CAP-DPIM可见光混合调制方案

针对可见光通信系统传输性能问题,文章提出了一种无载波幅度相位(CAP)调制与数字脉冲间隔调制(DPIM)结合的混合调制方案。该方案分别利用两者频谱效率和功率效率较高的特点,发送端在脉冲间隔调制的脉冲时隙加载直流偏置光CAP(DCO-CAP)信号,实现混合调制信号的并行生成,接收端通过门限检测和最大似然检测完成混合调制信号的串行解调。推导了室内可见光高斯信道下混合调制方案的误码率(BER)及误帧率(FER)解析表达式。此外,从频谱效率和FER两方面对比分析了该混合调制方案与传统DPIM及DCO-CAP方案的性能优劣。数值仿真结果表明:当频谱效率相同时,混合调制方案较单一调制有更高的可靠性。

A Scheme of CAP-DPIM Hybrid Mudulation for VLC

In order to improve the performance of indoor Visible Light Communication(VLC)system,a hybrid modulation scheme combining Carrierless Amplitude Phase(CAP)modulation and Digital Pulse Interval Modulation(DPIM)is proposed.This scheme takes advantage of both characteristics of higher spectral efficiency and power efficiency.A parallel modulation structure is adopted to realize the signal generation at the transmitter side,and the transmission of Direct Current biased Optical-CAP(DCO-CAP)signal are controlled by pulse time slot of the pulse interval modulation.The threshold value detection and the maximum likelihood criterion are used to complete the serial demodulation of modulated signals at the receiver side.Analytical expressions of Bit Error Rate(BER)and Frame Error Rate(FER)for the hybrid modulation scheme over Gaussian channel are derived.In addition,the performance of the proposed scheme and ordinary schemes are contrastively analyzed in terms of spectral efficiency and system reliability.The numerical results show that the hybrid system is more reliable compared with ordinary modulation system under the condition of same spectral efficiency.