一种新的LTE系统频偏估计算法

相位差分算法是LTE系统中经典的频偏估计算法,受LTE信号结构的限制,其估计范围较小且不能工作于跳频传输模式.针对相位差分算法的缺点,提出了一种基于互相关函数能量比的频偏估计算法.该算法根据LTE上行链路PRACH信道中ZC序列循环移位和频偏之间的关系,利用接收ZC序列与原始序列的互相关函数和接收ZC序列与原始序列的单位循环移位序列的互相关函数的能量比来估计频偏,可增大频偏估计范围,减少信噪比对估计误差的影响,且不受跳频传输的影响.仿真结果表明,相比传统的相位差分算法,该算法频偏估计范围更大,估计精度随信噪比变化较小,可有效改善LTE系统频偏估计性能.

A New Frequency Offset Estimation Algorithm of LTE System

Phase difference algorithm is the classical frequency offset estimation algorithm of long term evolution (LTE) system,which has small estimation range and fails in frequency hopping (FH) transmission mode due to the limitation of LTE signal structure.A cross correlation function power ratio algorithm is proposed to overcome the defects of phase difference algorithm.According to the relation between the cyclic shift of Zadoff-Chu(ZC) sequence and frequency offset in LTE uplink physical random access channel (PRACH),the cross correlation function between received ZC sequence and original sequence and the power ratio of cross correlation function between received ZC sequence and unit cyclic shift of original sequence are used to estimate frequency offset,which can expand the estimation range and decrease the influence caused by Signal-to-Noise Ratio (SNR),and are not affected by FH transmission mode.The simulation results show that the proposed algorithm has larger estimation range and lower MSE compared with traditional phase differential algorithm and can improve the frequency offset estimation performance of LTE system.