DOPPLER FREQUENCY ESTIMATION AND RECEIVING METHOD FOR TIME-VARYING UNDERWATER ACOUSTIC COMMUNICATION CHANNEL

摘要

The present invention presents a frame recursive modulation and demodulation method for estimating and compensating doppler frequency information even in a data section in order to enhance transmission efficiency in an underwater acoustic communications environment. The present invention performs a simulation experiment using VirTEX, which is a marine environment channel modelling program, through which the presented method shows enhanced performance rather than a conventional modulation and demodulation method, and checks that the performance is varied according to the size of a subframe. In addition, the present invention checks an error propagation phenomenon of influencing an error, generated in an initial stage of a frame, on an equalizer within a receiving device to diffuse a bit error to the latter half part. The presented method resulted from the experiment shows a non-encoded bit error rate lower than a conventional method, and checks that the non-encoded bit error rate per 100 bits, having been increased as going to the latter half part, gets reduced. The present invention checks that the presented method enhances the bit error rate by about 32% rather than the conventional method. If a channel encoding scheme is applied in the future, the error rate of recursive data gets reduced and the doppler frequency is more precisely estimated.