一种改进的编码辅助载波同步算法

编码辅助同步算法利用译码软信息迭代更新同步参数,有效地实现了低信噪比环境下的载波同步。针对目前这类算法存在频偏估计范围小且估计精度受限的问题,设计了一种新的迭代载波同步系统,利用译码软信息分别进行去调制和更新误差信号,在通过改进的频偏估计器补偿频偏之后又结合科斯塔斯环(costas loop)进一步修正相偏,使得译码器和同步器均趋于收敛。仿真结果表明,提出的算法能够大幅提高频偏估计范围,且与理想同步译码相比,最大性能损失不超过0.2 dB。

A modified code-aided carrier synchronization algorithm

The code-aided synchronization algorithm exploits the soft information introduced by the decoder to update synchronization parameter iteratively, it can gain the ideal carrier synchronization performance at low SNR values. Considering that the algorithms perform small frequency offset estimation range and limited accuracy, we propose a new iterative carrier synchronization system to solve the problem. It uses the soft information to eliminate modulation and update the error signal. Based on the increase of the modified frequency estimator which can compensate frequency offset, phase offset is rectified by Costas loop. The synchronizer and decoder tend to converge after several iterations. The simulation results indicate that this algorithm can increase frequency offset estimation range greatly, and the performance degradation is less than 0.2 dB compared with the perfect synchronization decoding performance.