Chang-Ming Lee

National Chiao Tung University, Hsin-chu-hsien, Taiwan, Taiwan

Are you Chang-Ming Lee?

Claim your profile

Publications (5)3.96 Total impact

  • Chang-Ming Lee, Yu.T. Su
    [Show abstract] [Hide abstract]
    ABSTRACT: We present a novel stochastic decoding algorithm for Reed-Solomon codes. We apply an iterative Monte Carlo based approach called the Cross-Entropy method to produce, in every iteration, a set of random error locator vectors, each indicates n - k possible erasure positions within a received word. We associate each error locator vector with a candidate codeword by erasures-only decoding the received word, using the error locator vector to locate the erasures. Each iteration results in a new elite set that contains the best E candidate codewords. To increase the search radius and enhance the decoder performance we use the randomly drawn samples to generate what we call virtual received words from which extra candidate codewords and thus candidate elite members can be obtained. The proposed algorithms offer both complexity and performance advantages over some existing algebraic decoding algorithms for high rate RS codes.
    IEEE Signal Processing Letters 09/2009; · 1.67 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Implementing a belief propagation (BP) based LDPC decoder requires high degrees of parallelism using many component soft-in soft-output (SISO) decoding units to perform message passing from variable nodes to check nodes or vice versa. An obvious complexity-reduction solution is to serialize the decoding process, i.e., dividing a decoding iteration into several serial sub-iterations in which a sub-iteration performs only part of the complete parallel message-passing operation. The group horizontal shuffled BP (GHSBP) and vertical shuffled BP (GVSBP) algorithms respectively partition the check and variable nodes of the code graph into groups to perform group-by-group message-passing decoding. This paper proposes new techniques to improve three key elements of a GHSBP decoding algorithm, namely, the grouping method, the decoding schedule and the log-likelihood updating formulae. The (check nodes) grouping method and decoding schedule optimize certain design criterion. The new normalized min-sum updating formula with a self-adjustable correction (scaling) factor offers better nonlinear approximation. Numerical performance of new GHSBP algorithms that include part or all three new techniques indicate that the combination of the proposed grouping and decoding schedule yields a faster convergence rate and our modified min-sum algorithm gives performance superior to that of the conventional min-sum and normalized min-sum algorithm and is very close to that of the sum-product algorithm.
    Information Theory, 2009. ISIT 2009. IEEE International Symposium on; 08/2009
  • Chang-Ming Lee, Yu T. Su
    [Show abstract] [Hide abstract]
    ABSTRACT: Although various measurements have indicated that mobile satellite channels are not memoryless, most related coded system performance analysis assumes perfect interleaving is in place so that the effect of channel memory can be completely ignored. This paper presents a systematic method to accurately and efficiently predict the performance of errors-and-erasures or errors-only decoders for block-coded systems in general mobile satellite channels. Numerical results are provided to validate our analytic results. Copyright © 2008 John Wiley & Sons, Ltd.
    International Journal of Satellite Communications and Networking 05/2008; 26:251-267. · 0.54 Impact Factor
  • Chang-Ming Lee, Y.T. Su, Li-Der Jeng
    [Show abstract] [Hide abstract]
    ABSTRACT: Most investigations on the effect of channel memory on the performance of block codes use a two-state Gilbert-Elliott (GE) model to describe the channel behavior. As there are circumstances that the channel of concern can not be properly described by the GE model, there are some recent works on coded performance that characterize the channel behavior by a general finite-state Markov chain. This letter presents a new efficient systematic approach to analyze the performance of block codes in such a hidden Markov channel (HMC). An application example is given to predict codeword error probability performance of an RS-coded system in a channel with memory. Numerical results are also provided to validate our analytic results.
    IEEE Transactions on Communications 02/2008; · 1.75 Impact Factor
  • Chang-Ming Lee, Y.T. Su
    [Show abstract] [Hide abstract]
    ABSTRACT: Most investigation on the performance of block codes assume perfect interleaving and memoryless channels that introduce only random errors. Some authors have investigated the effect of finite interleaving size on the decoder performance, using a two-state Gilbert-Elliott (GE) model to characterize the channel effect. However, there are circumstances that the burst-error channel of concern can not be properly described by a two-state GE model. This paper extends earlier analysis to investigate the performance of block codes in an environment that can be modeled as an arbitrary finite-state Markov chain
    Vehicular Technology Conference, 2001. VTC 2001 Spring. IEEE VTS 53rd; 02/2001

Publication Stats

4 Citations
3.96 Total Impact Points

Institutions

  • 2001–2009
    • National Chiao Tung University
      • Institute of Communications Engineering
      Hsin-chu-hsien, Taiwan, Taiwan