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Variable-Rate Capacity-Approaching LDPC Codes for HF Communications

Research output: Contribution in Book/Report/Proceedings - With ISBN/ISSNConference contribution/Paperpeer-review

Publication date07/2006
Host publicationThe 10th Institution of Engineering and Technology International Conference on Ionospheric Radio Systems & Techniques (IRST 2006)
Place of PublicationLondon, UK
PublisherIET Press
Number of pages5
ISBN (Print)0863416594
<mark>Original language</mark>English


The HF propagation channel involves several interrelated phenomena that results in a highly variable medium, which poses a challenge in designing and implementing effective high speed digital communications systems for HF band. The reliability of HF communication is affected by time-varying propagation conditions of HF channel that demands requirement for coding schemes with adaptive protection capabilities, to combat the ever-changing channel conditions and thus improve the reliability and performance of the channel. The novel idea introduced in this paper, proposes a variable forward error correction scheme using capacity-approaching 'low density parity check' codes that enables the switching between LDPC codes of constant length but variable rates (1/4, 1/2, & 9/10) to provide variable-error protection based on the channel condition at any given time. These codes have been simulated over a Rayleigh fading channel and their capacity approaching performance using the sum-product decoding algorithm is shown.