DMT Optimal On-Demand Relaying for Mesh Networks

This paper presents a new cooperative MAC (medium access control) protocol called BRIAF (best relay based incremental amplify-and-forward). The proposed protocol presents two features: on-demand relaying and selection of the best relay terminal. "On-demand relaying" means that a cooperative transmission is implemented between a source terminal and a destination terminal only when the destination terminal fails in decoding the data transmitted by the source terminal. This feature maximizes the spatial multiplexing gain r of the transmission. "Selection of the best relay terminal" means that a selection of the best relay among a set of (m-1) relay candidates is implemented when a cooperative transmission is needed. This feature maximizes the diversity order d(r) of the transmission. Hence, an optimal DMT (diversity multiplexing tradeoff) curve is achieved with a diversity order d(r) m(1-r) for 0 ¿ r ¿ 1.