降低可见光OFDM系统限幅失真的部分线性压扩变换研究  

Research on Partial Linear Companding Transform for Reducing the Clipping Distortion of Visible Light OFDM System

作　　者：张俊[1] 张剑[1] 

机构地区：[1]解放军信息工程大学信息系统工程学院,河南郑州450001

出　　处：《信号处理》2016年第1期113-118,共6页Journal of Signal Processing

基　　金：国家自然科学基金(61271253);国家863计划(2013AA013603)资助项目

摘　　要：针对可见光正交频分复用(OFDM)系统发光二极管(LED)限幅失真严重的问题,提出一种部分线性压扩变换方法。输出光功率约束较大或较小时,在发射端对直流光正交频分复用(DCO-OFDM)双极性信号中的正信号或负信号进行线性压缩变换,在接收端对压扩信号进行扩展变换可以有效地减小限幅噪声。输入信号功率一定时,在有效信噪比最大原则下对部分线性压扩变换系数和直流偏置进行优化,系统能够获得最佳性能。仿真实验表明,随着约束光功率增大,系统性能越差,且压缩系数的最优值也越小。随着QAM调制阶数的增加,部分线性压扩变换获得的性能增益越小。To handle the significant clipping distortion of light emitting diode （LED） in visible light orthogonal frequency division multiplexing （OFDM） system, a method of partial linear companding transform is proposed. Under the higher or lower optical power constraints, the positive or negative signal of bipolar direct current optical orthogonal frequency division multiplexing （DCO-OFDM） signal is linearly compressed at the transmitter and the companded signal is linearly expanded at the receiver. It can effectively reduce the clipping noise. With a certain input signal power, the best system performance is achieved by optimizing the coefficient of partial linear companding transform and the DC bias based on the principle of maximum effective signal to noise ratio （SNR）. Simulations show that the system performance becomes worse with the in- crease of optical power constraint. Also the optimal value of the compressing coefficient becomes smaller. With the increase of QAM modulation order, the system performance gain obtained by partial linear companding transform becomes smaller.

关 键 词：限幅失真 部分线性压扩变换 光功率 双极性信号 有效信噪比 

分 类 号：TN911.7[电子电信—通信与信息系统]