模分复用系统中盲均衡算法的均衡性能研究

Research on equalization performance of blind equalization algorithms in mode-division multiplexing system

恒模算法(CMA)是一种广泛应用于模分复用系统的算法,可对系统中模式耦合、差分模式群时延和色散等损伤因素进行均衡补偿,进而得到理想信号。为了研究CMA算法在强耦合模分复用系统中的均衡性能,采用功率耦合理论搭建6×6模分复用系统模型,并在接收端使用CMA和修正的恒定模数算法(MCMA)对系统输出信号进行均衡,获得了星座图、均方根误差(RMSE)值和误比特率(BER)。结果表明,在星座图方面,MCMA可以减少散点,使星座点更紧凑;在RMSE方面,MCMA均衡后的信号的RMSE值小于CMA均衡后得到的RMSE值,说明MCMA均衡后的数据离散程度较低;在BER方面,当BER为10-3时,MCMA要求的光信噪比比CMA低1.0 dB,因此,MCMA的均衡效果优于CMA。该研究结果为强耦合模分复用系统中的均衡算法提供了一些参考。

The constant modulus algorithm(CMA)is a popular algorithm for mode-division multiplexing systems to equalize and compensate for impairments such as mode coupling,differential mode group delay,and dispersion in the system to obtain the desired signal.In order to study the equalization performance of the CMA in the strong coupling mode-division multiplexing system,the power coupling theory was used to build a 6×6 mode-division multiplexing system model and use the CMA and modified constant modulus algorithm(MCMA)at the receiving end to equalize the system output signal and obtain the constellation diagrams,root mean square error(RMSE)values and bit error rate(BER).The results show that in terms of the constellation diagram,MCMA can reduce scatter points and make constellation points more compact;in terms of RMSE,the RMSE value of the signal after MCMA equalization is smaller than the RMSE obtained after CMA equalization,indicating that the data dispersion level after MCMA equalization is low;in terms of BER,when BER is 10-3,the optical signal-to-noise ratio required by MCMA is 1.0 dB lower than that of CMA,therefore,MCMA equalization outperforms CMA.The results of this study provide some references for the equalization algorithm in the strong coupling mode-division multiplexing system.