Bit per Joule Achievable Rate of Cooperative Sensor Networks with Hybrid ARQ

Cooperation in wireless networks has been recently considered as a technique to increase the network throughput. However, for sensor networks with limited available energy, this benefit may come at the expense of a increased energy consumption due to the simultaneous transmission by many nodes. In this paper we consider the bit per Joule achievable rate (AR) as a performance measure of a cooperative wireless network, i.e. the bits transmitted per unit energy consumed by the entire network. For a network using carrier sense multiple access (CSMA) and hybrid automatic repeat request (HARQ) as error correction mechanism, we evaluate the bit per Joule AR for different cooperation configurations. The analysis includes the effects of path-loss and Rayleigh fading while as cooperative schemes we consider decode and forward, distributed space time coding and multiplexing coding.