Burst mode cooperative mac Protocol in ad hoc wireless networks

Abstract

Cooperative medium access control (MAC) protocols make use of the multi-rate capabilities of IEEE 802.11 to achieve higher throughput and shorter delay. This is achieved through transmitting a packet via a helper node by means of a faster two-hop links rather than a slower direct one-hop link. The cooperative MAC protocol transmits only one packet from the source node for each successful transmission attempt in the channel. In this paper, we extend this cooperative MAC protocol such that it is capable of transmitting multiple packets for each successful transmission attempt in the channel in an ad hoc wireless network. Furthermore, two traffic classes are considered. We call this new proposed MAC protocol as burst mode cooperative MAC. The key idea here is to maximize the successful channel access by transmitting a number of data packets instead of just one data packet as long as the overall data transmission time of multiple packets for the two-hop links is shorter or equal to the slower one-hop data transmission time of multiple packets. This cuts down the channel contention time for transmitting each packet and improves the header-to-payload overheads. Performance metrics like throughput and delay are considered. These performance metrics are evaluated via simulation. Numerical results show that the throughput of the proposed burst mode cooperative MAC can be up to 20% better than that of cooperative MAC, while the delay is still better than IEEE 802.11b MAC.