A Cross-Layer Protocol with High Reliability and Low Delay for Underwater Acoustic Sensor Networks

A cross-layer protocol is proposed to deal with the problems of high latency, low bandwidth and high bit-error-rate (BER) in underwater acoustic sensor networks (UASNs). Nodes are organized as clusters based on depth and the nodes with same depth belong to same cluster and cluster head (CH) is chosen by the CH in high-level depth. At network layer, nodes in different depths send packet to their CH hop by hop and CH transmits the aggregated data to the one-depth higher CH till the data arrives at sink node in surface; At MAC layer, a CSMA/CA-based MAC protocol is used in each cluster while CHs use a pre-defined schedule to allocate the channel; At physical layer, nodes change the transmission power and frequency to decrease channel collision and energy consumption in a self-adaptive way. According to the simulation results, it brings benefits in improving transmission reliability and decreasing transmission delay.