A Multiuser Detection Perspective on Medium Access Control in Ad Hoc Networks

Conventional medium access control protocols are designed to avoid simultaneous transmissions, based on a simple collision model in the underlying physical layer. Recently, strong physical layer capabilities enabled by multiuser detection techniques have been studied in connection with simple medium access control protocols. We think that neither of these extreme approaches is optimum, in particular for general scenarios where network nodes with different signal processing capabilities coexist. Instead of dealing with interferences in either of the two layers alone, both medium access control and physical layer functionalities should cooperate and complement each other. We discuss several key aspects for designing such a new type of protocol, especially with an emphasis on iterative multiuser detection, which can provide a good tradeoff between performance and complexity. We propose a new protocol which satisfies these key aspects. We analyze its throughput bound and also perform numerical simulations. The results evidence excellent throughput improvements.