白光发光二极管(LED)的窄调制带宽限制了可见光通信(VLC)的系统容量。非正交多址接入(NOMA)技术通过功率复用可提高系统通信容量。结合直流偏置光正交频分复用(DCO-OFDM)和NOMA技术,设计了NOMA-DCO-OFDM系统。基于递归法给出了单个LED时VLC多径信道建模方法。在考虑限幅噪声影响时,推导了用户的信干噪比。采用分数阶功率分配、增益比功率分配和静态功率分配方法,研究系统平均和速率随LED半功率角、光电检测器的视场角(FOV)和功率分配因子的变化规律。仿真结果表明,系统平均和速率随着半功率角、FOV和功率分配因子的变化而变化,可以通过优化半功率角、FOV和功率分配因子达到系统平均和速率最大化。

Achieving large system capacity is a challenge due to the narrow modulation bandwidth of the white light-emitting diode (LED) in visible light communication. The system capacity can be improved by the non-orthogonal multiple access (NOMA) technique which can reuse power. A NOMA-DCO-OFDM system which is a combination of NOMA technology and direct-current-biased optical orthogonal frequency division multiplexing (DCO-OFDM) is proposed. Furthermore, a modeling method for VLC multipath channel is proposed based on the recursive method when a single LED is used. The signal to interference and noise ratio of users is derived when the clipping noise is considered. We also study the relationship among average sum rate of system, half power semi-angles of LED, field of views (FOV) of photoelectric detector and power distribution factor with methods of fractional order power allocation, gain ratio power allocation and static power allocation. The simulation results indicate that the average sum rate of system changes with the changing of half power semi-angles of LED, field of views (FOV) of photoelectric detector and power distribution factor, and the maximum average sum rate can be achieved when we optimize the half power semi-angles, FOV and power distribution factor.