Selected Recent Papers and Simulation Packages: Lei WEI

Hierarchical decoding

  • [1] L. Wei, "Near Optimal Limited Search Decoding: part 2. Convolutional Codes," partly published in [2], pdf file .
    Comments: Partly was published in [2] and partly wasnot published. The unpublished parts are now leading to the IVA papers and Optimal Importance sampling papers. The readers can see how the IVA links to the bootstrap algorithm.

  • [2] Lei Wei, Honghui Qi, "Near-optimal limited-search detection on ISI/CDMA channels and decoding of long convolutional codes," IEEE Trans. Information Theory, Vol.46, July 2000 Page(s): 1459 -1482. pdf file .
    Simulation packages.

    Comments: This paper showed (a) why the M-algorithm can perform optimal for ISI/CDMA channels; (b) how to decode long convolutional codes (with millions and billions of states. Please see imperfectness of Hierarchical decoder + long convolutional codes (CC).. If you know near optimal CC codes with memory length of 50-60, please let me know.

    Iterative Viterbi decoding

  • [3] L. Wei, "Near Shannon Limit Iterative Viterbi Algorithm for Conventional Concatenated Systems," IEEE Trans. Information Theory, submitted, 1999, currently under revision. pdf file (commign soon) .
    Simulation packages to improve Qualcomm system using IVA.
    Simulation packages to improve Qualcomm system using IVA+parity code.
    Simulation packages for 2D parity concatenated codes.


    Comments: In this paper we show (a) how to apply IVA for CRC concatenated codes, CC/BCH concatenated codes and for continuous transmission; (b) why parity concatenated codes can achieve a better performance; (c) for block lengths of from 56 to about 10000 information bits, IVA and parity concatenated codes are within about 1 dB of Sphere packing bounds.

  • [4] Q. Wang and L. Wei, "Graph-Based Iterative Decoding Algorithms for Parity-Concatenated Trellis Codes," IEEE Trans. Information Theory, Volume: 47 Issue: 3 , March 2001 Page(s): 1062 -1074. pdf file .
    Comments: In this paper, we show for a code with many small cycles in its TWL graph modified iterative two-way algorithms (min-sum and sum-product) can achieve near optimal decoding.

  • [5] Qi Wang, Lei Wei and Rodney A. Kennedy, "Iterative Viterbi Decoding, Trellis Shaping and Multilevel Structure for High-Rate Concatenated TCM," IEEE Trans on Communications, accepted provided revision. pdf file .
    Simulation packages.

    Comments: In this paper,we show how to apply IVA for high rate TCM with trellis shaping. It is 1.2 dB away from Shannon limit.

  • [6] Q. Wang and L. Wei, "Iterative Viterbi Algorithm for Concatenated Multi-dimensional TCM," IEEE Trans. on Communications, (submitted Dec 2000), currently under revision. pdf file .
    Comments: We further extend the results in [5] to cover the multi-level TCM case and parallel continuous transmission. It is about 2 dB away from the Shannon Limit. To cover the MD TCM is not as easy as we thought, but it can be done.

  • [7] L. Wei, "Iterative Viterbi Algorithm: A Simple Turbo Decoding Method Using the Viterbi Decoding Hardware," IEEE JSAC wireless series, submitted April, 2001. pdf file .
    Comments: We showed that (a) for many popular conventional serial concatenated codes we can use the VA hardware to form a IVA decoder; (b) the CRC code used in mobile systems (such as Qualcomm and GSM) can play a dual-role: error correcting and error detection.

    Optimal Importance Sampling

  • [8] Y. Wei and L. Wei, "Construction of Fast Recovery Codes Using A New Optimal Importance Sampling Method," IEEE Trans. Information Theory, to appear. pdf file.
    Comments: We showed that (a) how to search for fast recovery codes; (b) how to construct optimal IS method for a transient Markov system.

  • [9] Y. Wei, H.Qi and L. Wei, "Optimal Importance Sampling for Queuing Networks," ACM Trans. Modeling and Computer Simulations. (Submitted Feb. 2001.). pdf file .
    Comments: The optimal IS method has been extended to analyse Queuing networks. It is much better than the LDT method.

    Others

  • [10] L. Wei, Z. Li, M. James and I. Petersen, "A Minimax Robust Decoding Algorithm," IEEE Trans. on Information Theory, May 2000, pp.1158-1167. pdf file .

  • Lei Wei; Jana, R. "Performance bounds for optimum multiuser DS-CDMA systems," IEEE Transactions on Communications, Volume: 47 Issue: 2 , Feb. 1999, Page(s): 185 -190. pdf file .

    [12] Lei Wei; Aulin, T.; Honghui Qi, "On the effect of truncation length on the exact performance of a convolutional code", IEEE Transactions on Information Theory, , Volume: 43 Issue: 5 , Sept. 1997 Page(s): 1678 -1681. pdf file .


    Last modified: June, 2001.