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URN etd-0830111-170752 Statistics This thesis had been viewed 2032 times. Download 688 times. Author Meng-Hsiu Hsieh Author's Email Address No Public. Department Communication Engineering Year 2010 Semester 2 Degree Master Type of Document Master's Thesis Language zh-TW.Big5 Chinese Page Count 70 Title STUDY OF HYBRID DCT FOR CHANNEL ESTIMATION OF OFDM SYSTEM Keyword DCT channel estimation OFDM OFDM channel estimation DCT Abstract This thesis is the study of channel estimation based on OFDM modulation communication system. The pilot inserting method is choosing the comb type, and the interpolating method is using hybrid discrete cosine transform (DCT) to reconstruct of the whole frequency domain channel response. Following these steps and we can make the appropriate compensation for the transmission signal to offset the attenuation of the channel.
Comb type pilot placement method put pilots with same intervals in the OFDM symbol in the different sub-carrier. Consequently, we can not only reach the channel estimation but also maintain high transmission efficiency. The use of interpolation algorithm is to obtain the channel response to other sub-carriers which we do not put pilots on. Traditional interpolation algorithms for access the channel effect between pilot and the pilot has certain accuracy, but they can do nothing for the channel outside the pilot. Discrete cosine transform interpolation algorithm proposed by Prof. C.Y. Hsu and S.M. Chen was able to achieve a breakthrough. This method can not only keeping the benefit with the channel response between pilot and pilot but also get a similar extrapolation to reach the data that outside the pilots. In fact, using DCT type II interpolating method can get this. But it needs to change the algorithm during different interpolated sequence, even or odd. It may gain the complexity of the system. To overcome the problem, we use hybrid DCT transform, which forwards by DCT type II and backwards by inverse DCT type I to decrease the complexity of the system.
The thesis simulated with MATLAB SIMULINK. In the simulation, the discrete fourier transform (DFT) interpolation algorithm is proposed as a compared method and using Rayleigh fading model; Rician model plus AWGN as channel response.
Advisor Committee Chau-Yun Hsu - advisor
Che-Ho Wei - co-chair
Tsung-Sheng Kuo - co-chair
Files Date of Defense 2011-07-27 Date of Submission 2011-08-30