无源反向散射通信系统载波频偏位置快速检测算法

近来无源反向散射通信技术作为绿色物联网的关键技术，引起了广泛的关注。在无源反向散射通信系统中，收发节点与反射节点的振荡器差异、相对运动以及环境变化，导致接收端和发送端存在载波频率偏移(CFO)。CFO对信号检测和系统性能有重要影响，而当前多数无源反向散射通信系统研究忽略了CFO。该文设计了一种适用于频移键控调制(FSK)的CFO快速检测方法，不需要导频就能快速有效检测出CFO是否存在并找出存在的位置。首先，根据信号在CFO存在与否的不同，采用去直流后取模方法对信号进行处理，而后根据处理后的信号的特点，基于累积和(CUSUM)设计快速检测算法对载波频偏出现的位置进行检测，并对理论分析结果进行仿真验证，仿真结果表明取模检测可以有效检测出CFO出现的位置。

A Fast Carrier Frequency Offset Position Detection Algorithm for Passive Backscatter Communication System

Recently, passive backscatter communication technology has attracted extensive attention as one key technology for green Internet of Things. In one typical backscatter communication system, there may exist Carrier Frequency Offset (CFO) between the receiver and the transmitter due to the relative motion or the difference in oscillators or environmental changes. CFO has an important impact on signal detection and system performance, but most current studies ignore the CFO. In this paper, a fast CFO detection method suitable for Frequency Shift Keying (FSK) modulation is designed, which can quickly and effectively detect without pilots whether there exists CFO and find out the location where the CFO begins. Specifically, this paper designs one detector amplitude-taking method. Next, based on CUmulative SUM (CUSUM) algorithm a fast detection algorithm is designed to detect the location of CFO. Finally, simulation results are provided to corroborate the proposed studies. The simulation results show that the designed detector can effectively locate the position where CFO appears.