改进科斯塔斯环的LDPC码相位同步算法

Iterative phase synchronization algorithm based on modified Costas loop for LDPC coded systems

提出了一种基于改进科斯塔斯环的LDPC编码系统迭代相位同步算法.该算法用LDPC译码过程中每次迭代产生的数据符号的后验概率更新科斯塔斯环中的错误信号,从而以迭代的方式达到相位同步.该算法将LDPC译码过程和科斯塔斯环相位同步过程以迭代方式相结合,仿真表明,在系统存在一定程度频率偏移的条件下该算法能对相位错误进行有效的盲估计,且对一定程度频率偏移具有很强的鲁棒性.

An iterative phase synchronization algorithm for LDPC coded systems based on the modified Costas loops was proposed. In the modified Costas loop, the posterior probabilities from the LDPC iterative decoder were used to help update the error signal. In this algorithm, the iterafive decoding and Costas loop based phase error recovery went together iteration after iteration： The simulation results show.that the proposed algo- rithm can estimate blindly and effectively the carrier phase error, and is robust with some frequency offset.