Laser-based indoor mobile wireless communication aided by stabilizers

Laser-based optical wireless communication (OWC) can provide multi-Gb/s data rates for future indoor mobile wireless networks. However, due to the directionality of laser beams, the performance of indoor laser-based OWC suffers from the misalignment induced by the random orientation of user devices. To address this challenge, this work proposes the application of stabilizers at the user equipment to mitigate device orientation effects. Additionally, to support user mobility, we present a framework to optimally design receivers employing avalanche photodiode (APD) arrays, thereby providing a broad receiver field-of-view (FoV) while still upholding a wide bandwidth. Experimental measurements are conducted to assess the statistics of the random orientation angles of the user device across five practical movement types, both with and without stabilizers. Several analytical models are developed to precisely approximate the PDFs of the orientations in different scenarios, enabling performance evaluation of stabilizer-assisted OWC in the presence of misalignment. In addition, the trade-off between FoV, bandwidth, and signal-to-noise ratio (SNR) in the APD array-based receivers is analyzed. Based on this analysis, a receiver design algorithm is proposed, aimed at determining the optimal receiver configurations to maximize the achievable data rate given a desired FoV. Our simulation results, based on an indoor uplink high-speed OWC scenario, illustrate the effectiveness of the proposed system in mitigating the effects of misalignment, thereby decreasing the outage probability and enhancing the achievable data rate.