A hybrid MAC protocol in data-collection-oriented underwater acoustic sensor networks

Abstract

Due to the specific characteristics in terms of long propagation delay, high bit-error-rate and limited available bandwidth in the underwater environment, designing the medium access control (MAC) protocol in underwater acoustic sensor networks (UWASNs) is a challenging issue. Considering a UWASN for data collection, data generated at sensor nodes are transmitted to the sink node hop by hop. Since the traffic load in each hop is different, single-mode MAC protocol cannot satisfy the requirement of the data collection mission. In this paper, we propose a hybrid MAC protocol for two-tier data-collection-oriented UWASN. In the proposed hybrid MAC protocol, a contention-based MAC protocol is performed in the lightly loaded sub-network, and a reservation-based MAC protocol is carried out in the heavily loaded sub-network. Moreover, the proposed MAC protocol supports the access of mobile nodes, such as autonomous underwater vehicle (AUV). Simulation results show that the proposed hybrid MAC protocol achieves high throughput.