tailieunhanh - Báo cáo hóa học: "Research Article Differentially Encoded LDPC Codes—Part I: Special Case of Product Accumulate Codes"

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 Differentially Encoded LDPC Codes—Part I: Special Case of Product Accumulate Codes | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2008 Article ID 824673 14 pages doi 2008 824673 Research Article Differentially Encoded LDPC Codes Part I Special Case of Product Accumulate Codes Jing Li Tiffany Electrical and Computer Engineering Lehigh University Bethlehem PA 18015 USA Correspondence should be addressed to Jing Li Tiffany jingli@ Received 19 November 2007 Accepted 6 March 2008 Recommended by Yonghui Li Part I of a two-part series investigates product accumulate codes a special class of differentially-encoded low density parity check DE-LDPC codes with high performance and low complexity on flat Rayleigh fading channels. In the coherent detection case Divsalar s simple bounds and iterative thresholds using density evolution are computed to quantify the code performance at finite and infinite lengths respectively. In the noncoherent detection case a simple iterative differential detection and decoding IDDD receiver is proposed and shown to be robust for different Doppler shifts. Extrinsic information transfer EXIT charts reveal that with pilot symbol assisted differential detection the widespread practice of inserting pilot symbols to terminate the trellis actually incurs a loss in capacity and a more efficient way is to separate pilots from the trellis. Through analysis and simulations it is shown that PA codes perform very well with both coherent and noncoherent detections. The more general case of DE-LDPC codes where the LDPC part may take arbitrary degree profiles is studied in Part II Li 2008. Copyright 2008 Jing Li Tiffany . 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 The discovery of turbo codes and the rediscovery of low-density parity-check LDPC codes have renewed the research frontier of .