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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 recovery in coherent optical communication systems is a necessary step to overcome the phase noise generated at the transmitting and receiving end of the signal and in the transmission. In order to obtain low computational complexity and good phase estimation effect, this paper improves the traditional quadratic phase estimation algorithm to make it have adaptive data block length control function. Through theoretical analysis and Matlab numerical simulation method to verify the improvement effect. For 16QAM, the improved algorithm has better adaptability than the traditional algorithm with little increase of computational complexity. Adaptive length of the data block method, effectively alleviate the traditional algorithm used in 16QAM system, the choice of module size conflicts. For a 25Gbaud 16QAM system, the improved algorithm provides a 1.8MHz increase in laser linewidth tolerance at a BER of 10-3 for a 1dB peak OSNR penalty.