Distributed cooperative MAC for wireless networks based on network coding

In dense wireless local area networks (WLANs), the hidden stations (HSs) cause severe collisions and performance degradation. Although cooperative communications can achieve spatial diversity, how to efficiently cooperate in a wireless network is a challenging issue due to the distributed nature of the stations. The contributions of this paper are two-fold. First, we establish an analytical model for the IEEE 802.11 WLANs with HSs using the mean value analysis method, which can provide the theoretical results of collision probability, frame service time and network throughput. Second, we propose a new medium access control (MAC) protocol, named network coding cooperative MAC (NCC-MAC) to utilize cooperation to relieve the HS problem. Different from the traditional RTS/CTS scheme, NCC-MAC utilizes random linear coding (RLC) to realize opportunistic cooperative transmission without extra control messages. Furthermore, the ACK-triggering mechanism is introduced which can help to avoid repeated collision caused by HS(s) in dense WLANs and also improve the efficiency of the coded cooperation. Simulations have been conducted to compare the performance of NCC-MAC with DCF, simple cooperative MAC (SC-MAC) without network coding, and other cooperative MAC in the literature. The results show that NCC-MAC can effectively realize station cooperation and reduce the effect of HS(s), improving the network throughput and delay performance considerably.