Abstract: Repeat request (ARQ) scheme is used to retransmit the data packets after unsuccessful transmission. However, this scheme may not be effective under a deep fading channel with correlated errors. Cooperative communications, which is the important technology in next wireless communications, can improve the reliability of wireless links, which can solve the problem above effectively. The paper proposes an adaptive cooperative MAC with priority for Ad Hoc networks. The protocol can dynamically select the relay which has better channel condition based on the instantaneous channel condition, and a high priority is given to the relay. Moreover, the protocol adds the new handshake scheme based on RTS/CTS to the protocol，which further improve the system performance. In addition, the proposed protocol is modeled by a modified Markov chain, in which considers the cooperative communications and the collision resulted from the relays. Furthermore, the throughput performance is evaluated by the model. The simulation results show the proposed protocol can highly improve the system performance compared with IEEE 802.11 DCF and general cooperative ARQ protocol.
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