一种适应于IEEE 802.15.4k标准的高精度频偏估计算法  

High-Accuracy Frequency Offset Estimation Algorithm Based on IEEE 802.15.4k

作　　者：叶晓青[1,2] 罗炬锋 邱云周[1,2] 朱元萍 黄河笑[3] Ye Xiaoqing;Luo Jufeng;Qiu Yunzhou;Zhu Yuanping;Huang Hexiao(Shanghai Institute of Microsystem and Information Technology,Chinese Academy of Sciences,Shanghai,200050,China;Shanghai Internet of Things CO.,LTD.,Shanghai, 201899,China;College of Science and Technology,Shanghai Open University,Shanghai,200433,China)

机构地区：[1]中国科学院上海微系统与信息技术研究所,上海200050 [2]上海物联网有限公司,上海201899 [3]上海开放大学理工学院,上海200433

出　　处：《数据采集与处理》2018年第1期58-64,共7页Journal of Data Acquisition and Processing

基　　金：上海市科技基金(15DZ1100400)重大资助项目;国家自然科学基金(61471347)资助项目

摘　　要：为实现基于IEEE 802.15.4k标准的长码字直接序列扩频系统(Direct sequency spread spectrum,DSSS)在低信噪比下的频偏估计,提出一种高精度、稳定的改进频偏估计算法。该算法在保证频偏估计范围的前提下同时利用相位和幅度信息对信号作有偏自相关和迭代,提高包含相位信息的序列的信噪比,然后对有偏自相关信号的各阶差分计算相位幅角并加权平均,克服了Fitz方法在低信噪比下近似条件难以满足的缺点。实验结果表明该算法能在不缩小估计范围的同时实现极低信噪比下的精确频偏估计,估计精度满足IEEE 802.15.4k标准下接收系统对残余频偏的容忍度。In order to implement the frequency offset estimation in direct sequency spread spectrum(DSSS)system based on the standard of IEEE 802.15.4k under low SNR circumstance,an improved frequency offset estimation algorithm with high accuracy and stability is proposed in this paper.The proposed algorithm firstly makes biased auto correlation and iteration to the signals by using the phase and amplitude information at the same time under the premise of ensuring the frequency offset estimation range,which improves the SNR of sequences including the phase information.And then it calculates the phase angles for each order difference of biased auto correlation signals and makes a weighted mean,which overcomes the difficulty in meeting approximate conditions for Fitz method under low SNR circumstance.The simulation results show that the proposed method can achieve high accuracy estimation without reducing the estimation range under extremely low SNR circumstance,and the estimation precision meets the tolerance to residual frequency offset for the receiving system under the standard of IEEE 802.15.4k.

关 键 词：直接序列扩频 低信噪比 频偏估计 有偏自相关 IEEE 802.15.4k 

分 类 号：TN911[电子电信—通信与信息系统]