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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。
The narrow modulation bandwidth of white light emitting diodes (LEDs) limits the system capacity of visible light communication (VLC). Non-orthogonal multiple access (NOMA) technology can increase system communication capacity through power multiplexing. Combining with DCO-OFDM and NOMA technology, the NOMA-DCO-OFDM system is designed. Based on the recursive method, a method of modeling the VLC multipath channel is given. When considering the impact of clipping noise, the SINR of the user is deduced. Fractional power distribution, gain-ratio power allocation and static power allocation are used to study the variation of system average and rate with the half-power angle of LED, FOV and power distribution factor of photodetector. The simulation results show that the system average and the rate vary with the half-power angle, the FOV and the power distribution factor, and the system average and the rate maximization can be achieved by optimizing the half-power angle, the FOV and the power allocation factor.