Blind Channel Estimation for Zero-Padding Orthogonal Frequency Division Multiplexing Systems

• Main Authors: Hsu, Yao-Shang, 許堯勝
• Other Authors: Wu, Jwo-Yuh
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/03182687591724833874

碩士 === 國立交通大學 === 電機學院IC設計產業專班 === 97 === In this thesis, we proposed a blind channel identification scheme for zero-padding orthogonal frequency division multiplexing systems with periodic modulating sequence. The proposed method uses the block system model and exploits the channel matrix when some zeros are padded into the source block signal. When block signal is received, we can use its autocorrelation matrix to compute the products of channel coefficient. The channel impulse response vector can be identified, up to a scalar ambiguity, by computing the eigenvector associated with the maximal eigenvalue of a Hermitian matrix, which is formed by the products of channel coefficient. To remove the scalar ambiguity, we design the training symbols which are inserted in the data blocks. To minimize the decrease of channel estimation accuracy caused by channel noise, we design the optimal periodic modulating sequence for zero-padding orthogonal frequency division multiplexing by observing the orthogonality between the noise subspace and the channel product coefficient subspace. After applying the optimal periodic modulating sequence to identify the channel impulse response, zero-forcing equalizer is used to recover the symbol. Comparing to the subspace method, the proposed method is simpler in computation. In the low SNR regime and less data blocks, the proposed method has better performance in channel estimation accuracy and lower symbol error rate.