A two-phase broadcast scheme for underwater acoustic networks

Reliable broadcast is a critical service for Underwater Acoustic Networks (UANs). In this paper, we propose a Two-phase Broadcast Scheme (TBS) for UANs. TBS includes two phases: Fast Spreading phase and Data Recovery phase. It does not require topology or neighbor information. In the Fast Spreading phase, which is a best effort phase, opportunistic overhearing and network coding are combined to accumulate encoded packets. A probability based forwarder selection scheme is employed to alleviate the broadcast storm problem. A rebroadcast scheduling algorithm is also proposed to reduce collisions. The Data Recovery phase is to guarantee reliability if a node fails to complete data decoding in the Fast Spreading phase. Through delayed request sending, the Data Recovery phase at a node will not interfere with the Fast Spreading phase at other nodes. Through simulations, we demonstrate the advantages of TBS in terms of efficiency and reliability.