STUDY OF COOPERATIVE MAC PROTOCOL FOR IEEE 802.11 b NETWORKS

Abstract

Diversity is a common technique to overcome the detrimental effects of multipath fading in wireless networks at the physical layer. Diversity can be incorporated into the data link layer of wireless links in the form of Cooperative Communication. Due to the broadcast nature of wireless signals, a wireless transmission intended for a particular destination station can be overheard by other neighboring stations. A focus of recent research activities in Cooperative Communications is to achieve spatial diversity gains by requiring these neighboring stations to retransmit the overheard information to the final destination. In this dissertation work, we propose a cooperative MAC protocol, MCoopMAC, to improve the performance of the IEEE 802.1 lb medium access control (MAC) protocol. This MAC protocol leverages the multi-rate capability of IEEE 802.1 lb and allows the mobile stations (STA) far away from the access point (AP) to transmit at a higher rate by using an intermediate station as a relay. The CoopMAC I, CoopMAC II and CoopMAC+ protocols proposed in the literature improve the performance of the network by providing cooperation. The proposed protocol combines the features of CoopMAC II and CoopMAC+ for further improvement by reducing overheads. We also extend the CoopMAC II protocol for three-hop case. Simulation results show the proposed cooperative MAC protocol shows throughput improvement of the network over CoopMAC I and CoopMAC II. Performance improvement of CoopMAC II protocol is observed in the two helper case over the single helper case via simulation