CO-FBMC/OQAM系统导频辅助的时域相位噪声补偿

Pilot-Based Time-Domain Phase Noise Compensation in CO-FBMC/OQAM System

针对相干光偏移正交调幅技术的多载波滤波器组传输(CO-FBMC/OQAM)系统,提出一种基于导频的时域相位噪声补偿算法。建立一个时域相位噪声补偿模型,即相位噪声用时域扩展的离散余弦变换(DCT)近似,相位噪声包括公共相位误差(CPE)和非CPE相位噪声,它们均可通过估计DCT系数来获得。为了计算这些DCT系数,先用基于导频的扩展卡尔曼滤波(EKF)估计CPE,然后将CPE补偿后一部分判决错误概率较高的数据舍弃,仅保留余下的CPE补偿后数据进行预判决用以预估发送端数据,最后在波特率为32 GBaud的背对背CO-FBMC/OQAM系统中对所提算法进行仿真验证。结果表明,对比一种改进的盲相位搜索(M-BPS)算法,所提算法仅有0.5%~2.0%的频谱效率下降。针对64阶QAM、子载波数M=256或512的系统,所提算法的线宽延迟乘积容忍度仍远大于M-BPS算法,但其复杂度仅为M-BPS算法的1/2。

Aiming at the multi-carrier filter bank transmission system for coherent optical offset quadrature amplitude modulation(CO-FBMC/OQAM)technique,a pilot-based time-domain phase noise compensation algorithm is proposed.A time-domain phase noise compensation model is established,that is,phase noise is approximated by time-domain extended discrete cosine transform(DCT).Phase noise includes common phase error(CPE)and non-CPE phase noise,which can be obtained by estimating DCT coefficients.In order to calculate these DCT coefficients,the CPE is estimated by pilot-based extended Kalman filter(EKF).Then,some of the data with high error probability after CPE compensation are discarded,and only the remaining CPE compensation data are retained for pre-decision to predict the sender data.Finally,the proposed algorithm is simulated and verified in a back-to-back CO-FBMC/OQAM system with a baud rate of 32 GBaud.The results show that compared with an improved phase search(M-BPS)algorithm,the spectral efficiency of the proposed algorithm decreases by 0.5%--2.0%.For 64-order QAM systems with subcarriers M=256 or 512,the linewidth delay product tolerance of the proposed algorithm is still much larger than that of the M-BPS algorithm,but its complexity is only half that of the M-BPS algorithm.