UWA massive MIMO communications

Underwater acoustic (UWA) channels are characterized by low availability of bandwidth, large propagation delays and fast varying multipaths. The fast variation of multipaths, in particular, hampers the bandwidth efficiency of UWA channels, as a significant percentage of transmission resources should be allocated to pilots. The problem magnifies further in the case of multiple-input multiple-output (MIMO) channels as the number of pilots increases linearly with the number of transmitting transducers. This paper introduces the concept of massive MIMO (a technology that has recently been proposed as a candidate for 5G wireless communication systems) for UWA channels and shows that the choice of filter bank multicarrier (FBMC) modulation for transmission in a multicarrier system removes the need for pilots, hence achieves a high level of bandwidth efficiency.