An Energy-Efficient Routing Protocol for Networks with Cooperative Transmissions

The cooperative transmissions emulate multi-antenna systems, and can be used to reduce the total energy consumption. In this paper, our objective is to quantify the advantages of using cooperative transmissions in extending the network lifetime of the energy-constrained wireless networks. We develop a detailed energy consumption model suitable for systems with cooperative transmissions taking into account the effects of channel fading. We then design a new cooperating node set selection and routing algorithm. The algorithm greedily chooses the cooperating nodes and the paths that has the minimum cost. We use a new cost metric which takes into account the transmission and reception energy costs, residual node energies, the rate of the space time block codes used, and the diversity gain provided by the cooperative transmissions. Our simulation results indicate that the network lifetime with cooperative transmissions is on the average 50% more than the lifetime with traditional transmissions. We also show that cooperative transmissions provide the maximum benefit in medium density networks and the lifetime increases when the network gets more clustered.