Energy efficiency analysis of HARQ with chase combining in multi-hop wireless sensor networks

In this paper we analyze the energy efficiency of multi-hop communication in wireless sensor networks when packet transmissions between adjacent nodes employ Hybrid ARQ (HARQ) with Chase combining (CC) technique under Rayleigh block-fading channels. The energy analysis can be constrained by either a target outage probability or end-to-end delay. Closed form expressions for the end-to-end outage probability and energy consumption are derived. Results show how to determine the optimal number of retransmissions of the HARQ-CC scheme for a given number of relays between the source and destination nodes, in order to achieve the target constraints. The impact of the path loss environment conditions on the overall energy consumption is also investigated. Finally, we analyze the energy consumption assuming a visual sensor network application with multiple cameras and different outage and delay constraints.