الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 99 |  |  |
| | | from | 99 | | |
Abstract
Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency-Division Multiplexing (OFDM) systems and Single-Carrier Frequency-Division Multiple Access (SC-FDMA) are so susceptible to carrier frequency offset (CFO) between transceivers. It occurs due to mismatching between transmitter and receiver causing Doppler shift. CFO causes loss of orthogonality between subcarriers, thus reduce the performance of the system dramatically. In transmission data, multiple users are sending multiple signals were affected by various values of CFO. The frequency spacing and time synchronization of the carriers is chosen in such a way that the carriers are orthogonal, meaning that they do not cause interference to each other. Despite the success and effectiveness of the OFDM systems, it suffers from two well-known drawbacks which are large Peak to Average Power Ratio (PAPR) and high sensitivity to CFO. The presence of the CFO in the received carrier will cause loss of the orthogonality among the carriers. Degrades the performance of OFDM system. It then brings up an increase of Bit Error Rate (BER). In previous work, to get the efficient CFO synchronization, there are a lot of preamble based timing techniques that have been studied. These techniques depend on data aided strategy. In this strategy, transmitting a preamble with good autocorrelation property enables the receiver to reach synchronization. Also, the benefit of correlation products is to improve the estimation of time. In this thesis, A proposed sequence called CAZBAR is proposed. The proposed CAZBAR sequence is based on constant amplitude zero autocorrelation (CAZAC) sequence and barker code. CAZBAR sequence has a better correlation property compared with previous methods. It facilitates estimating carrier frequency offset in communication systems and synchronizes any timing offset. It improves the BER of MIMO-OFDM system. By applying CAZBAR sequence in MIMO SC-FDMA system 2 X 2 and 4x4, the bit error VII rate (BER) performance has improved significantly. At a BER=10-2 , a SNR reduction of 11 dB is achieved for 2 x 2 system and 7 dB reduction for 4 x 4 system compared to other sequences. This improves the performance of the whole system MIMO SC-FDMA. The CAZBAR sequence can be applied in 5G techniques, MIMO-OFDM, and MIMO SC-FDMA systems. Discrete wavelet packet transform/Inverse DWPT (DWPT/IDWPT) is used instead of Fast Fourier Transform/Inverse FFT (FFT/IFFT) in MIMO SC-FDMA and apply Space frequency block coding (SFBC). The CAZBAR sequence is used for estimating CFO. The BER performance of the proposed system space wavelet block coding MIMO single-carrier wavelet division multiple access (SWBC MIMO SC-WDMA) was observed. the SNR reaches 10 dB at BER equals to 10-2 . By comparing the proposed SWBC MIMO SC-WDMA and the proposed MIMO SC-FDMA system, the BER of first one is improved by the last method with BER equals to 3 dB.