Low-Complexity Carrier Frequency Offset Estimation Algorithm in TD-LTE

Frequency offset estimation is an important module in the downlink synchronization process of orthogonal frequency division multiplexing (OFDM) system. Research on frequency synchronization of OFDM, a lowcomplexity and efficient method is proposed to evaluate frequency offset in this paper. In general, maximum likelihood (ML) based on cyclic prefix (CP) and primary synchronization signal (PSS) frequency-domain crosscorrelation algorithm are applied for fractional carrier frequency offset estimation. PSS time-domain crosscorrelation algorithm is used to estimate integral carrier frequency offset. However, for fractional carrier frequency estimation, the performance of ML based on CP degrades in fading channel. The complexity of the other algorithm is high. Also, the conventional integral carrier frequency estimation requires cross-correlation between the received PSS and local PSS or auto-correlation of received PSS, so they also have great complexity. In this paper, relying on the PSS time center-symmetric property, we perform PSS autocorrelation method twice in the time domain. Hence fractional carrier frequency offset is obtained and compensated. Next, relying on the PSS frequency centersymmetric property, we perform energy difference computations to estimate the integral carrier frequency offset, which is equal to the distance between the calculated minimum and the central frequency in frequency domain. Simulation results demonstrate that the proposed algorithm can estimate frequency offset accurately, guarantee the reliance and reduce complexity in comparison with the normal methods.