Adaptive frequency hopping underwater acoustic communication system based on channel quality factor

Abstract

Due to the adverse time-space-frequency selective fading characteristics of underwater acoustic channel, it is difficult to balance the high speed and the robustness of underwater information transmission from the perspective of long-term marine environmental monitoring. An adaptive frequency hopping (FH) underwater acoustic communication (UAC) scheme based on channel quality factor is proposed in this paper. In this scheme, the channel quality factor (CQF) is defined as the weighted sum of signal-to-noise ratio (SNR) and multipath spread to quantitatively evaluate the channel quality. By setting two type of FH modes, i.e., high data rate mode and high reliability mode, the channel quality factor is calculated through the signal demodulation process to facilitate adjustment of frequency hopping mode switching. Field trial performed in Wuyuan bay show that the proposed adaptive FH UAC scheme can adapt to the time variations of shallow water channel, by selecting the appropriate communication mode to match the channel, and achieving a balance between the communication efficiency and reliability.