Browsing by Author "Wu, Tsung-Cheng"

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Dynamic Scheduling-Aided Decoding Strategies for LDPC Convolutional Codes with Rational Parity-Check Matrices
(2011)
Weng, Jian-Jia
;
Wu, Mu-Chen
;
Wang, Chung-Hsuan
;
Su, Yi-Sheng
;
Wu, Tsung-Cheng
In this paper, decoding of LDPC convolutional codes with rational parity-check matrices (LDPC-CC-RPCM) is investigated. We show that Tanner graph of every LDPC-CC-RPCM can always be transformed into an equivalent one with enlarged girth and finite memory order suitable for practical pipeline decoder. Based on the transformed graph, a dynamic scheduling-aided decoding scheme with the enhancement of signal perturbation and error cancellation is presented to improve the convergence speed and bit-error-rate performance in both of the waterfall and error-floor regions. Simulation results also reveal that LDPC-CC-RPCM may outperform ordinary LDPC-CC with polynomial parity-check matrices in some cases under the same code rate and decoding complexity.
Generation of Two-Dimensional Optical Reference Signals Based on Parametric Minimum Cross Entropy
(2011-06-15)
Su, Yi-Sheng
;
Wu, Tsung-Cheng
;
Wang, Chung-Hsuan
;
Chang, Min-Kuan
;
電機工程學系
In this letter, a novel design of two-dimensional (2-D) zero reference codes (ZRCs) based on parametric minimum cross entropy (PMCE) is proposed to generate 2-D optical zero reference signals (ZRSs) with low second maximum for grating alignment systems. An optical ZRS is necessary to obtain an absolute measurement in grating alignment systems. A method to acquire an optical ZRS is by means of illuminating two identical superimposed ZRCs. Because the movement between the two ZRCs is in two-axis, 2-D ZRCs are required. However, they are hard to design due to the high computational complexity, especially for large codes. The proposed PMCE method not only reduces the second maximum of 2-D optical ZRSs, but also decreases the computational complexity. Simulation results indicate that there are 8.33%similar to 22.22% reductions in the second maximum of several 2-D optical ZRSs, as compared with those of the recently proposed cross-entropy (CE) method. The PMCE method proves to be a powerful tool for the design of 2-D ZRCs.