AQPSK调制系统中一种自动频偏纠正算法

在移动通信系统中,移动台(mobile station,MS)需要与基站(base station,BS)保持频率同步,因此在移动台接收机中通常都会采用自动频偏补偿机制(automatic frequency compensation,AFC)。通常情况下,AFC会根据本机晶振和频偏估计(frequency offset estimation)结果来直接调整频偏补偿值。但是,在某些信道条件恶劣的特殊场景下,FOE的结果可能存在很大错误,这种错误会导致AFC系统崩溃。本文提出一种新的自动频偏补偿算法,可以改进AFC环路控制,以抵抗恶劣信道对接收机的影响。

AFC Algorithm in AQPSK Modulation System

In the wireless communication system, the mobile station (MS) needs to synchronize with the frequency of the base station (BS), so automatic frequency control (AFC) is mandatory in the MS receiver. Usually the AFC adjusts the local oscillator according to the frequency offset estimation (FOE) results directly. But there will be large error of the FOE results in some extremely critical channel conditions, and these errors may lead the local oscillator drifting away. This invention aims to make the AFC loop more stable in bad channel conditions.