Joint multiple CFOs and channel estimation for uplink OFDMA systems without noise statistics

In this paper, an H_∞ based method is proposed to jointly estimate the multiple carrier frequency offsets (CFOs) and the channel impulse responses (CIRs) for uplink orthogonal frequency division multiplexing access (OFDMA) systems in the unknown noise. The design criterion of the proposed algorithm is to guarantee that the effect of worst-case disturbances on the CFOs estimation errors is smaller than a prescribed disturbance level. Since any knowledge of the disturbance does not be required, the proposed estimator can achieve a good CFOs and channel estimation performance in the non-Gaussian noise. Simulation results show that the proposed H_∞ method can combat inter-carrier interference (ICI) introduced by multiple CFOs effectively, and improve the robustness performance of uplink OFDMA systems against non-Gaussian noise.