Comparison of adaptive algorithms for multichannel adaptive equalizers. Application to underwater acoustic communications

Underwater acoustic digital communications are difficult because of the fading multipath nature of the channel. Adaptive equalization is known to highly improve the communication data rate by mitigating intersymbol interference (ISI). Multichannel equalizers are known to further improve the communication by a proper combination of the signals received on a sparse array. The major issue is to select an efficient receiver configuration. There are several parameters that may affect the quality of communication. In this paper, we focus on the main features that influence the performance of adaptive multichannel equalizers, such as the number and positioning of hydrophones, the length of the equalizer, the adaptive algorithm used to update the equalizer´s tap gains. The relationship between the multipath structure of the channel and the multichannel receiver´s performance is exhibited. Our analysis is performed on real data recorded on two different sea trials