UW-HARQ: An underwater hybrid ARQ scheme: Design, implementation and initial test

In this paper, we investigate reliable end-to-end data transfer in Underwater Acoustic Networks. A hybrid ARQ scheme, named UW-HARQ is proposed, which combines FEC coding and ARQ. For the FEC coding, Random Binary Linear Coding is employed due to its low coding and decoding complexity. An adaptive coding ratio estimation scheme, which incorporates the PER information, is proposed to minimize the number of retransmissions between the source and the destination. For the ARQ, NACK packets are utilized to inform the source node how many and which packets to send out in a retransmission and ACK packets are used as indications of data packet recovery success. We implemented UW-HARQ on real UAN nodes by leveraging our hardware and software platform. Initial lab test results show that UW-HARQ achieves a larger throughput than TCP-like approaches with a comparable overhead.