Multiuser acoustic communications with mobile users

A multiuser receiver is developed that is capable of separating receptions from independent, mobile users whose transmissions overlap in both time and frequency. With respect to any one user's Doppler corrected signal, the other communication signals appear as multiple-access interference distributed across the Doppler dimension. A previously developed receiver composed of an adaptive time-reversal processor embedded within a successive interference cancellation framework is limited to stationary users. This paper extends the receiver to properly remove the interference from moving sources by modeling the effects of Doppler through the interference cancellation receiver. The combined receiver has the ability to remove interference in both the temporal and spatial domains, and this property is shown to be preserved even when users are in motion. When applied to data collected during a recent shallow water experiment (KAM11), the receiver is shown to be capable of separating packets in a two user system where one user is moving while the other is stationary. (C) 2013 Acoustical Society of America. [http://dx.doi.org/10.1121/1.4773267]