Cooperative ARQ-Based Energy-Efficient Routing in Multihop Wireless Networks

In this paper, we design an integrated protocol that jointly optimizes the performance of the physical, medium access control (MAC), and network layers. Our goal is to minimize total network energy consumption while delivering a minimum required signal-to-noise ratio (SNR) at each intended receiver within the network. At the MAC layer, we develop a cooperative automatic repeat request (ARQ) system, in which the relay nodes assist the source with its retransmission attempts. A complete analytic framework for the cooperative system is developed. Using this framework, we find the optimum transmission energy at the physical layer. To demonstrate the effectiveness of the proposed scheme in minimizing energy consumption, we propose two cooperative routing algorithms at the network layer. The proposed algorithms utilize the derived cooperative link cost as a basic building block. Through analysis and simulations, it is shown that over a single hop, cooperative transmission can achieve energy savings of up to 73%, as compared with noncooperative transmis.sion. The simulation results also demonstrate that the proposed routing algorithms can achieve significant energy savings while using fewer hops, as compared with the baseline cooperative and noncooperative routing algorithms.