Mémoires de Fin d’Etudes
Etablissement
Université de Sidi Bel Abbès - Djillali Liabes
Affiliation
Département d’Electronique
Auteur
ZERROUKI, Abderrahmane ahmed
Directeur de thèse
Dr. SEDDIKI ALI (Maitre de conférence)
Filière
Télécommunication
Diplôme
Doctorat
Titre
Progressive Image Transmission Over MIMO-OFDM System Based On Dual Tree Complex Wavelet Transform
Mots clés
MIMO, OFDM, DC-CWT, FFT, STBC, SPIHT , Progressive image transmission
Résumé
Orthogonal Frequency Division Multiplexing (OFDM) is one of the most promising physical layer technologies for high data rate wireless communications due to its robustness to frequency selective fading, high spectral efficiency, and low computational complexity. OFDM can be used in conjunction with a Multiple-Input Multiple-Output (MIMO) transceiver to increase the diversity gain and/or the system capacity by exploiting spatial domain. Because the OFDM system effectively provides numerous parallel narrowband channels, MIMO-OFDM is considered a key technology in emerging high-data rate systems such as 4G, IEEE 802.16, and IEEE 802.11n. Traditionally, orthogonal frequency division multiplexing (OFDM) is implemented using fast Fourier transform (FFT). However, FFT has a major drawback arising from using rectangular window, which creates side lobes. Moreover, the pulse shaping function used to modulate each subcarrier extends to infinity in the frequency domain. This leads to high interference and lower performance levels. Intercarrier interference (ICI) and intersymbol interference (ISI) can be avoided by adding a cyclic prefix (CP) to the head of OFDM symbol. But, this reduces the spectrum efficiency. The wavelet packet modulation (WPM) system has a higher spectral efficiency and better robustness towards inter-channel interference than the conventional OFDM system. Moreover, WPM is capable of decomposing the time frequency plane in flexible way through filter bank (FB) constructions. However, the major problem with the common discrete wavelet packet transform (DWPT) is its lack of shift invariance; which means that on shifts of the input signal, the wavelet coefficients vary substantially. We propose an MIMO-OFDM system based on Dual Tree Complex Wavelet Transform (DTCWT), where the DT-CWT is used to replace the Fast Fourier Transform (FFT) in the conventional OFDM. Our goal is the study of the performance of the proposed scheme using Space–Time Block Codes (STBC) as a spatial diversity technique (MIMO) to decrease the fading effects in both time and frequency domain for the OFDM system based on Dual Tree Complex Wavelet Transform (DTCWT) with SPIHT encoded progressive image transmission.
Statut
Validé