Browsing by Author "Chen, Yi-Sheng"

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Blind channel identification for MIMO single carrier zero padding block transmission systems
(2006)
Chen, Yi-Sheng
;
Lin, Ching-An
;
電控工程研究所
;
Institute of Electrical and Control Engineering
We propose a blind identification method for MIMO single carrier zero padding block transmission systems. The method uses periodic precoding on the source signal before transmission. The estimation of channel impulse response matrix consists of two steps: (i) obtain the channel product matrix by solving a lower-triangular linear system and (ii) obtain the channel impulse response matrix by computing the positive eigenvalues and eigenvectors of a Hermitian matrix formed from the channel product matrix. A sufficient condition for identifiability is simply that the channel impulse response matrix is full column rank. The design of the precoding sequence to minimize the noise effect in covariance matrix estimation is proposed. Simulation examples are used to demonstrate the performance of the method.
Blind identification of MIMO channels using optimal periodic precoding
(2007-04-01)
Lin, Ching-An
;
Chen, Yi-Sheng
;
電控工程研究所
;
Institute of Electrical and Control Engineering
We propose a method for blind identification of multiple-input mutiple-out (MIMO) finite-impulse response (FIR) channels that exploits cyclostationarity of the received data induced at the transmitters by periodic precoding. It is shown that, by properly choosing the precoding sequence, the MIMO FIR transfer functions, with M-t inputs and M-r outputs, can be identified up to a unitary matrix ambiguity. The transfer functions need not be irreducible or column reduced, and there can be more outputs (M-r >= M-t) or more inputs (M-r < M-t). The method exploits the linear relation between the covariance matrix of the received data and the "channel product matrices". The method is shown to be robust with respect to channel-order overestimation. The proposed algorithm requires solving linear equations and computing the nonzero eigenvalues and eigenvectors of a Hermitian positive, semidefinite matrix. The performance of the algorithm, and indeed the identifiability, depends on the choice of the precoding sequence. We propose a method for optimal selection of the precoding sequence which takes into account the effect of additive channel noise and numerical error in covariance matrix estimation. Simulation results are used to demonstrate the performance of the algorithm.
Blind-Channel Identification for MIMO Single-Carrier Zero-Padding Block-Transmission Systems
(2008-07-01)
Chen, Yi-Sheng
;
Lin, Ching-An
;
電控工程研究所
;
Institute of Electrical and Control Engineering
We propose a blind identification method for multiple-input multiple-output (MIMO) single-carrier zero-padding block-transmission systems. The method uses periodic precoding on the source signal before transmission. The estimation of the channel impulse response matrix consists of two steps: 1) obtain the channel product matrix by solving a lower-triangular linear system; 2) obtain the channel impulse response matrix by computing the positive eigenvalues and eigenvectors of a Hermitian matrix formed from the channel product matrix. The method is applicable to MIMO channels with more transmitters or more receivers. A sufficient condition for identifiability is simply that the channel impulse response matrix is full column rank. The design of the precoding sequence which minimizes the noise effect in covariance matrix estimation is proposed and the effect of the optimal precoding sequence on channel equalization is discussed. Simulations are used to demonstrate the performance of the method.
Correlation of surface processes with characteristic sensing responses of PdO thin films to ethanol
(2019-04-15)
Cheng, I-Kai
;
Wang, Jeng-Han
;
Tsai, Cheng-Yu
;
Chen, Yi-Sheng
;
Pan, Fu-Ming
Gas sensing characteristics of PdO nanoflake thin films exposed to ethanol (EtOH) at temperatures below 250 degrees C was studied. The PdO thin film responses distinctly to 0.15 ppm EtOH in dry air at temperatures above 100 degrees C. A characteristic valley-shaped response feature develops in the early stage of the exposure to EtOH at 150 degrees C and above. Formation of the valley feature is a result of the combined effects of two types of surface processes, which successively modify the sensor conductance in the opposite way. Dehydrogenation of adsorbed EtOH induces reduction of preadsorbed oxygen anions and the PdO substrate, resulting in the drop of the conductance. On the other hand, subsequent adsorption of EtOH and oxygen on newly growing Pd nanoclusters, which develop due to the reduction of the PdO substrate, causes the increase in the conductance. The Pd nanoclusters can be later reoxidized in the EtOH gas mixture, thereby modifying the sensing behavior of the PdO sensor. X-ray photoelectron spectroscopy (XPS), diffusive reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature programmed desorption (TPD) were used to study adspecies and gaseous species formed in the EtOH gas sensing reactions. On the basis of the characteristic electrical response and chemical characterizations, we proposed the formation mechanism for the characteristic response feature.
Ethanol gas sensing mechanism of PdO nanoflake thin film at temperatures below 250 degrees C
(2017-04-02)
Cheng, I-Kai
;
Wang, Jeng-Han
;
Tsai, Cheng-Yu
;
Chen, Yi-Sheng
;
Pan, Fu-Ming
Statistical Covariance-Matching Based Blind Channel Estimation for Zero-Padding MIMO-OFDM Systems
(2009)
Chen, Yi-Sheng
;
Wu, Jwo-Yuh
;
交大名義發表
;
National Chiao Tung University
We propose a statistical covariance-matching based blind channel estimation scheme for zero-padding (ZP) MIMO-OFDM systems. By exploiting the block Toeplitz channel matrix structure, it is shown that the linear equations relating the entries of the received covariance matrix and the outer product of the MIMO channel matrix taps can be rearranged into a set of decoupled groups. The decoupled nature reduces computations, and more importantly guarantees unique recovery of the channel matrix outer product under a quite mild condition. Then the channel impulse response matrix is identified, up to a Hermitian matrix ambiguity, through an eigen-decomposition of the outer product matrix. Simulation results are used to evidence the advantages of the proposed method over a recently reported subspace algorithm applicable to the ZP-based MIMO-OFDM scheme.
Statistical covariance-matching based blind channel estimation for zero-padding MIMO-OFDM systems
(2012)
Chen, Yi-Sheng
;
Wu, Jwo-Yuh
;
交大名義發表
;
National Chiao Tung University
We propose a statistical covariance-matching based blind channel estimation scheme for zero-padding (ZP) multiple-input multiple-output (MIMO)-orthogonal frequency division multiplexing (OFDM) systems. By exploiting the block Toeplitz channel matrix structure, it is shown that the linear equations relating the entries of the received covariance matrix and the outer product of the MIMO channel matrix taps can be rearranged into a set of decoupled groups. The decoupled nature reduces computations, and more importantly guarantees unique recovery of the channel matrix outer product under a quite mild condition. Then the channel impulse response matrix is identified, up to a Hermitian matrix ambiguity, through an eigen-decomposition of the outer product matrix. Simulation results are used to evidence the advantages of the proposed method over a recently reported subspace algorithm applicable to the ZP-based MIMO-OFDM scheme.