基于非正交多址的室内可见光通信系统性能优化方法

室内可见光通信(Visible Light Communication, VLC)系统常用的非对称限幅光OFDM(Asymmetrically Clipped Optical Orthogonal Frequency Division Multiplexing, ACO-OFDM)与直流偏置光OFDM(DC-biased Optical OFDM, DCO-OFDM)采用加循环前缀、信道均衡和载波复用等方法解决信道干扰及多用户复用问题，但均以牺牲有效性为代价。非正交多址(Non-orthogonal Multiple Access, NOMA)通过功率域复用提高频谱利用率，利用串行干扰消除(Successive Interference Cancelling, SIC)进行多用户信号处理，有效兼顾可靠性与有效性。将NOMA应用于室内可见光系统，建立基于NOMA-DCO-OFDM的可见光信号传输及信道增益模型。通过功率域多用户信道差异计算信道增益，进行功率分配实现功率域复用，提高系统容量和通信速率；利用SIC按功率分配算法对用户逐一解调，减弱信道干扰，提高可靠性。通过理论分析和仿真实验验证表明:该系统的通信速率达到6.8×107 bit·s?1，且合速率受用户数量的影响不显著。2用户下，误码率(Bit Error Rate, BER)为10?4时用户1有5.2 dB左右的性能提升，用户2有2.3 dB左右的性能提升，通信可靠性也明显提高。

Performance optimization method of indoor visible light communication system based on non-orthogonal multiple access

Indoor visible light communication (VLC) systems are usually designed based on asymmetric clipped optical orthogonal frequency division multiplexing (ACO-OFDM) and DC biased optical OFDM (DCO-OFDM). These system models usually use CP, channel equalization and carrier multiplexing to solve the problems of channel interference and multi-user multiplexing. But these are at the expense of effectiveness. Non-orthogonal multiple access (NOMA) improves spectrum utilization by sub-carrier multiplexing in power domain, and uses serial interference cancellation (SIC) for multi-user signal processing. It is an effective method to balance communication reliability and effectivity. An indoor VLC system based on NOMA was proposed, and a VLC signal transmission and channel gain model based on NOMA-DCO-OFDM were established. According to channel gain of multi-user, the power allocation of NOMA was carried out to realize the multiplexing in power domain and improve the capacity of system and the communication rate. SIC was used to demodulate the multi-user signals one by one according to the power allocation algorithm to reduce channel interference and improve the reliability of the system. Theoretical analysis and experimental verification show that the communication rate of the system reaches 6.8×107 bit·s?1, the combined rate is not significantly affected by the number of users, and the communication efficiency is significantly improved. For 2 users, when BER is 10?4, user 1 has about 5.2 dB performance improvement, user 2 has about 2.3 dB performance improvement, the communication reliability is also improved.