Angle-of-arrival-based detection of underwater acoustic OFDM signals

We propose a spatial combining technique for detection of multicarrier underwater acoustic communication signals using a vertical array of receivers. Instead of estimating the channel for each receiver independently and ignoring the angles of arrival of each of the channel paths, the suggested technique is based on spatially filtering each of the channel paths by steering a multi-frequency beamformer to their angles of arrival. As the number of channel paths is usually smaller than the number of the receivers, this process reduces the dimensionality of the model and involves a lower computational load. The signals at the output of the beamformer are then decoded in a coherent or differentially-coherent form. Simulation results show that angle-of-arrival-based detection outperforms the traditional angle-of-arrival-ignorant spatial combining methods for low signal to noise ratio and moderate range.