A robust timing and frequency synchronization for OFDM systems
IEEE Transactions on Wireless Communications
IEEE Journal on Selected Areas in Communications
New timing metric for the frame synchronization in WiMAX OFDMA applications
ICACT'10 Proceedings of the 12th international conference on Advanced communication technology
ICACT'10 Proceedings of the 12th international conference on Advanced communication technology
ICACT'10 Proceedings of the 12th international conference on Advanced communication technology
BER degradation of MC-CDMA at high SNR with MMSE equalization and residual frequency offset
EURASIP Journal on Wireless Communications and Networking
Low-power and high-accurate synchronization for IEEE 802.16d systems
IEEE Transactions on Very Large Scale Integration (VLSI) Systems
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Orthogonal frequency division multiplexing (OFDM) is a parallel transmission scheme for transmitting data at very high rates over time dispersive radio channels. In an OFDM system, frame synchronization and frequency offset estimation are extremely important for maintaining orthogonality among the subcarriers. In this paper, for a preamble having two identical halves in time, a timing metric is proposed for OFDM frame synchronization. The timing metric is analyzed and its mean values at the preamble boundary and in its neighborhood are evaluated, for AWGN and for frequency selective channels with specified mean power profile of the channel taps, and the variance expression is derived for AWGN case. Since the derivation of the variance expression for frequency selective channel case is tedious, we used simulations to estimate the same. Based on the theoretical value of the mean and estimate of the variance, we suggest a threshold for detection of the preamble boundary and evaluating the probability of false and correct detections. We also suggest a method for a threshold selection and the preamble boundary detection in practical applications. A simple and computationally efficient method for estimating fractional and integer frequency offset, using the same preamble, is also described. Simulations are used to corroborate the results of the analysis. The proposed method of frame synchronization and frequency offset estimation is applied to the downlink synchronization in OFDM mode of wireless metropolitan area network (WMAN) standard IEEE 802.16-2004, and its performance is studied through simulations.