chap 11(gsm+umts)

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Introduction, History, Overview of Wireless Systems

1GSM + UMTSWireless CommunicationContentsIntroductionNetwork architecture Fundamental functionalityPhysical layer / radio interfaceUMTS

2GSM The idea of a common European mobile communications system1982: A Nordic group is considering the next generation of mobile telephone. NMT (Nordisk Mobil Telefon), the analogue first generation system has only just been startedThese ideas are presented to CEPT (European Conference of Postal and Telecommunications Administrations) in June 1982September 1982: The first meeting in CEPT GSM Groupe Spcial MobileIn 1988 ETSI (European Telecommunications Standards Institute) is established and the work is continued under a new name: SMG Special Mobile Group

GSM - SpecificationsOriginal specifications for the GSM system:Good subjective voice qualityLow terminal and service costSupport for international roamingSupport for handheld terminalsSupport for new servicesSpectrum efficientCompatible with ISDN

GSM - Growth1991: First operational GSM network in Finland: Radiolinja1993: Tele-mobil (later: Telenor Mobil) and NetCom GSM open their networks in Norway1998: GSM 1800 is deployed to increase capacity in cities and other densely populated areas02004006008001 0001 2001 4001 6001 8002 0002 2002 4002 6002 8003 0003 200198219831984198519861987198819891990199119921993199419951996199719981999 20000 %10 %20 %30 %40 %50 %60 %70 %80 %TM NMTTM GSMNetCom 9M01GSM improvements 2.5 G and 3 GThe need for data services increase:In 1998-99 the HSCSD High Speed Circuit Switched Data - is standardised. Introduced in Norway 1. July 2001 (Telenor)I 1999 packet switching using GPRS (General Packet Radio Service) is standardised. Introduced in Norway 1. February 2001 (Telenor)Theoretical data rates up to 171 kbit/s

"2.5 G" EDGE Enhanced Data rates for GSM EvolutionStandardised in 2001-2002Introduced in September 2004 Theoretical data rates up to 373 kbit/s3 G" EDGE Enhanced Data rates for GSM Evolution/UMTS

Standardised in 2001-2002Introduced in September 2004 deployment ongoing Theoretical data rates up to 2 Mbps

Some GSM terminalsDevelopment..HTC P4350Pocket computer running Windows

iPhone ApplesMobile phone initiativeHigh level network architecture (1/2)

SIMME:Mobile equipmentServices / ApplicationsCore Network(CN)Ext.networkUE: User equipmentAccess Network(AN)8High level network architecture (2/2)The network contains functionally of: User Equipment (UE), Access Network (AN), and Core Network (CN)User equipment: Interfaces the user, handles radio functionalityAccess network: Communication to and from the user equipment, handles all radio related functionality in the networkCore network: Communication between access network and external networks, handles all switching and routing

Services and applications lie above the network10GSMThe European TDMA Digital Cellular StandardGeneral Architecture Of GSM MESIMBTSBTSBSCBSCMSCVLREIRHLRAuCAUmAbisPSTN,ISDNMobile stationBase Station SubsystemNetworkSubsystem MSBSSNSNetwork Overview11

Network OverviewA GSM system is basically designed as a combination of three major subsystems: Network Sub-System (NSS), Radio subsystem called the Base station Sub-System (BSS),Operation Sub-System (OSS).

The Network Sub-System (NSS)

includes the equipment and functions related to end-to-end-calls, management of subscribers, mobility, and interfaces with the fixed network (PSTN). It is built on the switch of the system called Mobile-services Switching Center (MSC).

The Base station Sub-System (BSS)

includes the equipment and functions related to the management of the connection on the radio path. It mainly consists of Base Transceiver Stations (BTS) communicating with the Mobile Station (MS) and one Base Station Controller (BSC) managing the flow of information between the BTSs and the MSC.

12Network OverviewThe Operation Sub-System (OSS)mainly contains Operation and Maintenance Center for NSS (OMC-S) and Operation and Maintenance Center devoted to the BSS (OMC-R). It is connected to all equipment in the switching system and to the BSC (BTSs are not connected to the OSS).

13Mobile StationThe Mobile Station (MS) is composed of three parts:The handset includes the radio equipment (receiver-transmitter) and the Man-Machine Interface (MMI),The SIM card (Subscriber Identity Module-card): allows the identification of any subscriberThe battery.


Subscriber Identification

The International Mobile Subscriber Identity (IMSI) is the primary identification of the subscriber within the GSM network and is permanently assigned to him.

