On the predictability of underwater acoustic communications performance a case study

In this paper, we analyze the predictability of the communications performance of an adaptive modulation system for underwater acoustic communications. As a case study, we consider the KAM11 data set, which has been collected off the coast of Kauai Island during July 2011. We measure the signal to noise ratio at the output of the equalizer and we observe slow fluctuations over time intervals of up to six minutes. Based on an analytical model and using the estimated time correlation coefficient of subsequent values of the signal to noise ratio (SNR), we compute the communications performance as a function of the feedback delay for an adaptive modulation system, and we evaluate its predictability. We show that it is possible to know in advance the trend of the performance over intervals of three to four minutes.