MULTIUSER DETECTION IN A HORIZONTAL UNDERWATER ACOUSTIC CHANNEL USINGARRAY OBSERVATIONS

We present a multisensor, multiuser receiver that is capable of operat ing in an underwater acoustic channel with severe multipath, For each active user, the receiver consists of a multi-input, single-output arr ay processing filter followed by a single-channel adaptive equalizer, The array processing biter is chosen to maximize an averaged performan ce metric which measures reduction in the interference from multiple a synchronous cochannel users and the reduction in intersymbol interfere nce caused by time spreading of the transmitted signal. The single-cha nnel adaptive? equalizer that follows the array processing filter elim inates the remaining intersymbol interference prior to hard symbol dec isions. The division of labor between the array processing filter and single-channel equalizer reduces receiver complexity by allowing the a rray processing filter weights to be based on the fixed deterministic channel component and the single-channel equalizer to be based on the stochastic channel component, Receiver performance is demonstrated usi ng data obtained from two shadow-water acoustic channels where tyro co channel users are transmitting In shallow water at IS and 30 nautical miles from the receiver array.