Energy Efficiency of Opportunistic Routing with Unreliable Links

During the last decade, many works were devoted to improving the performance of relaying techniques in ad hoc networks. One promising approach consists in allowing the relay nodes to cooperate, thus using spatial diversity to increase the capacity of the system. However, this approach introduces an overhead in terms of information exchange, increasing the complexity of the receivers. A simpler way of exploiting spatial diversity is referred to as opportunistic routing. In this scheme, a cluster of nodes still serves as relay candidates but only a single node in the cluster forwards the packet. In this paper, we put forward an analytical framework to optimize the opportunistic communication scheme in order to minimize the energy consumption. Meanwhile, the optimizations of node density and the transmission power are analyzed for different ranges of relay candidates in Rayleigh block fading and Additive White Gaussian Noise (AWGN) channels. In the energy consumption viewpoint, the analyses indicate that the opportunistic communication is more efficient in Rayleigh block fading channel than that in AWGN channel.