Enables soft handoverFDD mode only

Uplinksimultaneous reception of UE data at several Node BsReconstruction of data at Node B, SRNC or DRNC

DownlinkSimultaneous transmission of data via different cellsDifferent spreading codes in different cells

CNNode B RNC

Node BUE

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 79

Support of mobility: handover

From and to other systems (e.g., UMTS to GSM)This is a must as UMTS coverage will be poor in the beginning

RNS controlling the connection is called SRNS (Serving RNS)RNS offering additional resources (e.g., for soft handover) is called Drift

RNS (DRNS)End-to-end connections between UE and CN only via Iu at the SRNS

SRNC relocation: hard handoverChange of SRNS requires change of IuInitiated by the SRNSControlled by the RNC and CN

SRNC

UE

DRNC

Iur

CN

IuNode B

Iub

Node BIub

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 80

Example handover types in UMTS/GSM

RNC1

UE1

RNC2

Iur

3G MSC1

IuNode B1

IubNode B2

Node B3 3G MSC2

BSCBTS 2G MSC3

AAbis

UE2

UE3

UE4

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 81

UMTS/GSM Handover

Intra-node-B, intra-RNCUE moves from one antenna of node B to another antennasofter handover: node B performs combining and splitting of data streams

Inter-node-B, intra-RNCUE moves from one node B to another controlled by the same RNCRNC combines and splits data

Inter-RNCUE moves from one node B to another controlled by different RNCsinternal: not visible for the CNexternal: relocation of controlling RNC => hard handover

Inter-MSChard handover of the connection

Inter-systemUE moves from a 3G UMTS network into a 2G GSM networkhard handover

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 82

Breathing Cells

GSMMobile device gets exclusive signal from the base station Number of devices in a cell does not influence cell size

UMTSCell size is closely correlated to the cell capacitySignal-to-nose ratio determines cell capacityNoise is generated by interference from

other cellsother users of the same cell

Interference increases noise levelDevices at the edge of a cell cannot further increase their output power (max. power limit) and thus drop out of the cell

no more communication possibleLimitation of the max. number of users within a cell required

Cell breathing complicates network planning

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 83

Breathing Cells: Example

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 84

UMTS services (originally)

Data transmission service profiles

Virtual Home Environment (VHE)Enables access to personalized data independent of location, access network, and deviceNetwork operators may offer new services without changing the networkService providers may offer services based on components which allow the automatic adaptation to new networks and devicesIntegration of existing IN services

Circuit switched16 kbit/sVoiceSMS successor, E-MailPacket switched14.4 kbit/sSimple Messaging

Circuit switched14.4 kbit/sSwitched Dataasymmetrical, MM, downloadsCircuit switched384 kbit/sMedium MMLow coverage, max. 6 km/hPacket switched2 Mbit/sHigh MMBidirectional, video telephoneCircuit switched128 kbit/sHigh Interactive MM

Transport modeBandwidthService Profile

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 85

Example 3G Networks: Japan

FOMA (Freedom Of Mobile multimediaAccess) in Japan

Examples for FOMA phones

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 86

Example 3G networks: Australia

cdma2000 1xEV-DO in Melbourne/Australia

Examples for 1xEV-DO devices

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 87

Isle of Man – Start of UMTS in Europe as Test

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 88

UMTS in Monaco

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Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 89

UMTS in Europe

Vodafone/Germany

Orange/UK

Dr. Ka-Cheong Leung CSIS 7304 The Wireless Internet and Mobile Computing 90

Some current enhancements

GSMEMS/MMS

EMS: 760 characters possible by chaining SMS, animated icons, ring tones, was soon replaced by MMS (or simply skipped)MMS: transmission of images, video clips, audio

– see WAP 2.0 / chapter 10

EDGE (Enhanced Data Rates for Global [was: GSM] Evolution)8-PSK instead of GMSK, up to 384 kbit/snew modulation and coding schemes for GPRS EGPRS

– MCS-1 to MCS-4 uses GMSK at rates 8.8/11.2/14.8/17.6 kbit/s– MCS-5 to MCS-9 uses 8-PSK at rates 22.4/29.6/44.8/54.4/59.2 kbit/s

UMTSHSDPA (High-Speed Downlink Packet Access)

initially up to 10 Mbit/s for the downlink, later on 20 Mbit/s using MIMO- (Multiple Input Multiple Output-) antennasuses 16-QAM instead of QPSK