Low complexity CFO estimation for OFDMA uplink based on array-antenna

A novel method is proposed for multiuser carrier frequency offset (CFO) estimation for orthogonal frequency division multiple access (OFDMA) uplink with generalized carrier assignment scheme. The base station is equipped with array-antenna. Each user's CFO and direction of arrival (DOA) can be estimated by the DOA-Matrix method utilizing the rotation invariance of the space-domain snapshot matrix. The method is still effective even in fully loaded system with all subcarriers allocated to users, and the computational complexity can be adjusted dynamically according to the system load. Simulation results illustrate the high performance of the proposed algorithm.