Link-Utility-Based Cooperative MAC Protocol for Wireless Multi-Hop Networks

In this paper, we propose a novel link-utility-based cooperative MAC (LC-MAC) protocol for wireless multi-hop networks. By fully utilizing the broadcast nature of wireless multi-hop networks, the node that has overheard data packets in the previous hop may become a partner of the transmitter in the current hop. As diversity gain can be achieved by virtual antenna array formed by transmitter and partner, one-phase cooperative transmission is introduced to improve the throughput. In LC-MAC, based on the instantaneous channel measurements, each node tries to maximize its own link-utility (indicator of a node's ability to cooperate) by jointly adjusting transmission rate and power. Subsequently, distributed backoff procedure is activated to select the best node that has the maximum link-utility. The optimal transmission type, rate and power are uniquely determined by the best node. Since only local information is required, LC-MAC is a completely distributed protocol. Finally, extensive simulations are performed to investigate the impact of scenario and protocol parameters on the performance of LC-MAC. Numerical results show that LC-MAC significantly outperforms the cooperative relay-based rate adaptation (CRBAR) scheme and the receiver-based rate adaptation (RBAR) scheme in terms of throughput and energy efficiency.