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Báo cáo hóa học: " Construction of Rate-Compatible LDPC Codes Utilizing Information Shortening and Parity Puncturing"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Construction of Rate-Compatible LDPC Codes Utilizing Information Shortening and Parity Puncturing | EURASIP Journal on Wireless Communications and Networking 2005 5 789-795 2005 T. Tian and C. R. Jones Construction of Rate-Compatible LDPC Codes Utilizing Information Shortening and Parity Puncturing Tao Tian QUALCOMM Incorporated San Diego CA 92121 USA Email ttian@qualcomm.com Christopher R. Jones Jet Propulsion Laboratory California Institute of Technology NASA CA 91109 USA Email crjones@jpl.nasa.gov Received 27 January 2005 Revised 25 July 2005 Recommended for Publication by Tongtong Li This paper proposes a method for constructing rate-compatible low-density parity-check LDPC codes. The construction considers the problem of optimizing a family of rate-compatible degree distributions as well as the placement of bipartite graph edges. A hybrid approach that combines information shortening and parity puncturing is proposed. Local graph conditioning techniques for the suppression of error floors are also included in the construction methodology. Keywords and phrases rate compatibility shortened codes punctured codes irregular low-density parity-check codes density evolution extrinsic message degree. 1. INTRODUCTION Complexity-constrained systems that undergo variations in link budget may benefit from the adoption of a ratecompatible family of codes. Code symbol puncturing has been widely used to construct rate-compatible convolutional codes 1 parallel concatenated codes 2 3 and serially concatenated codes 4 . Techniques for implementing rate compatibility in the context of LDPC coding have primarily pursued parity puncturing 5 6 . In particular a density evolution model for an additive white Gaussian noise AWGN channel with puncturing was developed by Ha et al. 5 . The model was used to find asymptotically optimal puncturing fractions in a density evolution sense for each variable node degree of a mother code distribution to achieve given higher code rates. Li and Narayanan 7 show that puncturing alone is insufficient for the formation of a sequence of .