Optimizing network performance through packet fragmentation in multi-hop underwater communications

Random access protocols for multi-hop underwater wireless sensor networks that use control packets such as RTS/CTS have been shown to reduce or eliminate collisions between data packets, but they typically remain prone to collisions between control and data packets. Although control packets are usually much shorter than the data packets, when a control/data collision occurs, the entire data packet may have to be discarded. To reduce the effect of this type of collision, long data packet can be partitioned into smaller fragments confining the disruptive effect of a collision only to few fragments, so that only those need to be retransmitted. Despite the higher overhead (each fragment carries physical and the MAC headers and information on packet re-assembling), fragmentation reduces the overall traffic and the number of re-transmissions in the network. This technique is investigated in conjunction with the distance-aware collision avoidance protocol (DACAP). Simulation results show that data packet fragmentation offers benefits to throughput efficiency, end-to-end latency and energy consumption.