Implementation and evaluation of multihop ARQ for reliable communications in underwater acoustic networks

Underwater acoustic networking is an emerging technology platform for oceanographic data collection, pollution monitoring, offshore exploration and tactical surveillance applications. Design of reliable and efficient communications protocols is challenging due to the unique characteristics of underwater acoustic channels. In this paper, we present a modular and lightweight implementation of an opportunistic multihop automatic repeat request (ARQ) scheme in a real system. We evaluate the performance of the opportunistic ARQ using inexpensive underwater acoustic modems in a shallow underwater environment.