Cross-layer design of energy-constrained networks using cooperative MIMO techniques

We consider networks where energy is a limited resource so that energy consumption must be minimized while satisfying given throughput requirements. For such networks, cross-layer design coupled with node cooperation 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/or reception. In our scheme, local information exchange within the cluster is not necessary if Alamouti codes are used with appropriate transmission scheduling. A crosslayer design framework is then applied that optimizes routing to minimize the energy consumption and delay. For the cooperative MIMO scheme, routing is optimized based on an equivalent single-input single-out (SISO) system, where each cooperating cluster is treated as a super node. We derive the best energydelay tradeoff curve under this optimization model and show that the cooperative MIMO approach dramatically improves energy and delay performance, especially when link layer adaptation is used.