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Gsm cdma1
- 1. GSM Vs. CDMA AnOverview Bhushan G. Jagyasi Lecturer, Elex & Tele Comm Dept. Thadomal Shahani Engineering College
- 2. Classification Of ExistingSystems Technologies TDMA/FDMA CDMA GSM (European Standard) IS 136 (U.S Standard) PDC (Japnese Standard) IS 95 (U.S Standard)
- 3. Evolution Chart Years Service type Multi media Voice Analog AMPS Digital IS95 IS 136 GSM IMT 2000 Wireless Internet Mobile system ~ 24kbps ~64kbps ~2Mbps ~20Mbps 1980 1990 2000 2010 1G 2G 3G 4G Narrow Band Wide Band Broad Band
- 4. Access technology Time TimeTime Freq Freq Freq PN Code FDMA TDMA CDMA
- 5. Comparison BetweenTechnologies Digital Mobile technology User’s Dec-02 User’s Dec-03 Growth in2003 % GrowthShare Of Growth CDMA 145.2 181.0 35.4 24.3% 15.6% GSM 790.5 970.8 180.3 22.8% 79.5% PDC 60.1 63.1 3.0 5.0% 1.3% TDMA 107.4 113.0 5.5 5.1% 2.4% 3 GSM (W CDMA) 0.2 2.8 2.6 1708.5% 1.2% GLOBAL USER BASE 1103.7 1330.6 226.9 20.69% 100%
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- 7. GSM The European TDMADigital Cellular Standard • Services Provided By GSM 1. Telephony - Basic Teleservice 2. Other Services -Emergency calling -Voice Messaging
- 8. GSM The European TDMADigital Cellular Standard Services Provided By GSM (Cont..) 3. Bearer Services - Low Speed data transfer (upto 9.6 Kbps) -Group 3 Fax and Sms 4. Suplementary Services - call offering , call forwarding, call restriction, call waiting, call hold. - Multiparty teleconferencing, special schemes
- 9. GSM The European TDMADigital Cellular Standard • General Architecture Of GSM ME SIMSIM BTSBTS BTSBTS BSCBSC BSCBSC MSC VLR EIR HLR AuC AUm Abis PSTN, ISDN Mobile station Base Station Subsystem Network Subsystem MS BSS NS
- 10. GSM The European TDMADigital Cellular Standard • Mobile Station (MS): Two Blocks – Mobile Equipment (ME) – Subscribers Identity Module (SIM) Function of Mobile Station: 1. Personal Mobility
- 11. SIMSIM SIM GSM The EuropeanTDMA Digital Cellular Standard Function of Mobile Station: 1. Personal Mobility SIM SIMSIM SIM
- 12. GSM The European TDMADigital Cellular Standard • Mobile Station (MS): Two Blocks – Mobile Equipment (ME) – Subscribers Identity Module (SIM) Function of Mobile Station: 1. Personal Mobility 2. IMEI (International Mobile Equipment Identity) 3. IMSI (International Mobile Subscriber Identity)
- 13. GSM The European TDMADigital Cellular Standard • Base Station Subsystem (BSS) – Base Transceiver Station (BTS) – Base Station Controller (BSC) BSC
- 14. GSM The European TDMADigital Cellular Standard BSC BSC: Base station Controller 1. It manages radio resources for one or more BTS. 2. Allocation and Deallocation of channels. 3. Transmitter power control. 4. Handoff control BTS : Base Tranceiver station 1. It defines the cell . 2. It handles the radio link protocol with the mobile station
- 15. GSM The European TDMADigital Cellular Standard • Network Subsystem – MSC: Mobile Switching Center – HLR: Home Location Register – VLR: Visitor Location register – AuC: Authentication Center – EIR: Equipment Identity Register BSCBSC MSC VLR EIR HLR AuC PSTN, ISDN
- 16. GSM The European TDMADigital Cellular Standard • Mobile Switching center:(MSC) – call set up/supervision/release – call routing – billing information colllection – mobility management – paging, alerting, echo cancellation – connection to BSC, other MSC and other local exchange networks – Access to HLR and VLR
- 17. GSM The European TDMADigital Cellular Standard • Home Location Register (HLR) – One HLR per GSM operator – Contains permanent database of all the subscribers in the network – contains MSRN(mobile station routing no.) – It is reffered for every incomming call
- 18. GSM The European TDMADigital Cellular Standard • Visitor Location Register(VLR) – Temporary visitors database – One VLR per MSC • Authentication Center(AuC) – Provides security – Authentication and encryption • Equipment Identity Register: – Contains IMEI
- 19. GSM The European TDMADigital Cellular Standard BSC BSC MSC MSC VLR VLR HLR GMSC PSTN. ISDN Location Update
- 20. GSM The European TDMADigital Cellular Standard • Mobile call originating BSC BSC MSC MSC VLR VLR HLR GMSC PSTN. ISDN
- 21. GSM The European TDMADigital Cellular Standard • Mobile call terminating BSC BSC MSC MSC VLR VLR HLR GMSC PSTN. ISDN
- 22. GSM The European TDMADigital Cellular Standard • Handoff BSCBSC BSC MSC MSC GMSC Handoff is of 3 types 1. Intra BSC 2 Inter BSC 3. Inter MSC
- 23. GSM The European TDMADigital Cellular Standard • GSM Radio Aspects : Uplink(Mobile to base) • 890-915 MHz (Total 25 MHz) Downlink ( Base to Mobile) • 935-960 MHz (Total 25 MHz) Total 45 MHz spacing for duplex operation GSM uses TDMA and FDMA
- 24. GSM The European TDMADigital Cellular Standard • GSM Using FDMA Uplink Freq 890MHz 915Mhz 200KHz 1 2 3 4 5 124 Total Frequency range(Uplink)=25Mhz Spacing between two carriers= 200kHz No. of Carriers=25MHz/200KHz = 124
- 25. GSM The European TDMADigital Cellular Standard • GSM Using TDMA – TDMA Frame is divided into 8 time slots. 0 71 2 4 5 0 33 3 5 6 7 Time Freq Down Link carrier Up Link carrier 45MHz 200 KHz Time slots 4.6 ms 0.57ms 3 6 5421
- 26. GSM The European TDMADigital Cellular Standard • Classification of channels in GSM • Two types – Traffic channels (TCH) – Control channels (CCH) Channels are used to carry speech , data and control information. Traffic Channels are defined using 26 TDMA frame multiframe.
