Cross-layer optimization of sensor networks based on cooperative MIMO techniques with rate adaptation

We consider energy-constrained networks where we need to transfer information with minimum energy consumption and delay. For such networks, cross-layer design coupled with node cooperation and rate adaptation can significantly reduce both energy consumption and delay. In this paper, we propose a cooperative multiple-input multiple-output (MIMO) technique where multiple nodes within a cluster cooperate in signal transmission and reception with optimal rate. In our scheme, local information exchange within the cluster is not necessary if Alamouti codes are used with appropriate transmission scheduling. A cross-layer design framework is then applied that optimizes routing and rate to minimize the energy consumption and delay. For the cooperative MIMO scheme, routing is optimized based on an equivalent noncooperative system, where each cooperating cluster is treated as a super node. We derive the best energy-delay tradeoff curve under this optimization model and show that the cooperative MIMO approach dramatically improves energy and delay performance, especially when rate adaptation is used.