A Low-PAPR Underwater Acoustic Multiuser Communication Algorithm Based on Selective Differential Coding and SC-FDMA

Underwater acoustic communication transmission consumes relatively high power, so the system needs to have a lower Peak-to-Average Power Ratio (PAPR). In this paper, a low-PAPR underwater acoustic multiuser communication algorithm based on Selective Differential Coding and Single-carrier Frequency Division Multiple Access (SLD-SC-FDMA) was proposed in allusion to the PAPR problem in underwater acoustic Orthogonal Frequency Division Multiplexing (OFDM) system. At the transmitting end, the signal is differentially coded into a baseband symbol by multiple sets of initial phases; Discrete Fourier Transform is performed for the target user's frequency band, and the information of each baseband symbol is distributed to all frequency bands of the user, then the sum of information on all frequencies at each moment is a baseband symbol; the actual symbol information in the space (when the symbol is simultaneously transmitted in the full frequency domain) is calculated with Inverse Discrete Fourier Transform for all frequencies; and the group that minimizes PAPR is selected and added with a cyclic prefix before being sent out through the transducer. At the receiving end, the demodulation process opposite to the transmitting end is completed, and the original bit information is estimated. Good simulation and experimental results verified the effectiveness of the proposed algorithm.