摘要
在使用直接序列扩频技术进行抗干扰的通信系统中,针对突发帧的情形,需在每个数据帧的帧头进行帧同步。频率偏移和时间偏移对帧同步过程有较大影响,因此要进行准确的频偏估计和时偏估计。为了保证数据帧抗干扰的能力,伪码长度会较长,此时频率偏移对相关峰的影响很大,采用分段相关的方法减小频偏影响;直接在时域进行相关运算,运算量极大,通过采用基于FFT的伪码并行捕获方法,大大减少了计算量。该方法是以FFT窗口大小为接收数据的移动长度,无需逐个运算伪码,只需根据FFT变换及运算后的结果进行偏移,此时接收数据伪码要与2个相位状态的本地伪码进行频域相关运算,针对这一特点提出利用相关峰进行时偏估计的改进策略,并与原有策略进行比较,时偏估计失败率要远低于传统策略。
In an anti-interference network using Direct Sequence Spread Spectrum for burst data,it is necessary to implement frame synchronization at the beginning of each frame.Synchronization is greatly affected by frequency offset and timing offset,so it is necessary to implement accurate frequency offset estimation and timing offset estimation.There has to be a kind of much longer PN code for antiinterference,which makes the effect of frequency offset more obvious. Segmentation correlation is used to decrease the influence of frequency offset.At the same time,the long PN code leads to a large amount of calculations in time domain.FFT is used for simplifying calculations.This method in frequency domain moves the received data by the step of the FFT window size instead of the chip. It only needs to implement offset after FFT to find the timing location. An improved algorithm is proposed for the moving FFT window and is compared with the traditional method.Simulation shows that the proposed method is much better than the traditional one.
作者
何骥
周建人
HE Ji ZHOU Jian-ren(The 54th Research Institute of CETC, Shijiazhuang Hebei 050081, China)
出处
《无线电通信技术》
2017年第2期16-20,共5页
Radio Communications Technology
基金
国家部委基金资助项目
关键词
帧同步
伪码捕获
FFT变换
时偏估计
frame synchronization
PN code acquisition
FFT
timing offset estimation