- 27. GSM The European TDMADigital Cellular Standard • Length of 26 TDMA frames = 120 msec • Length of 1 TDMA frame =120/26 = 4.615 msec • 1 TDMA frame consists of 8 burst frames • Length of 1 burst frame = 0.577msec • Out of 26 frames – 24 are TCH used for traffic – 1 is SACCH used for control – 1 is unused
- 28. GSM The European TDMADigital Cellular Standard 0 1 2 653 7 1 2 2524 4 0 10 3 57 57261 Data DataTraining Tdma Frame Frame Multiframe Format of a single Burst Duration=120ms Duration=4.615ms Duration=0.577ms 25
- 29. GSM The European TDMADigital Cellular Standard • Speech coding – Speech is digitized by PCM, o/p of PCM is 64Kb/s – It is further reduced by Regular pulse excited- Linear predictive coder, bit rate achieved 13kb/s for full rate (260 bits in 20 msec) – Further encoded for error correction, 456 bits per 20 msec, bit rate = 22.8 Kb/s – 456 bits are divided into 8 blocks and transmitted during 8 burst periods.
- 30. GSM The European TDMADigital Cellular Standard • Classification of Channels • 1 Traffic (TCH) – Speech • Full rate 22.8 kb/s • Half rate 11.4 kb/s – Data • 9.6kb/s • 4.8kb/s • 2.4kb/s
- 31. GSM The European TDMADigital Cellular Standard • 2 Control (CCH) – Broadcast (BCCH) • Freq correction (FCCH) • Synchronization (SCH) – Common (CCH) • Paging (PCH) • Access grant (AGCH) • Random Access (RACH) – Dedicated (DCCH) • Fast Associative (FACCH) • Slow Associative (SACCH) • Stand alone (SDCCH)
- 32. GSM The European TDMADigital Cellular Standard • GSM Security A3 A8 A3 A8 EqualSRES Kc Ki Ki Random no Ki Ki SRES Kc MS NETWORK
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- 34. CDMA • Classification ofCDMA Systems CDMA one CDMA 2000 IS95 IS95B JSTD 008 Narrow Band Wide Band CDMA SYSTEMS
- 35. CDMA • Multiple Accessin CDMA: – Each user is assigned a unique PN code. – Each user transmits its information by spreading with unique code. – Direct Sequence spread spectrum is used. – Users are seperated by code not by time slot and freq slot.
- 36. CDMA • Concept ofCDMA Users share same bandwidth User axis shows cumulative signal strength of all users Code 1 Code2 Code 3 Code 4 Freq User
- 37. CDMA • Spread Spectrumand Multiple Access: – Spread Spectrum • In Spread spectrum data is transmitted with BW in excess to minimum BW necessary to send it. • Spread spectrum is achieved by spreading with PN code at transmitter . Same code is used to despread the received signal at reciever – How do we get increased spectrum X Narrow band inputsignal Wide band code seq Wide band Spreaded seq
- 38. CDMA • Advantages ofspread spectrum: – Multipath Rejection – Immunity to interference and jamming – Multiple access Code 1 Code2 Code 3 Code 4 Freq User
- 39. CDMA • Comparison betweenCDMA and TDMA/FDMA: In TDMA Band width available for transmission is small which leads to compromise in quality of transmission. Whereas in CDMA systems entire spectrum is used which enhances voice quality. In TDMA/FDMA, cell design requires more frequency planning which is tough job. Whereas in CDMA frequency planning is minimal. TDMA is Band limited system. CDMA is Power limited system
- 40. CDMA • Types ofCodes used in CDMA: – Walsh code • Orthogonal codes • In IS 95A and IS 95B 64 Walsh codes are used • In CDMA 2000 128 Walsh codes are used – Short PN code(16 bit) • Used to identify the BS and hence the cell – Long PN code(42 bit code) • Used to identify mobile station on reverse link
- 41. CDMA • Formation ofchannels (IS 95) – PN Code( Chip code) has rate of 1.23 MHz – Chip rate = 1.23 MHz (spread BW) Link Forward Link (BS to MS) Reverse link (MS to BS)
- 42. CDMA • Forward Link(BS to MS) Forward CDMA Channels PILOT SYNC PAGE PAGE TRAFFIC TRAFFIC TRAFFIC DATA POWER CNTRL SUB CH W0 W32 W1 W7 W9 W0
- 43. CDMA • Reverse LinkChannel (BS to MS) – Here CDMA ch does not follow strictly orthogonal rule. – It consists of 242 logical channels. 42 bit long PN code is used to distinguish between channels. Reverse CDMA Channels Access Ch 1 Access Ch n Traffic Ch 1 Traffic Ch m m mobiles tryin to gain access to system m mobiles engaged in calls
- 44. CDMA • Other keyFactors – Diversity • Time diversity • Frequency diversity • Space(Path) diversity – Power Control – Handoff: It supports Soft Handoff
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