Performance comparison of sender-based and receiver-based scheduling MAC protocols for underwater sensor networks

Underwater Sensor Network (UWSN) is significantly different from terrestrial network in that acoustic signal is mainly used as the communication medium. The acoustic signal imposes high bit error rate, limited bandwidth and long propagation delay which, to some extent, influences the design of various services in UWSNs. MAC protocol, however, is one of the protocols which has been completely affected by the unique features of underwater environment. For UWSNs, energy-efficiency is now a major concern due to difficulties of replacing or recharging batteries. In order to save energy, most of the proposed MAC protocols follow a pattern of sleeping and listening mode, since the sleep mode energy consumption is much less than that of the idle listening mode. Hence, the energy efficiency is directly dependent upon how the sleeping and listening modes are scheduled at each node. In some protocols, sender-based scheduling, the
schedule is specified by the sending nodes, whereas in receiver-based scheduling the receiving nodes decide to schedule data transmission. In this paper, we evaluate the UWAN-MAC, as a sender-based, and R-MAC, as a receiver-based scheduling. Our simulation results show that the receiver-based always performs well in terms of energy consumption for small size networks and under light traffic. However, by increasing the number of nodes or traffic load, the sender-based highly outperforms the receiver-based scheduling protocols in terms of end-to-end delay and throughput.