GSM(Global System For Mobile) Communication

GSM(Global System For Mobile) Communication

1. GSM Presented by- Navin A Seminar on

2. GSM (Global System for Mobile Communications, originally Groupe Special Mobile), is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation (2G) digital cellular networks used by mobile, first deployed in Finland in July 1991 . What is GSM ? "GSM" is a trademark owned by the GSM Association.

3. The GSM study group aimed to provide the followings through the GSM: Improved spectrum efficiency. International roaming. Low-cost mobile sets and base stations (BSs). High-quality speech. Compatibility with Integrated Services Digital Network (ISDN) and other telephone company services. Support for new services Why GSM ?

4. Tele-services Bearer or Data Services Supplementary services GSM SERVICES

5. • Telecommunication services that enable voice communication via mobile phones • Offered services - Mobile telephony - Emergency calling Tele Services

6. Voice mailbox Electronic mail Include various data services for information transfer between GSM and other networks like PSTN, ISDN etc. at rates from 300 to 9600 kbps Short Message Service ( SMS),alphanumeric data transmission to/from the mobile terminal. Bearer Services

7. Call related services : Call Waiting- Notification of an incoming call while on the handset Call Hold- Put a caller on hold to take another call Call Barring- All calls, outgoing calls, or incoming calls Call Forwarding- Calls can be sent to various numbers defined by the user Multi Party Call Conferencing - Link multiple calls together CLIP – Caller line identification presentation CLIR – Caller line identification restriction Supplementary Services

8. GSM Specification Two main standard of GSM :- GSM 900 – Designed for extensive radio coverage in rural areas GSM 1800 – Designed for radio coverage in areas with very high subscriber density. RF Spectrum GSM 900 Mobile to BTS (uplink): 890-915 MHz BTS to Mobile(downlink):935-960 MHz Bandwidth : 2* 25 MHz GSM 1800 Mobile to BTS (uplink): 1710-1785 MHz BTS to Mobile(downlink) 1805-1880 MHz Bandwidth : 2* 75 MHz

9. Cell is the radio coverage area of one base transceiver station Cellular Networking technology that breaks geographic area into cells shaped like honey comb 1 2 3 4 5 6 7 6 7 2 1 5 GSM Concepts - Cellular Structure

10. Why a hexagon and not other geometrical shape represent cells? When showing a cellular system we want to depict an area totally covered by radio, without any gaps. T he circles leave gaps Also for a given area, among square, triangle and hexagon, radius of a hexagon will be the maximum which is needed for weaker mobiles.

11. GSM SYSTEM ARCHITECTURE

12. 4 Basic interconnected Subsystem : Mobile Station (MS) Base station Subsystem (BSS) Network and Switching Subsystem (NSS) Operation Support Subsystem (0SS)

13. Mobile Station (MS) The Mobile Station is made up of two entities : Mobile Equipment ( ME) Subscriber Identity Module (SIM) Mobile Equipment Voice and data transmission Portable, vehicle mounted, hand held device Uniquely identified by an IMEI (International Mobile Equipment Identity).

14. Subscriber Identity Module (SIM ) Portable Smart Card with memory (ROM-6KB to 16KB-A3/A8 algorithm, RAM- 128KB TO 256KB, EEPROM- 3KB to 8KB ) Static Information International Mobile Subscriber Identity(IMSI ) is the unique 15 digit( 3 for country code, 3 for mobile network code and 9 for mobile ID )identity number resides in SIM. Personal Identification Number (PIN) Authentication Key ( Ki) Dynamic Information Temporary Mobile Subscriber Identity(TMSI) Location Area Identity (LAI) Phone memories, billing information Ability to store Short Messages received

15. Base Station Subsystem is composed of two parts that communicate across the standardized Abis interface allowing operation between components made by different suppliers Base Transceiver Station ( BTS) Base Station Controller (BSC) Base Station Subsystem (BSS) Base Transceiver Station ( BTS ) Base Station Controller (BSC)

16. Base Transceiver Station (BTS): Encodes, encrypts, multiplexes, modulates and feeds the RF signals to the antenna. Communicates with Mobile station and BSC Consists of Transceivers (TRX) units Base Station Controller ( BSC): Manages Radio resources for BTS Assigns Frequency and time slots for all MS’s in its area Handles call set up Transcoding and rate adaptation functionality Handover for each MS Radio Power control It communicates with MSC and BTS

17. Mobile Switching Centre (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 - Registration - Location Updating - Inter BSS and inter MSC call handoff Network Switching Subsystem(NSS) MSC

18. Home Location Registers (HLR) Permanent database about mobile subscribers in a large service area(generally one per GSM network operator) database contains IMSI ,MSISDN , prepaid/post-paid , roaming restrictions , supplementary services. 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 IMSI , TMSI,MSISDN,MSRN,Location Area , authentication key

19. The OSS (Operation Subsystem) enables centralized operation, management, and maintenance of all GSM subsystems Components Operation and Maintenance Center (OMC ) Mainly does three operation 1.To maintain all telecommunication hardware and network operation with a particular market. 2. Manage all charging and billing procedure 3.Manage all mobile equipment in the system. Operation Support System (OSS )

