Title :
Fine frequency synchronization in the uplink of multiuser OFDM systems
Author :
Häring, Lars ; Bieder, Stefan ; Czylwik, Andreas
Author_Institution :
Dept. of Commun. Syst., Univ. Duisburg-Essen, Duisburg, Germany
fDate :
12/1/2009 12:00:00 AM
Abstract :
This contribution considers the estimation and compensation of residual multiple carrier frequency offsets (CFOs) and sampling frequency offsets (SFOs) in the uplink of multiuser OFDM systems. Based on the observation of a user-dependent phase rotation, an approximate maximum-likelihood (ML) estimator is proposed in order to estimate the CFOs and SFOs and to track the phase in a post-synchronization step. By using a Taylor approximation, the estimation complexity is reduced. Bit error-ratio (BER) simulations show that the system performance degradation due to (small) frequency mismatches is negligible if the proposed method is applied.
Keywords :
OFDM modulation; approximation theory; communication complexity; error statistics; maximum likelihood estimation; synchronisation; BER simulations; Taylor approximation; approximate maximum-likelihood estimator; bit error-ratio simulations; estimation complexity; frequency synchronization; multiuser OFDM systems; orthogonal frequency division multiplexing; residual multiple carrier frequency offsets; sampling frequency offsets; user-dependent phase rotation; Bit error rate; Degradation; Doppler shift; Frequency estimation; Frequency synchronization; Maximum likelihood estimation; OFDM; Oscillators; Phase estimation; Sampling methods; Carrier frequency offset; OFDM; multiuser; sampling frequency offset; uplink;
Journal_Title :
Communications, IEEE Transactions on
DOI :
10.1109/TCOMM.2009.12.080305
