无线传感网载波频率偏移估计方法的改进  

Improved carrier frequency offset estimation algorithm for wireless sensor networks

作　　者：王翔[1] 罗炬锋[1] 付耀先[1] 王营冠[1] 

机构地区：[1]中国科学院上海微系统与信息技术研究所无线传感器网络与通信重点实验室,上海200050

出　　处：《计算机应用研究》2011年第9期3428-3431,共4页Application Research of Computers

基　　金：国家重大专项项目资助(2009ZX03006-003);国家"973"计划资助项目(2011CB302901)

摘　　要：无线传感网的低功耗、低成本等特性,要求设备能在低信噪比环境下快速完成突发通信的载波频偏估计,保证数据传输的正确性,因而需要对低信噪比和大频偏范围的频偏估计算法进行研究。Fitz算法是较为经典的载波频率偏移估计方法,具有算法精确度高和估计信噪比门限低等优点,但此算法的频偏估计范围与精度之间呈反比关系,频偏估计范围越大,估计精度越低。针对Fitz算法进行改进,利用迭代的方法展开信号自相关相位,代入Fitz算法估计载波频偏,在保持Fitz算法精确度高和估计信噪比门限低优点的同时,将其估计范围扩大了M倍,M为最大自相关阶数。实验结果表明,改进算法的频偏估计范围接近±50%的符号周期,估计精确度接近克拉美—劳(CRLB)下限,估计信噪比门限较其他算法降低2 dB;算法能够同时满足无线传感网系统对载波频偏估计范围和估计精度的需求。In wireless sensors networks,for low-power and low-cost requirements,the device should rapidly complete accurate carrier frequency offset estimation in low SNR environment to ensure reliable data transmission.It is necessary to develop the estimation algorithm of low SNR and large estimation range.Fitz algorithm is a classical method of frequency offset estimation,with advantage of high accuracy and low estimation SNR threshold.But it is inverse relationship between the estimation range and the estimation accuracy.This paper introduced a new iterative method to improve Fitz＇s algorithm which unwrapped the angular of auto-correlation function to calculate the carrier frequency offset.The new algorithm expanded the estimate range while kept the advantages of high accuracy and low estimation thresh of Fitz algorithm.The simulation results show that the new algorithm＇s estimation range close to ± 50% of the symbol period,the estimation accuracy close to lower limit of to the CRLB,and the estimation SNR threshold 2 dB lower than other algorithms.This algorithm can meet the accuracy and range requirement of wireless sensor network at the same time.

关 键 词：无线传感网 载波频率 频率偏移估计 迭代 

分 类 号：TN929.5[电子电信—通信与信息系统]