An improved method of frequency offset estimation for wireless sensor networks
Zhou Lei-le · Modern Electronics Technique · 2014
MM method is a typical frequency offset estimator,but its SNR threshold raises when frequency becomes larger, to solve this problem,an improved frequency offset estimator based on MM method is proposed. Firstly the average treatment of the autocorrelation function is utilized to reduce the noise. Then frequency offset is roughly obtained by using average value, and the problem of phase ambiguity is solved. At last a more reasonable window function is derived and the final expression of estimation frequency offset is given. Simulation results show that the SNR threshold of the proposed method is at least-1 dB lower than MM method,and the SNR threshold can keep low when the frequency offset increases. The estimation range of the proposed method can reach 90% of the theory value in condition of keeping the SNR threshold-3.5 dB. Additionally,the estimation accuracy is better than MM method when max autocorrelation order is small. The proposed method meets the requirements both in SNR threshold and estimation range in wireless sensor networks.