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Title: Performance Analysis Of 8 X 8 MIMO-OFDM System Using QOSTBC under Different Fading Channels For Higher Order Modulations
Authors: Kansal, Lavish
Supervisor: Singh, Kulbir
Kansal, Ankush
Issue Date: 21-Jul-2011
Abstract: ABSTRACT With the evolution of the wireless system the demand for high speed data services have been increasing day by day, which is impossible to be achieve by the conventional serial data transmission system without trade-off between high speed data services and QOS without increasing the band width of the system. Here both the options are inconvenient, as one never demands the degradation of the service quality ( because if we increase data rate in serial data transmission ISI will gradually increase which make the extraction of actual information at receiver nearly impossible ) and secondly the need for extra spectrum in a limited spectrum scenario. In order to overcome this problem new parallel data transmission system was proposed, which is known as OFDM system. The performance of OFDM system can further be improved by using multiple antennas at transmitting and receiving side to provide spatial diversity. Multiple antennas can be used at the transmitter and receiver, an arrangement called a MIMO system. A MIMO system takes advantage of the spatial diversity that is obtained by spatially separated antennas in a dense multipath scattering environment. Recently, there have been a lot of interests in combining the OFDM systems with the multiple-input multiple-output (MIMO) technique. These systems are known as MIMO-OFDM systems. MIMO-OFDM system has been currently recognized as one of the most competitive technology for 4G mobile wireless systems. MIMO system can provide the spatial diversity with the help of Space Time Coding when no channel side information is available at the transmitter side. There are different types of Space Time Coding techniques likely Alamouti Space Time Coding, Orthogonal Space Time Coding, Quasi Orthogonal Space Time Coding, etc. Quasi Orthogonal Space Time Coding technique is more preferable over other techniques because it provides more code rate than other Space Time Coding techniques for same no. of transmitting and receiving antennas. In this thesis, a general Quasi orthogonal space time block code (QOSTBC) structure is proposed for multiple-input multiple-output–orthogonal frequency-division multiplexing (MIMO-OFDM) systems for 8 X 8 antenna configuration. The signal detection technology used in this work for MIMO-OFDM system is Zero-Forcing Equalization (linear detection technique). In the present work the analysis of high level of modulations (i.e. M-QAM and M-PSK for different values of M) on MIMO-OFDM system is presented. Here AWGN, Rayleigh and Rician channels have been used for analysis purpose and their effect on BER and Spectral Efficiency for high data rates have been presented. The proposed system has better performance than the other systems in terms of SNR improvement of 3-5 dB and spectral efficiency. The methodology described above is also used to evaluate the performance of the MIMO-OFDM systems using WiMAX Protocols. Here Alamouti 2 X NR Space Time Coding is used for analysis purpose. It is shown that the using multiple antennas at transmitter or receiver side provides significant gains of approximately 2 dB over single transmit single receive antenna (SISO) systems.
Description: M.E. (ECED)
Appears in Collections:Masters Theses@ECED

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