Performance of Subspace Based Multi-user CFO Estimation for Interleaved OFDMA Uplink

In order to synchronize multi-user Orthogonal Frequency Division Multiplex Access (OFDMA) system at the uplink carrier frequency offset (CFO) has to be estimated. In this paper we analyze the performance of subspace based CFO estimation algorithm for multi-user OFDMA recently proposed in the literature. It is shown that CFO estimation error is insensitive to user's channel type because signal structure is conserved. Simulation confirms that subspace based algorithms are very robust to the nearfar effect. The floor in root-mean square of estimation error is observed in the case of inter symbol interference. Algorithm behavior at low SNR values is analyzed and also the sensitivity to subspace dimension.