Théses de doctorat

Permanent URI for this collection

https://depo.univ-annaba.dz//handle/123456789/146

Browse

Browsing Théses de doctorat by Author "ATOUI Sakina"

Now showing 1 - 1 of 1
  • No Thumbnail Available
    Item
    Méthodologie pour la séparation de mélanges de signaux OFDM
    (2021-01-28) ATOUI Sakina
    In this thesis, the orthogonal frequency division multiplexing (OFDM) technique envisioned for fifth-generation wireless networks is studied. This promising technique can overcome the intersymbol interference (ISI) which results from the time-dispersive nature of wireless channels. First, the basic principles of this technique͢—orthogonality, cyclic prefix (CP), fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT)—are explained. An efficient implementation of the OFDM technique is also described. The OFDM impairments are presented, and the carrier frequency offset (CFO) effect is analyzed in detail. Several techniques that mitigate intercarrier interference (ICI) are discussed and some basic methods are presented. In particular, the maximum likelihood estimation (MLE) is reviewed in detail. A blind frequency offset estimator that uses the correlations between the remodulated sequence on the receiver side and the conventional received symbol is presented, and a closed form solution is derived. The proposed estimator is derived under short intervals when the correlation is high, so it has low computational complexity. Lin and Beek’s estimators are used for comparison. Simulations demonstrate the effectiveness of the proposed estimator under a Rayleigh fading channel. The proposed estimator can be implemented efficiently using the OFDM system. Under the same system configuration, simulation results demonstrate the excellent performance of the proposed estimator when compared to the performance of other techniques for any signal-to-noise (SNR) value.