Bit-Loading for Non-Coherent MFSK Underwater Acoustic Communication Systems with Uneven Transmission Source Level

Non-coherent modulation is a prevalent technique in underwater acoustic (UWA) communications due to its robust performance and low complexity. However, the transmission source level of UWA communication systems is often uneven due to transducer characteristics, and the difficulty of matching between power amplifiers and transducers, which can influence the efficacy of non-coherent modulation. In this paper, a bit-loading and power allocation scheme is proposed for the non-coherent Mary frequency shift keying (MFSK) UWA communication systems with uneven transmission source level. The algorithm adjusts the bit and power allocation on frequency groups according to the corresponding frequency gain, with the objective of improving the spectral efficiency and reliability. Simulation results show that the proposed algorithm outperforms the traditional even bit and power allocation, with a significant improvement in the effective throughput and spectral efficiency of the system.