一种降低Flip-OFDM系统LED非线性失真的动态补偿算法  

Algorithm for reducing LED nonlinearity distortion in Flip-OFDM systems based on dynamic compensation

作　　者：陆庆峰[1] 季新生[1,2] 黄开枝[1] 

机构地区：[1]国家数字交换系统工程技术研究中心,郑州450002 [2]东南大学移动通信国家重点实验室,南京210096

出　　处：《计算机应用研究》2014年第11期3417-3421,共5页Application Research of Computers

基　　金：国家"863"计划资助项目(2013AA013603);东南大学移动通信国家重点实验室开放研究基金资助课题(2013D09)

摘　　要：针对可见光通信系统中翻转正交频分复用(Flip-OFDM)信号峰均较高导致LED非线性失真严重的问题,根据Flip-OFDM信号的单极性提出一种基于动态补偿的LED非线性失真抑制算法。首先通过最小化FlipOFDM负信号幅值确定部分传输序列(PTS)的加权系数,并对Flip-OFDM信号进行限幅(clipping),保证信号处于LED的准线性安全工作区域;然后根据正信号序列动态计算补偿信号,并承载到负信号对应的零信号位;最后接收端采用最大似然和门限判决联合检测方法,根据接收到的补偿信号恢复正信号,以降低限幅噪声。性能分析和仿真结果表明,与PTS-Clipping算法相比,动态补偿算法抑制峰均比和限幅噪声的性能更优,在误比特率为10-3处信噪比最多可有约5 dB的改进,可有效降低LED非线性失真,提高系统性能。To handle the LED nonlinearity distortion caused by the high PAPR of Flip-OFDM in visible light communication systems,this paper proposed a dynamic compensation based algorithm to reduce the LED nonlinearity distortion since the Flip-OFDM signal was unipolar.Firstly,the algorithm selected partial transmit sequence coefficient by minimizing the negative sig-nal amplitude of Flip-OFDM,and clipped the Flip-OFDM signal to ensure that the signal was in the quasi-linear operate region of LED.Then,it calculated the compensatory signal according to the positive signal sequence dynamically,and added to the corresponding zero position of negative signal sequence.Finally,it recovered positive signals according to compensatory signals in receiving terminal by combined detection methods of maximum likelihood and decision threshold algorithms,which could re-duce the clipping noise.Performance analysis and simulation results show that compared with PTS-Clipping algorithm,the pro-posed algorithm can significantly restrain PAPR and clipping noise,and have up to about 5 dB improvement for SNR where the BER is in the order of 1 0 -3 ,effectively reduce LED nonlinearity distortion to improve OFDM systems performance.

关 键 词：可见光通信 翻转正交频分复用 LED非线性失真 动态补偿 

分 类 号：TN929.1[电子电信—通信与信息系统] TP301.6[电子电信—信息与通信工程]