Carrier-Frequency Offset Estimation for OFDMA Uplink Based on ML and ESPRIT Method

Carrier Frequency offsets in OFDMA system will introduce InterCarrier Interference (ICI) and consequently degrade the system performance. A new frequency offset estimation algorithm for OFDMA system based on the combination of ESPRIT (Estimation of Signal Parameters by Rotational Invariance Techniques) and the Maximum Likelihood (ML) estimation method is proposed. The subset of the frequency offsets first is estimated by ESPRIT, then the frequency offset of each user is identified in the subset by the ML estimation method. The algorithm greatly decreases the complexity of N-dimensional search processes of ML method and efficiently solves the problem of multi-frequency offsets estimation.