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GSM vs. CDMA

GSM vs. CDMA. Comparing the two most prevalent mobile communication technologies. What is …?. GSM (Global System for Mobile Communication) Based on TDMA technology Mainly used in Europe, Middle-east and Africa. CDMA (Code Division Multiple Access) Based on a spread-spectrum technology

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GSM vs. CDMA

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  1. GSM vs. CDMA Comparing the two most prevalent mobile communication technologies

  2. What is …? • GSM (Global System for Mobile Communication) • Based on TDMA technology • Mainly used in Europe, Middle-east and Africa • CDMA (Code Division Multiple Access) • Based on a spread-spectrum technology • Mainly used in North America

  3. Power Time CH 3 Frequency CH 4 Technology: FDMA • Transmission over Radio Frequency (800MHz – 1900MHz) • Frequency Division Multiple Access • An analog system. Each user is given one channel (i.e., one frequency). Bad utilisation. CH 2 CH 1

  4. GSM uses TDMA (Time Division Multiple Access) CDMA is a "spread spectrum" technology, allowing many users to occupy the same time and frequency allocations in a given band/space. Each mobile station has a unique digital code. The signals are spread over the entire spectrum of 1.25MHz unlike FDMA/TDMA. Technology: TDMA Power Time Frequency Channel 3 Channel 4 Channel 1 Channel 2

  5. Spectrum • Mobile communication uses Radio Frequency (RF) • GSM uses frequencies 824 – 849 MHz (25 MHz band) and 869 – 895 MHz (25 MHz band)

  6. Cellular Architecture HLR BSC A Abis VLR Um PSTN MSC BSC EIR AuC BTS Mobile Station Base Station Subsystem Network Subsystem

  7. Cell Site Cells • The coverage area is divided into hexagonal cells • A BTS is situated at three of the vertices of each cell • In USA, the spectrum in each cell is divided into two bands: A-band and B-band, each 25 MHz • Each 25 MHz band is divided into 832 30 kHz channels • Two channels separated by 45 MHz forms a full-duplex channel • The number of channels used in a cell varies from as low as 4 to as many as 80

  8. GSM Frames and Burst periods BP – Burst Period TCH – Traffic Channel SACCH – Assoc. Control Channel

  9. Handover/Handoff • Internal Handovers (only one BSC involved) • Channels in the same cell • Cells under the same BSC • External Handovers (involved the MSC) • Cells under different BSCs under the same MSC • Cells under different MSCs (anchor MSC and relay MSC) • Techniques used: • Minimum acceptable performance: increase power i.s.o. handover • Power budget: handover i.s.o. increasing power

  10. Services • SMS (Short Message Service) http://www.gsmworld.com/technology/sms/intro.shtml • Facsimile (for receiving fax on a mobile station) • WAP (Wireless Application Protocol) – a standard to let wireless equipment access the Internet. A Wireless Markup Language (WML) is used to encode the pages instead of HTML. • MMS (Multimedia Message Service) • EDGE (Enhanced Data rates for GSM evolution) • The ever elusive “Killer app”

  11. Group Spéciale Mobile Cellular services started in Europe in 1982 13 operators in Europe sign a MoU in 1987 Radiolinja Oy became the first GSM network operator in 1992 cdmaOne (2G) IS-95A (First CDMA cellular standard) First deployed in Sep 1996 by Hutchison IS-95B (2.5G) First deployed in Sep 1999 in Korea CDMA2000 (3G) CDMA2000 1X (Phase 1) Deployed in Korea in 2000 CDMA2000 1x EV-DO CDMA2000 1x EV-DV History and proponents

  12. GSM coordinated by 3GPP Release 99 Release 4 (was Release 2000) W-CDMA (Widebad CDMA) coordinated by 3GPP2 B-CDMA (Broadband CDMA) cdmaOne (2G) IS-95A 1.25MHz CDMA channels circuit switched data connections at 14.4kbps IS-95B (2.5G) CDMA2000 (3G) CDMA2000 1X (Phase 1) Standards and standardization

  13. Over 1 billion GSM subscribers Over 170 million CDMA subscribers Statistics (Geography-wise)

  14. Statistics (Subscriber growth)

  15. Glossary • GPRS – General Packet Radio Service; GPRS represents first implementation of packet switching within GSM, precursor to 3G • GGSN – Gateway GPRS Support Node; the gateway between the cellular network and the IP network

  16. References • GSM Association website, at http://www.gsmworld.com • CDMA Development group, at http://www.cdg.com • UMTS World, at http://www.umtsworld.com • How Stuff Works: Cell Phones, at http://electronics.howstuffworks.com/cell-phone.htm • Cellular Telephone Basics, at http://www.privateline.com/Cellbasics/Cellbasics.html • GSM overview, at http://ccnga.uwaterloo.ca/~jscouria/GSM/gsmreport.html

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