关键词: 长期演进（LTE）, 频偏估计, 减小多径影响, 抗极性反转, 扩大频偏估计范围

Abstract: This paper researches the carrier frequency sychronization for downlink of LTE system and analyzes two traditional Carrier Frequency Offset（CFO） estimation algorithms which are the estimation based PSS correlation and the Max-Likelihood（ML）estimation based on Cycle Prefix（CP）. Aiming at the latter algorithm has the shortcomings that are a poor ability to resist multipath and polarity reversion and a smaller estimation scale, this paper proposes an improved algorithm. This improved algorithm reduces the influence of multi-path through substracting a part of interferenced data from the CP when using the CP to estimate the CFO. To expand the estimation scale and enhance the ability of resisting the polarity reversion, this improved algorithm uses the polarity information of the estimated result of algorithm based on PSS correlation. The simulations show that, the improved algorithm has a better performance in the multi-path condition compared to the original algorithm, when [|εF|] approach to 0.5, the original algorithm can resit the polarity information effectively and has good robust ability to the changement of [|εF|] nearby 0.5, when [|εF|>0.5], the original algorithm is invalid but the improved algorithm still can estimate the [εF] and keep a higher estimation performance.

Key words: Long Term Evolution（LTE）, Carrier Frequency Offset（CFO） estimation, reducing influence of multi-path, resisting polarity reversion, expanding estimation scale