| Recently, underwater wireless sensor network (UWSN) has attracted widespreadattention because of the application in marine resources exploring, marinegeographical information gathering, monitoring and disaster prevention as well as theprotection of national security. The underwater acoustic channel is featured with longlatency, low bandwidth and highly dynamic in underwater environment, which makesexisting technologies and protocols in terrestrial wireless sensor networks (WSN)cannot be directly applied to UWSN.This paper studies underwater MAC protocol and localization technologies forUWSN. The typical MAC protocols for UWSN are presented, and MAC protocolbased on CSMA, CDMA and ALOHA will be elaborated. Furthermore, the existinglocalization algorithms are divided into two categories: the centralized and distributedlocalization algorithms, and each algorithm will be described.To solve the spatial fairness problem due to the special property of theunderwater acoustic channel and the triple hidden terminal problem caused by thelong propagation delay in underwater wireless sensor networks, and to achieve themulti-channel mechanism effectively, a single transceiver-based underwatermulti-channel MAC protocol is proposed, called SFM-MAC. Combined with theunderwater location information, it effectively addresses the problems above by usinga multi-channel RTS/CA/CL/CTS reservation mechanism, and does not require globaltime synchronization. A Markov chain is adopted to model the control channel and analgorithm to calculate the average channel throughput is presented. The performanceof the proposed protocol is verified by extensive simulation．... |
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