Performance analysis of a JSW-based MAC protocol for mobile underwater acoustic networks

The design of the media access control (MAC) protocols for mobile underwater acoustic networks (UANs) poses significant challenges due to the characteristics of underwater acoustic channels such as limited bandwidth, high bit error rate and long propagation delay. The reasons that existing underwater MAC protocols have shown poor performance, to a great extent, lie in the following aspects: 1) the majority of them are lack of error-control mechanisms; 2) those having error-control mechanism are largely based on the conventional stop-and-wait (SW) transmission scheme, which is not efficient. To combat the effect of these unfavorable factors, we have proposed an efficient transmission scheme, namely, the juggling-like stop-and-wait (JSW) transmission scheme, whereby the most efficient selective-repeat automatic-repeat-request (SR-ARQ) protocol can be directly applied in underwater data transmissions. In this paper, we propose a JSW-based MAC protocol for UANs (called UJ-MAC) by making use of the multi-channel technique. Specifically, of all the channels, one is used as the control channel (CCH) while the others are used as data channels (DCH); upon completion of handshaking on CCH, nodes transmit data in the JSW manner on DCH. We then develop an analytic model, deriving a closed-form expression of the throughput of UJ-MAC. Numerical results show its superior throughput performance as compared to its counterparts, particularly under the heavy traffic situations.