离散多音调制可见光信道非线性失真及参数优化

Nonlinear distortion and parameter optimization of visible light communication channel based on discrete multi-tone modulation

为了改善离散多音调制（DMT）点对点可见光通 信（VLC）性能,首先给出了 DMT技术原理并建立了实验装置,进而研究了16-相位键控（16-PSK）DMT信号直 流偏压和探测器偏置电阻对VLC信道非线性失真的影响。为了使VLC信道工作于良好的线 性区,优化得到了不同通信距离下系统的最佳直流偏压和探测器偏置电阻。在VLC信道响 应存在非线性失真和调节系统参数使其工作于线性区两种情况下,在0.2Mbit/s数据传输速 率下分别开展了通信实验,并测试了系统在不同通信距离处的误码率（BER ）。结果显示,BER可 由未做参数优化时的10^－1量级降至10^－3量级；且在20-90cm通信距离范围内 BER几乎恒 定,表明系统稳定性也得到了明显改善。本文的实验测试和分析结果为进一步优化系统参数 及改进通信性能提供了数据依据。

In order to improve the communication performance of point-to-point visible light communication （VLC） system with discrete multi-tone （DMT） modulation,the DMT communication technique and the hardware system are proposed,and the effects of direct current bias of 16-phase-shift-keying （16-PSK） DMT signal and the det ector′s bias resistance on the nonlinear distortion of VLC channel response are investigated. For enabling the VLC channel working at a proper linear region,the best direct curr ent bias of the DMT signal and the best detector′s bias resistance are derived under different communication distances.Under the cases of VLC channel working at nonlinear region and linear region,a series of experiments are carried out under a bit rate of 0.2Mbit/s,and the bi t error rates （BERs） are measured under different communication distances.The results s how that the BER can be decreased from the level of 10^-1 without parameter optimizatio n to 10^-3 with optimized DC bias and detector′s bias resistance,and the BER value is nearly constant wit hin the communication distance range of 20-90cm,suggesting an enhancement of system st ability.The experimental and analytical results in this paper provide data b asis for system parameter optimization and further improvement in communication performance.