High fidelity underwater wireless optical communication with a phase-conjugated frame structure

摘要

In this paper, the influence factors of phase noise are first analyzed in detail and verified by experiments, and its principle is theoretically derived. Besides, we propose a novel, to the best of our knowledge, frame structure for m-quadrature amplitude modulation-orthogonal frequency division multiplexing (m-QAM-OFDM) in underwater wireless optical communication. The frame structure contains OFDM signals and their phase-conjugated signals. At the receiving end, by the simple superposition of phase-conjugated symbols, the noise suppression can be achieved. The feasibility is experimentally demonstrated by transmitting m-QAM-OFDM signal in different modulation formats and scenarios. The results show that bit error rate performance can be significantly improved, and there is also a significant increase in transmission capacity compared to the traditional phase-conjugated method. Moreover, the proposed frame structure can provide a robust and simple compromise between transmission capacity and distance. (C) 2020 Optical Society of America