Joint ML timing and phase estimation in OFDM systems using the EM algorithm
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Dosyalar
Tarih
2000
Yazarlar
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Yayıncı
IEEE
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
In this paper, a computationally efficient algorithm is presented for joint maximum likelihood (ML) timing and carrier phase estimation of OFDM systems employing M-PSK modulation scheme with additive Gauissian noise, based on the Expectation-Maximization (EM) algorithm. A nondata-aided(NDA) scheme is considered for the joint timing and phase synchronizer which maximizes the low SNR limit of the likelihood function averaged over the M-PSK signal costellation. For this, an Ehl algorithm is derived which estimates the timing offset and the phase rotations of each subcarrier iteratively and which converges to the true ML estimation of the unknown timing and phase. It is shown that the algorithm becomes independent of the signal-to-noise ratio for both low and high SNR cases. The algorithm is applied to the QPSK modulated OFDM systems and it is concluded that for SNR values greater than 10 dB the convergence is achieved in first iteration and for SNR values less than 10 dB, at most in three iterations. It is also concluded that the convergence is independent of the initial starting points.
Açıklama
Anahtar Kelimeler
Additive noise, Convergence, Gaussian noise, Iterative algorithms, Maximum likelihood estimation, OFDM modulation, Phase estimation, Phase modulation, Signal to noise ratio, Timing, EM algorithm, M-PSK modulation, M-PSK signal constellation, ML estimation, OFDM systems, QPSK, Additive Gaussian noise, Computationally efficient algorithm, Expectation-maximization, Fading channel, Joint ML timing estimation, Likelihood function, Low SNR limit, Multipath, Nondata-aided scheme, Phase rotations, Phase synchronizer, Convergence of numerical methods, Multipath channels, Optimisation, Quadrature phase shift keying
Kaynak
2000 IEEE International Conference on Acoustics, Speech, and Signal Processing.
WoS Q Değeri
N/A
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Cilt
Sayı
Künye
Panayırcı, E. & Georghiades, C. H. (2000). Joint ML timing and phase estimation in OFDM systems using the EM algorithm. Paper presented at the 2000 IEEE International Conference on Acoustics, Speech, and Signal Processing, 2949-2952. doi:10.1109/ICASSP.2000.861152
