Optimal CFO and channel estimation for OFDMA uplink using importance sampling

In this paper, we derive the optimal carrier frequency offset (CFO) and channel estimator for OFDMA uplink based on joint maximum likelihood (ML) criterion. Direct implementation of the resultant estimation scheme is quite challenging due to the need of multi-dimensional exhaustive search in multi-CFO estimation. To solve this problem, a computationally efficient method using importance sampling technique is proposed. Without the need of providing initial estimate, the proposed estimator guarantees to generate the global optimal solution. Simulation results clearly verify the effectiveness of the proposed estimation scheme.