Transmit beamforming with beam optimization and peak-to-average power ratio reduction for mobile underwater sensor...

Transmit beamforming with arrays deployed at buoy gateway nodes can effectively improve the signal-to-noise ratio at mobile nodes in underwater acoustic networks. However, optimal beamforming matrices conventionally require accurate channel state information feedback from the mobile node, which is difficult to obtain in underwater acoustic systems because of time-varying channels, long feedback delays, and node mobility. This paper proposes a transmit beamforming method for underwater acoustic mobile networks that jointly suppresses the sidelobes to mitigate multipath interference and reduces the peak-to-average power ratio. Simulation results demonstrate that the proposed method generates better beampatterns at desired angles and achieves lower bit error rates than traditional methods, while remaining insensitive to mobile node movement. The near-real-time field experiment in the Songhua River further demonstrates its robustness for underwater acoustic mobile networks.