The Average Total Power Consumption of Cooperative Hybrid-ARQ on Quasi-Static Rayleigh Fading Links

In this paper, the average total power consumption per information packet is investigated for a cooperative hybrid automatic-repeat-request (H-ARQ) protocol in a quasistatic Rayleigh fading environment. Specifically, a closed-form expression of the average total transmission power is obtained for the cooperative H-ARQ relay protocol, in which the source may use different transmission power level in different (re-)transmission rounds. The closed-form expression is valid for any maximum number of (re-)transmission rounds L allowed by the protocol and may play a key role thereafter in optimizing power allocation. Since the closed-form expression is complicated for large L, an approximation of the average total transmission power is developed which is asymptotically tight at high SNR. Extensive simulation and numerical results are also provided herein to illustrate and validate the theoretical results.