Low Complexity Blind Frequency Offset Estimation Based on Downsampling for OFDM Systems

A novel subspace-based blind carrier frequency offset (CFO) estimation approach for orthogonal frequency-division multiplexing (OFDM) systems is proposed. The key observation is that the CFO information is redundant in spectrum structure. By locating null carriers equispaced and remodeling the received blocks through downsampling, we compact parameter space and obtain a low complexity estimator with the performance of high-resolution. Analysis and simulations show the estimator is robust in both AWGN channel and frequency-selective channel.