The Mobile Subscriber ISDN Number (MSISDN) is the number that the calling party dials in order to reach the GSM subscriber. It is used by the land networks to route calls toward an appropriate GSM network. MSISDN is stored in HLR.

15BSS ArchitectureThe Base Station Sub-System (BSS) is a set of equipment (aerials, transceivers and a controller) that is viewed by the Mobile Switching Center through a single A interface as being the entity responsible for communicating with mobile telephones or Mobile Stations (MSs) in a certain area.

The radio equipment of a BSS may be composed of one or more cells, such a BSS may contain one or more Base Transceiver Stations (BTSs).

The interface between the BSC and the BTSs is called an Abis interface16BSSBSC: Base station ControllerIt manages radio resources for one or more BTS.Allocation and De-allocation of channels.Transmitter power control.Handoff controlBTS : Base Transceiver stationIt defines the cell .It handles the radio link protocol with the mobile station

A BSS contains only one Base Station Controller (BSC).The function split is basically between a transmission equipment, the BTS, and the BSC.

17NSS Architecture18Network SubsystemMSC: Mobile Switching CenterHLR: Home Location RegisterVLR: Visitor Location registerAuC: Authentication CenterEIR: Equipment Identity RegisterBSCMSCVLREIRHLRAuCPSTN,ISDNNSS ArchitectureBSCs of a same area are connected to a switch. In a GSM system this switch is called MSC (Mobile Switching Center). MSCs are connected to each others.Mobile Switching center:(MSC)call set up/supervision/release/routingbilling information collectionmobility managementpaging, alertingconnection to BSC, other MSC and other local exchange networksAccess to HLR and VLRUsually, each MSC is associated to four databases.

The Visitor Location Register (VLR)memorizes information about the subscribers physically present in a geographic area. Temporary visitors databaseOne VLR per MSC

19NSS Architecture Home Location Register (HLR) One HLR per GSM operator Contains permanent database of all the subscribers in the networkcontains MSRN(mobile station routing no.)It is referred for every incoming call

Authentication Center (AuC): Provides securityAuthentication and encryption

The Equipment Identity Register (EIR) contains list of all the Mobile Equipment: it contains valid and invalid mobile equipment.Contains IMEI

20Identification of users:Mobile number: MS-ISDN number follows numbering plan for telephony/ISDN (max. 15 digits):

Calling number associated with a subscriptionUsed on interface towards users

Identification of a mobile subscription:IMSI : International Mobile Subscription Identity

Identification of terminal:IMEI : International Mobile Equipment Identity. Not used in fundamental service handling, but to identify stolen or black listed equipmentIdentifying users and mobile terminals MCC [3]mobile country codeSubscription Identification NC[2-3]network codeCountry codeNational mobile number(1- 3)Fundamental functionality The following functions are described:Circuit switched connectivityPacket switched connectivityMobile messagingSecurityRoamingChoice of networkLocation updateHandover

Circuit Switched connectivity

ISDNMobile networkFixed connection and reserved resources while the communication lasts. (Mobile) telephony Circuit switched data, e.g. WAP, mobile office solutions using data cards etc. Transparent channel with defined performanceBilling typically per time unit and dependant on transport data rateStandard GSM: up to 14.4 kbit/s (more using HSCSD - High Speed Circuit Switched Data)

Packet Switched connectivityResources allocated only when data is transferred Same path through network can be maintained (but not necessarily)Billing typically dependant on amount of data transferred (or fixed tarrifs)GPRS: Theoretically up to 171 kbit/s, typically 40 50 kbit/s4 different quality classes for packet bearer services:

Internet ordifferent IP networkMobile networkBackgroundTypically automatic download of email, MMSInteractiveTypically web/WAP-browsing, MMS, games StreamingNetwork radio, video streaming, web TVConversationalVoice, video conferencing

Mobile messaging formats SMS: Short Message ServiceText based service to transfer up to 160 characters per message (solutions exist to connect messages into longer messages, and also to carry other types of content ring tones, logos)

MMS: Multimedia Messaging ServiceA service for multimedia content, such as text, picture, sound, video

Both SMS and MMS are store and forward services, i.e. messages are intermediately stored in the network

Security functionsThe purpose of security functions is to protect users and network against improper and illegal use:Verify that the user has a valid subscriptionProtect the users identity against trackingProtection against wiretapping on the radio connection

The mechanisms in GSM are based on secure storage of information in the users SIM card

International networkRoaming (1/2)Circuit switched call to a mobile in