Energy Efficiency of Multi-Hop Underwater Acoustic Networks Using Fountain Codes

Ensuring low energy consumption is a crucial issue in underwater communications, since battery replacement may be difficult and expensive in these scenarios. We analyze in this paper the energy consumption of a multi-hop underwater acoustic network (UWAN) employing fountain codes. Moreover, in order to reduce this energy consumption we optimize the modulation order assuming differential phase-shift keying ( $M$ -DPSK), as well as the number of hops. We investigate the required number of fountain-encoded packets for different modulation orders. Our results show that, by optimizing the modulation order, the number of hops and the number of fountain packets, we can obtain important energy savings, especially for long distances. In addition, with the proposed scheme the energy consumption decreases significantly compared to the case without fountain codes, reaching up to 40% of savings.