Iterative approach for multiuser carrier frequency offset estimation in interleaved OFDMA uplink

In this paper, the issue of carrier frequency offset (CFO) estimation in interleaved orthogonal frequency division multiple access (OFDMA) uplink systems is investigated. The problem of peaks ambiguity in MUSIC estimator proposed by Cao and Yao is analyzed firstly, and then a searching solution is presented. Furthermore, a new iterative algorithm based on this MUSIC estimator is proposed. The proposed approach iteratively searches for the correct CFO vector by minimizing the objective function using a first-order Taylor series approximation of the CFO vector. It can conquer the effect of ambiguous peaks effectively, performs better than Cao and Yao's approach in relatively low SNR region and large CFO, and at the same time has much lower computational complexity. Simulations illustrate the efficiency of the proposed algorithm.