Ali Al- Saihati ID# 200350130

1. King Fahd University of Petroleum & Minerals Electrical Engineering DepartmentEE 578 Simulation of Wireless SystemsMultiple Access Protocols Assignment # 6 Ali Al-Saihati ID# 200350130

2. Outline • Introduction. • Classification of Multiple Access Protocol. • Random Access Protocols. • Packet Communication System.

3. Introduction • Multiple access protocol. • Efficient use of sources. • Multiplexers are used for users.

5. Properties • Share common transmission channel. • Perform allocation. • Fairness. • Flexibility. • Stability. • Robust. • Wireless: hidden terminal- near far effect- multipath fading- cochannel interference.

6. Classification of Multiple Access Protocol

7. Scheduling • Two types of scheduling: 1) Fixed assignment scheduling: fixed slots for each user. 2) Demand assignment scheduling: active users are only allowed to transmit. • Two approaches of demand assignment scheduling: 1) Centralized control like polling. 2) Decentralized control like token ring.

8. Contention • Two types: • 1) Repeated random: ALOHA- slotted ALOHA. • 2) Reservation: rALOHA- PRMA.

9. Random Access Protocols • ISMA: has different types. • Non-persistent. • 1-persistent. • P-persistent.

10. Packet Communication System

11. Access terminal: same for all users – has buffer (FIFO)- finite and infinite buffer. • Communication channel: wired (no errors) & wireless (propagation loss- shadowing). • Packet generation: independency- constancy- rareness. • Collision: wired( same power)- wireless ( attenuated power). • Offered traffic: G = T/R • Throughput: S = T x n/R

12. Characteristics of G, S and D

14. ALOHA • S = Ge-2G • Max: G= 0.5 , S= 0.184

16. Slotted ALOHA • S = Ge-G • Max: G= 1 , S= 0.368

18. Nonpersistence CSMA

20. Slotted Nonpersistence Slotted ISMA

22. Thank You