改进的16进制正交幅度调制码的相位估计算法

Modified phase estimation algorithm for square-16QAM

相干光通信系统中的相位恢复是克服信号收发端和传输过程中产生的相位噪声的必要步骤。为获得低的运算复杂度和良好的相位估计效果,本文对传统的四次方相位估计算法进行了改进,使之具有自适应的数据块长度控制功能。通过理论分析以及Matlab数值仿真方法验证改进的效果。对于16进制正交幅度调制码(16QAM),改进后的算法在几乎不增加计算复杂度的前提下,比传统算法具有更好的适应性。自适应长度的数据分块方法,有效缓解了传统算法用于16QAM系统时模块大小选择的矛盾。对于25Gbaud的16QAM系统,改进后的算法在10-3的误码率(BER)处,其1dB峰值信噪比(OSNR)代价的激光线宽容差提高了1.8MHz。

Phase estimation is very important for the coherent optical communication systems. A modified carrier phase recovery algorithm with overlap controlled adaptively for squared 16 QAM systems is pro-posed in this paper,which is based on the 4th power algorithm and resolves the problem of block sizechoosing. We simulate the system with Matlab and demonstrate that by using this modified algorithm, the laser linewidth tolerance for 25 G baud 16 QAM system is enhanced by 1.8 MHz at the 10 3 BER level with 1 dB OSNR penalty, compared with the traditional 4th-power algorithm.