Members of our Presentation  (Bsts09-08) Hafiz Umer Ejaz  (Bsts09-09) Rai-Habib Ullah  (Bsts09-31) M.Arsalan Qureshi  (Bsts09-32) Shoaib Ansari  (Bsts09-34) Talal Rashid

Presentation

Why do we need cellular phones? We can freely move and in contact with people at anytime. It helps to organize our life. If someone lost, it can give you directions.

Advantages of cellular phone Advantages to Mobile User Advantages to Network Provider

Different technologies of Cellular phones First Generation -Analog Mobile Telephone System Second Generation-Digital Mobile Communication System Third Generation-IMT-2000

Cellular technologies overview

First Generation Cellular Systems The predominant technology of first generation was Advanced Mobile Phone System or AMPS. First generation cellular systems made its entrance in 1979, work in 1980’s were based on analog communication. On October 12, 1983 the regional Bell operating company began the first United States commercial cellular service in Chicago.

Advanced Mobile Phone System (AMPS) is one of the leading analog cellular systems in North America. It uses FDMA to separate channels in a link.

BAND AMPS was released in 1983 using the 800-MHz to 900-MHz frequency band The System uses two separate analog channels The band between 824 and 849 MHZ carries reverse communication and the band between 869 and 894 MHZ carries forward communications

Total Access Communications Service The original European 900 MHz analog system launched in 1985 by Vodafone. Still used in Austria, Bahrain, China, Japan etc Uses a protocol known as Frequency Division Multiple Access (FDMA).

Nordic mobile telephony (NMT) It uses 450 and 900 MHz band. Still used in parts of Europe and Asia, including Algeria, Andorra, Bangladesh etc. It was the first cellular system to be used commercially.

Problems in First Generation As 1G was based on (FDMA) for transfer between cells, it was very vague and had a low capacity. It has a low degree of safety, Low security, easy to fake Poor data communication. Bulky equipment.,

Do you remember 1G phones?

Basic technologies CDMA (Code division multiple access) TDMA (Time division multiple access)

History & Introduction of GSM In 1982, the European Conference of Postal and Telecommunications Administrations (CEPT) created the GSM. In 1989, GSM responsibility was transferred to the European Telecommunications Standards Institute (ETSI). The first GSM network was launched in 1991 in Finland.

Main features of GSM Compatibility with other systems Flexibility and Increased Capacity Improved Security and privacy ISDN Compatibility

GSM Services Speech Services Bearer or Data Services Supplementary services

Speech Services Telephony Emergency Calls Dual Personal and Business Numbers

Bearer Data Services Short Message Service (SMS). Text files and fax. Voice mail.

Supplementary Services Number Identification Call Forwarding Call Waiting Call Hold etc

GSM Specifications GSM 900 * Mobile to BTS (uplink): MHz * BTS to Mobile (downlink): MHz EGSM900 * Mobile to BTS (uplink): 880~915MHz * BTS to Mobile (downlink): 925~960MHz EGSM MHz GSMEGSMGSM

GSM Specifications DCS (Digital Communication System) 1800 * Mobile to BTS (uplink): MHz * BTS to Mobile (downlink) MHz Base Station Receive MHz Base Station Transmit

GSM System Architecture Overview (MS) Mobile Station (BSS) Base Station Sub-system (NSS) Network and Switching Sub-system

The GSM Mobile Station (MS) Mobile Equipment (ME) Subscriber Identity Module (SIM)

Mobile Equipment International Mobile Equipment Identifier (IMEI) 160 character long SMS The IMEI may be used to block stolen equipment

Subscriber Identity Module (SIM) International mobile subscriber identifier (IMSI) Allows user to send and receive calls and receive other subscribed services SIM is Protected by 4-8 digit PIN PUK – Personal/Pin Unlocking Key

Base Station Subsystem (BSS) (BTS) Base Transceiver Station (BSC) Base Station Controller (XCDR) The Transcoder

Base Transceiver Station (BTS) General Architecture *Radio Transceivers *Combiner *Duplexer *Antennas and feeder cables

Rack Structure

Signal Flow in BTS Rack

Base Station Controller (BSC) Main functions of BSC * Allocates a channel for the duration of a call * Handles call set up * Maintains the call * Monitoring quality * It communicates with MSC,BTS & NSS. *Controls one or more BTSs The Transcoder

Network and Switching Sub-system (MSC) Mobile Switching Center (HLR) Home Location Register (VLR) Visitor Location Register (EIR) Equipment Identity Register (AUC) Authentication Center (GMSC) Gateway Mobile Switching Centre (EC) Echo Canceller Billing

Mobile Switching Center (MSC) Heart of the network Manages communication between GSM and other networks Call setup function and basic switching Call routing Billing information and collection Mobility management * Location Updating

Home Location Registers (HLR) Permanent database about mobile users in a large service area Database contains Subscriber ID Current subscriber VLR Subscriber status Authentication key

Visitor Location Registers (VLR) Temporary database which updates whenever new MS enters its area, by HLR database Controls those mobiles roaming in its area Reduces number of queries to HLR Database contains Mobile Status Location Area Identity(LAI)

Equipment Identity Register (EIR) Database that is used to track handsets using the IMEI (International Mobile Equipment Identity) Made up of three sub-classes: * White List * Black List * Gray List

Authentication Center (AUC) Protects against intruders in air interface Maintains authentication keys and algorithms and provides security. Generally associated with HLR

Gateway Mobile Switching Centre The GMSC is a device which routes traffic entering a mobile network to the correct destination. The GMSC accesses the network’s HLR to find the location of the required mobile user. A particular MSC can be assigned to act as a GMSC. The operator may decide to assign more than one GMSC. The GMSC routes calls out of the network and is the point of access for calls entering the network from outside.

Echo Canceller An echo canceller models the voice signal passing through it As the voice passes back through the canceller it applies signal to remove it dynamically.

Billing The MSC/GMSC that originates a call generates a record (Call Detail Record which contains: > Subscriber identity > Number called > Call length > Routing of the call The record passes along the backbone to the home network Billing computer generates bills to be sent to the user.