一种降低复杂度的迭代载波同步算法

A complexity-reduced iterative carrier synchronization algorithm

针对低信噪比环境下编码辅助载波同步算法存在复杂度高和实时性差的问题,本工作引入估计积分器不断补偿信号向量、减小待估偏移值.在此基础上,提出新的同步迭代停止准则;当LDPC码的各变量节点的对数似然比绝对值的均值趋于稳定时,提前停止迭代.仿真结果表明,该算法在缩小频率搜索范围的同时,大大减少同步迭代次数,且与理想同步译码相比,性能损失不超过0.12 dB.

We consider high complexity and long delay of the code-aided carrier synchronization algorithm at low SNR（signal to noise ratio）.We use the estimation integrator for compensating signal vector and decreasing offset to be estimated.A new iterative synchronization stopping rule is proposed.The system will stop iteration if the mean of the absolute values of LLR（log-likelihood ratio） message at the output of LDPC decoder keeps steady.The simulation results indicate that this algorithm narrows the frequency search range and the average number of iterations is reduced greatly.It also shows that the performance loss is not larger then 0.12 dB.