1. Multiple Access Protocol ผศ. ดร. อนันต์ ผลเพิ่ม Asst.Prof.Anan Phonphoem, Ph.D. anan@cpe.ku.ac.th http://www.cpe.ku.ac.th/~anan Computer Engineering Department Kasetsart University, Bangkok, Thailand

2. Multiple access protocols

3. Random Access Evolution MA Multiple access CSMA Carrier sense Multiple access CSMA/CD Carrier sense Multiple access Collision detect CSMA/CA Carrier sense Multiple access Collision avoidance

4. ALOHA Network

5. ALOHA protocol

6. Collision in CSMA

7. Collision Cisco: CCNA

8. Persistent strategy

9. CSMA/CD

10. CSMA/CD animation

11. CSMA/CD CRS collision CRS defer XYZ Modified from Lucent Slide

12. CSMA/CA

13. DCF - CSMA/CA defer CRS defer CRS defer XYZ Modified from Lucent Slide

14. Multiple access protocols

15. Reservation access method

16. Poll – Select

17. Token passing

18. Token passing procedure

19. Token Ring animation

20. Multiple access protocols

21. Channelization Cellular Access Technologies Frequency Division Multiple Access (FDMA) Time Division Multiple Access (TDMA) Code Division Multiple Access (CDMA)

22. FDMA Mainly used in Analog System Bandwidth is divided into channels Voice channel  uniform BW range Not efficiency

23. TDMA Bandwidth is just one channel that is timeshared 30 KHz wide, 7.6 ms long (3 time slots) 3 times capacity over Analog Operate in 800 MHz (IS- 54) & 1900 MHz (IS-136)

24. GSM Global System for Mobile communications TDMA Use encryption  security 900 MHz & 1800 MHz (Asia-Europe) 1900 MHz (US. – not compat. with above) International support  by changing Subscriber Identification Module (SIM) card

25. CDMA One channel carries all transmissions simultaneously Spread spectrum Data  spread out Each call  unique sequence code Need accurate time stamp 800 MHz and 1900 MHz 8-10 times over Analog

26. CDMA Chip sequence Encoding rules

27. CDMA Multiplexer

28. CDMA Demultiplexer