单通道邻频数字调制混合信号的载波初相估计

Carrier initial phases estimation for single-channel adjacent-frequency mixture of digitally modulated signals

在非合作卫星通信中,针对具有固定帧长和固定帧同步序列的单通道混合信号,根据源信号间的参数差异给出一种同时适用于低阶和高阶混合信号的载波初相估计算法。算法先对去频偏后的帧同步数据以帧长为间隔进行累加,进而根据功率最大化准则对累加结果做定时同步,从而实现对初相信息的提取。为便于比较,同时推导了单通道混合信号载波初相估计的修正克拉美罗界(MCRB,modified Cramer-Rao bound)。仿真结果表明,随着累加帧数的增加,初相估计性能逐渐接近MCRB。

For single-channel mixture of adjacent-frequency digitally modulated signals which have the fixed frame length and sync codes in non-cooperative satellite communications, a carrier initial phases estimation algorithm which can be applied to both low-order and high-order digitally modulated mixtures was provided according to the differences of parameters in the source signals. The sync data eliminated the frequency offset was added in the interval of frame length firstly, then timing synchronization was accomplished for the added result in terms of power maximization rule, thus the initial phases information was derived. Moreover, the modified Cramer-Rao bound （MCRB） of carrier initial phases for single-channel mixture of adjacent-frequency digitally modulated signals was derived for comparison. Simula- tion results show that, difference between estimation performance of the proposed algorithm and MCRB becomes smaller with the increase in the number of added frames.