Abstract:Abstract 【Objective】To address the limited coverage and low ranging accuracy of underwater visible light links caused by the strong directivity of the beam and the limited receiving angle of a single reflector/detector, this paper proposes an underwater wireless optical Integrated sensing and communications scheme based on asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) technology.【Methods】At the receiving end, At the receiving end, a sensor array consisting of corner-cube retroreflectors (CCRs) and photoelectric detectors (PDs) is constructed., with 1×CCR+1×PD as the basic sensing unit. ACO-OFDM is used as the communication-sensing fusion waveform. Active sensing uses cross-correlation calculations between the CCR echo signal and the transmitted signal to detect peak delay and obtain two-way time delay. Passive sensing uses Monte Carlo to obtain the impulse response of the underwater delay spread channel and estimate the one-way delay based on the earliest arrival time of the photon. Comparative simulations were conducted with different numbers of units and different edge unit tilt angles to evaluate BER and ranging error.【Results】In a 5 m range scenario, the root mean square error of active ranging was reduced from 8.05 cm for a single CCR structure to a minimum of 7.4 cm using an array with tilted elements, with the tilt angles ranging from 20° to 30°. The range error obtained from passive ranging was 7.46 cm. In an underwater turbulent-free channel environment, the system bit error rate can reach the order of 10?? when the signal-to-noise ratio is approximately 5.4 dB.【Conclusion】These results demonstrate that using an array configuration with an appropriate tilt angle can expand the equivalent field of view, significantly improving ranging accuracy and coverage without sacrificing communication performance.
