非合作通信中MQAM的定时载波联合同步

Joint carrier synchronization and symbol timing for MQAM in non-cooperation communication systems

针对非合作通信系统中多径信道下含有大符号率偏差的M进制正交振幅调制信号定时载波的同步问题,提出了一种基于改进加德纳算法的M进制正交振幅调制信号定时载波联合同步方法.该方法首先利用加德纳算法中频偏与算法输出值之间的关系,进行定时偏移估计与载波偏移粗估计;然后利用与其相差半个码元的定时误差检测输出值的绝对值差进行锁定;最后利用锁相环跟踪细微的频偏和相偏.仿真结果表明,在多径信道下,所提的定时偏移和载波偏移的联合估计方法具有良好的估计性能.

Aiming at the problem of symbol timing and carrier synchronization of （M-ary Quadrature Amplitude Modulation） MQAM signals with large symbol rate deviation in non-cooperative communication systems under multipath channels, a new method based on the improved Gardner algorithm for MQAM signal timing carrier joint synchronization is proposed. First, the method obtains timing offset estimation and carrier offset coarse estimation using the relationship between frequency offset and output value of the Gardner algorithm. Then, locking is performed with the difference of the absolute value between estimation and the output value of timing error detection which is half a symbol different from the estimation. Finally, the method uses the phase-locked loop to track the fine frequency offset and phase offset. Simulation result shows that the proposed joint estimation method of timing offset and carrier offset has a good estimation performance under the condition of multipath channels.