천해역 단거리 수중통신을 위한 적응등화알고리듬 성능 비교 연구

Abstract

In this paper, the performance of adaptive channel equalizer according to the adaptive algorithms and tap length of feed-forward and feed-back filters, used to cope with the inter-symbol interference due to the multipath in the received signal, is compared from the point of view of mean square error and signal constellation of the adaptive equalizer output via computer simulation, when the high-speed underwater communication system operates in the shallow water and short distance acoustic channel. Although the RLS algorithm requires much more complex operation for iterative filter coefficient adaptation, the simulation results show that the RLS algorithm is more proper than the LMS one due to the faster adaptation speed and lower MSE after converging of filter coefficients. Furthermore, the simulation results show that the length of feed-forward filter should be just longer than or equal to that of the significant part of the multipath to aggregate the multipath energy, and the length of feed-back filter should be longer enough to compensate the last arrived and relatively big multipath.