A Survey of Cooperative MAC Protocols for Mobile Communication Networks

Cooperative communication is a promising and practical technique for realizing spatial diversity through a virtual antenna array formed by multiple antennas of different nodes. There has been a growing interest in designing and evaluating efficient cooperative medium access control (MAC) protocols in recent years. With the objective of translating a cooperative diversity gain at the physical layer to cooperative advantages at the MAC layer, an efficient cooperative MAC protocol should be able to accurately identify a beneficial cooperation opportunity, efficiently select the best relay(s), and coordinate the cooperative transmission with reasonable cost and complexity. However, due to the randomness of channel dynamics, node mobility, and link interference, the design of an efficient cooperative MAC protocol is of great challenge, especially in a wireless multi-hop mobile network. In this article, we aim to provide a comprehensive overview of the existing cooperative MAC protocols according to their specific network scenarios and associated research problems. Three critical issues (i.e., when to cooperate, whom to cooperate with, and how to cooperate) are discussed in details, which should be addressed in designing an efficient cooperative MAC protocol. Open research issues are identified for further research.