中文摘要：

针对低信噪比下QAM信号的载波相位跟踪问题,提出一种基于信号合成的联合载波相位跟踪算法。该算法采用判决引导载波恢复环结构,在各路信号分别进行相位捕获后,进行最大比合成与联合相位跟踪。理论分析与仿真结果表明,该算法通过信号合成,有效提高信号质量,降低误码率;利用合成符号进行联合相位跟踪,大大降低了低信噪比下相位估计误差。该联合载波相位跟踪算法在解调符号端合成,复杂度低,易于实现。

英文摘要：

A joint carrier-phase-tracking algorithm based on signal combining is proposed for carrier phase tracking of quadrature amplitude modulation（QAM） signals.Adopting decision-directed phase-locked loop（DD-PLL）,after phase acquisition of single channel signals independently,multi-channel signals are combined in maximal ratio combining,and joint phase tracking is carried through.Analysis and simulation results show that the algorithm improves signal quality and degrades symbol error ratio（SER） effectively.The combined symbol is utilized to carry through joint phase tracking,degrading phase estimation error over low signal-to-noise-ratio（SNR） substantially.The signals are combined after being demodulated,so it is in low complexity.