Performance analysis of hybrid ARQ schemes in underwater acoustic networks

The characteristics of the underwater acoustic communication, such as large propagation delay, high bit error rate and half-duplex, bring great challenges to traditional automatic repeat request (ARQ) schemes. In this paper, we propose two hybrid ARQ (HARQ) schemes, Type-I HARQ and Type-II HARQ, for the underwater acoustic system according to the specific characteristics of the underwater acoustic communication. The performance of both HARQ schemes, in terms of the throughput efficiency, the average transmission delay of a packet and the packet error rate, is analyzed and derived. Simulation results show that the performance of the HARQ schemes is better than that of the pure ARQ schemes, the wait-stop ARQ and M-ARQ, especially for the small SNR. Moreover, simulation results also reveal that the Type-I HARQ scheme has an obvious advantage in the case of moderate SNR (7~10dB), while the Type-II HARQ scheme is still contributing when the SNR is as low as 5 dB.