While a large number of wireless MAC protocols have been studied, they are not suitable for Underwater Acoustic Networks (UANs) due to long propagation delay, limited band-width and high bit error rate, which pose challenges to underwater MAC protocol design.

In order to solve these problems, researchers of Institute of Acoustics, Chinese Academy of Sciences carried our a series of studies and proposed an underwater MAC protocol based on Carrier Sensing Multiple Access with Collision Avoidance (CSMA/CA), which is called UW-CSMA/CA (CSMA/CA for underwater). They investigat three areas of improvement, namely, the control rules, the deferral rules, and the backoff slot time. They conduct simulations in ns2 and the result demonstrates that the throughput performance of UW-CSMA/CA is clearly higher than that of original CSMA/CA protocol. The researchers also conclude some regulations between throughput and network parameters, which provide basis of network optimization.

This work is supported by the National High Technology Research and Development Program of China ('863' Program) and is also supported by the National Natural Science Foundation of China.