Channel aware MAC scheme based on CSMA/CA

The knowledge of channel states can improve the performance of wireless communications systems, and its benefits are outstanding where the channel states vary rapidly with time. The fast feedback of channel information was realized in the downlink of cdma2000 1/spl times/EV-DO system and it shows great enhancement in terms of total average throughput. However, it does not scale well since the burden of feedback channels increases proportionally with the increase of users in number. We propose a multiple access scheme based on CSMA/CA, which gives high priority to users in the good channel by assigning small backoff counters. Since the channel gain is used to choose the backoff counter locally, it is not sent back to the central controller, thereby achieving low overhead and complexity. Our proposed channel aware MAC scheme adapts to traffic conditions dynamically by changing the size of contention window when collision occurs.