tailieunhanh - Báo cáo hóa học: " Research Article LDPC Code Design for Nonuniform Power-Line Channels"

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: Research Article LDPC Code Design for Nonuniform Power-Line Channels | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2007 Article ID 76146 9 pages doi 2007 76146 Research Article LDPC Code Design for Nonuniform Power-Line Channels Ali Sanaei and Masoud Ardakani Department of Electrical and Computer Engineering Faculty of Engineering University of Alberta Edmonton AB Canada T6G 2V4 Received 28 October 2006 Revised 8 March 2007 Accepted 1 May 2007 Recommended by Lutz Lampe We investigate low-density parity-check code design for discrete multitone channels over power lines. Discrete multitone channels are well modeled as nonuniform channels that is different bits experience various channel parameters. We propose a coding system for discrete multitone channels that allows for using a single code over a nonuniform channel. The number of code parameters for the proposed system is much greater than the number of code parameters in conventional channel. Therefore search-based optimization methods are impractical. We first formulate the problem of optimizing the rate of an irregular low-density parity-check code with guaranteed convergence over a general nonuniform channel as an iterative linear programming which is significantly more efficient than search-based methods. Then we use this technique for a typical power-line channel. The methodology of this paper is directly applicable to all decoding algorithms for which a density evolution analysis is possible. Copyright 2007 A. Sanaei and M. Ardakani. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION Discrete multitone DMT modulation is widely used in power-line communications. DMT modulation is almost always used in conjunction with channel coding which is called coded DMT. In the past few years some of the modern coding techniques such as low-density parity-check LDPC .