RC-MAC: Reduced Collision MAC for Bandwidth Optimization in Wireless Local Area Networks

The IEEE 802.11 standard for wireless local area networks (WLANs) employs a mechanism for medium access control (MAC), named distributed coordination function (DCF), which is based on carrier sense multiple access with collision avoidance (CSMA/CA). The collision avoidance mechanism uses the random backoff prior to each frame transmission attempt. The random nature of the backoff reduces the collision probability, but cannot eliminate completely these collisions. It is well known that as the number of contending stations increases, the number of collisions is also likely to increase and the performance of the 802.11 WLAN is significantly compromised. In this paper, we propose a novel distributed MAC protocol, named reduced collision MAC (RC-MAC). In our algorithm, a station access the channel by following a cyclic method. After a certain period of contention resolution, the stations simply organized in a cycle and each of them will access the channel while its turn comes. In this case, there is no more collision in the future and the bandwidth is used efficiently. Through extensive simulations, we show that RC-MAC achieves a significant increase in the overall performance compared to the standard 802.11 DCF.