在可见光通信(visible light communication，VLC)系统中，针对用户位置、接收机朝向对视距(line of sight，LOS)链路影响严重，以及实时准确的信道状态信息(channel state information，CSI)反馈需求而导致的整体计算复杂性问题，对用户位置和接收机朝向随机的下行VLC系统性能进行了研究，并利用非正交多址接入(non-orthogonal multiple access，NOMA)技术提高频谱利用率。根据用户位置以及接收机朝向模型建立的室内VLC系统一般框架，推导了中断概率以及遍历和速率解析表达式。在此基础上，进一步提出了不同的NOMA调度机制及用户反馈策略，以提高系统性能、降低链路开销。最后，通过蒙特卡洛仿真验证了解析结果的正确性。仿真结果表明，用户位置和接收机朝向会严重影响VLC系统性能，且对于任意NOMA调度机制，同时反馈距离和朝向信息比只反馈距离信息更具优越性。
Performance of NOMA-VLC systems with random receiver orientation
In visible light communication(VLC)systems,a pivotal challenge arises from the significant impact of user position and receiver orientation on the line of sight(LOS)links,along with the overall computational complexity caused by the necessity for real-time and precise channel state information(CSI)feedback.The performance of downlink VLC systems with random user positions and receiver orientations was investigated,and non-orthogonal multiple access(NOMA)was utilized to enhance spectral efficiency.By establishing a comprehensive framework for indoor VLC systems,taking into account models of user position and receiver orientation,analytical expressions for outage probability as well as ergodic sum rate were derived.On this basis,varied NOMA scheduling mechanisms and user feedback strategies were also introduced to improve system performance while reducing link overhead.Furthermore,the correctness of analytical expressions was validated through Monte Carlo simulations.The simulation results reveal the significant impact of user position and receiver orientation on the performance of VLC systems,and for any NOMA scheduling mechanism,the integration of both distance and orientation feedback markedly outperforms feedback only distance information.
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维普
