Energy-efficient OFDM bandwidth selection for underwater acoustic carrier aggregation systems

The energy efficiency of underwater acoustic carrier aggregation in Orthogonal Frequency Division Multiplexing (OFDM) systems is studied and an energy-efficient aggregation bandwidth selection method is proposed. Via simulations it is found that (i) the aggregation bandwidth has an optimal value maximizing the energy efficiency, (ii) this optimal aggregation bandwidth decreases with increasing distance, and (iii) the energy efficiency at this optimal bandwidth drops significantly for distances above 5 km. Based on these results, an energy-efficient aggregation bandwidth selection method is proposed for an underwater system composed of a surface buoy and Autonomous Underwater Vehicles (AUVs). The proposed method is expected to optimize the transmission energy utilization by feeding back the optimal bandwidth value from the receiver to the transmitter for different distance settings. To validate the results under varying acoustic channel conditions, field experiments on the LOON testbed hosted at the NATO STO Centre for Maritime Research and Experimentation (CMRE) are currently ongoing.