20. Authentication Centre (AUC) Protects against intruders in air interface Maintains authentication keys and algorithms and provides security triplets ( RAND , SRES ,Kc) Equipment Identity Register (EIR) Database that is used to track handsets using the IMEI (International Mobile Equipment Identity) Made up of three sub-classes: The White List, The Black List and the Grey List

21. GSM Frame Structure

22. Speech decoding Channel decoding De-interleaving Burst Formatting De-ciphering Demodulation Modulation Ciphering Burst Formatting Interleaving Channel Coding Speech coding Radio Interface Speech Speech 13 Kbps 22.8 Kbps 22.8 Kbps 33.6 Kbps 33.6 Kbps 270.83 Kbps GSM Operation from transmitter to receiver

23. Example: GSM location update (1) ME SIM HLR MSC VLR 1 Most recently allocated Temporary Mobile Subscriber Identity (TMSI ) and last visited LAI (Location Area ID) are stored in SIM even after switch-off. After switch-on, MS monitors LAI. If stored and monitored LAI values are the same, no location updating is needed. (most generic scenario) MSC VLR 2 LAI 1 IMSI TMSI LAI 1 IMSI TMSI IMSI LAI 1 (in broadcast messages)

24. GSM location update (2) ME SIM MSC VLR 1 Different LAI values => location update required ! MSC VLR 2 LAI 2 HLR IMSI LAI 1 IMSI TMSI LAI 1 IMSI TMSI (in broadcast messages)

25. GSM location update (3) ME SIM MSC VLR 1 SIM sends old LAI and TMSI to VLR 2. VLR 2 does not recognize TMSI since there is no TMSI-IMSI context. Who is this user? MSC VLR 2 LAI 1, TMSI HLR IMSI LAI 1 IMSI TMSI LAI 1 IMSI TMSI No TMSI - IMSI context

26. GSM location update (4) ME SIM MSC VLR 1 However, VLR 2 can contact VLR 1 (address: LAI 1) and request IMSI. IMSI is sent to VLR 2. MSC VLR 2 HLR IMSI LAI 1 IMSI TMSI LAI 1 IMSI TMSI IMSI TMSI IMSI address: LAI 1

27. GSM location update (5) ME SIM MSC VLR 1 Important: HLR must be updated (new LAI). If this is not done, incoming calls can not be routed to new MSC/VLR. HLR also requests VLR 1 to remove old user data. MSC VLR 2 HLR IMSI LAI 1 LAI 2 IMSI TMSI LAI 1 IMSI TMSI IMSI TMSI LAI 2

28. GSM location update (6) ME SIM MSC VLR 1 VLR 2 generates new TMSI and sends this to user. User stores new LA2 and TMSI safely in SIM. Location update successful ! MSC VLR 2 HLR IMSI LAI 2 LAI 1 IMSI TMSI LAI 2 TMSI IMSI TMSI TMSI LAI 2 TMSI

29. MS sends dialled number to BSS BSS sends dialled number to MSC MSC checks VLR if MS is allowed the requested service. If so, MSC asks BSS to allocate resources for call. MSC routes the call to GMSC GMSC routes the call to local exchange of called user. Answer back(ring back) tone is routed from called user to MS via GMSC,MSC,BSS Outgoing Call Call Originating from MS Call termination to MS Call Routing

30. Incoming Call Calling a GSM subscribers Forwarding call to GSMC Signal Setup to HLR 5. Request MSRN from VLR Forward responsible MSC to GMSC Forward Call to current MSC 9. Get current status of MS 11. Paging of MS 13. MS answers 15. Security checks 17. Set up connection

31. ADVANTAGES OF GSM :- It can be use repeaters. It is easy to implement. International roaming is not a big problem . DISADVANTAGES OF GSM:- Manufactures are not release IS-95 devices due to the lack of the big market and it come in late in market. GSM has fixed max call sites range up to 35 km that is very limited.

32. Development of the Market Share of Mobile Standards Mobile phone subscribers by technology (left Y axis) and total number of subscribers globally (right Y axis) In a fast-growing market, GSM/3GSM (red) grows faster than the market and is gaining market share, the CDMA family (blue) grows at about the same rate as the market, while other technologies (grey) are being phased out.

33. GSM in India

34. 2nd Generation GSM -9.6 Kbps (data rate) 2.5 Generation ( Future of GSM) HSCSD (High Speed ckt Switched data) Data rate : 76.8 Kbps (9.6 x 8 kbps) GPRS (General Packet Radio service) Data rate: 14.4 - 115.2 Kbps EDGE (Enhanced data rate for GSM Evolution) Data rate: 547.2 Kbps (max ) 3 Generation WCDMA(Wide band CDMA) Data rate : 0.348 – 2.0 Mbps 3.5 Generation High Speed Downlink Packet Access(HSDPA) Data rate : 1.4– 5.8 Mbps 4 Generation Long Term Evolution (LTE) Data rate : up to 20.0 Mbps FUTURE OF GSM