Hybrid-ARQ Protocol Design with Optimal Time and Power Allocation
Kaiying Sun, Weifeng Su, John D. Matyjas, Michael J. Medley · 2017
In this paper, an optimal power and time assignment strategy is developed for hybrid automatic-repeat-request (H-ARQ) communication protocol over quasi-static Rayleigh fading channels. For any given average total time duration and energy budget, we try to find the sequences of power values and time durations for H-ARQ retransmission rounds that minimize the outage probability of the H-ARQ protocol. We solve the joint optimization of power and time assignment for the H-ARQ protocol and derive a set of equations that describe the optimal transmission power and time duration sequence which enable a recursive calculation. Numerical results show that the performance of the proposed optimal-time and optimal-power assignment scheme is substantially better than that of the conventional equal-time and equal-power scheme as well as the equal-time and optimal-power scheme. For example, when the maximum transmission number is L=2 and the target data amount per packet is D_0=2000 bits, the optimal-time and optimal-power assignment scheme saves about 28dB in terms of the average energy consumption.