Efficient LDPC codes over GF(q) for Lossy data compression

  • Authors:
  • Alfredo Braunstein;Farbod Kayhan;Riccardo Zecchina

  • Affiliations:
  • Politecnico di Torino, Dipartimento di Fisica, Torino, Italy;Politecnico di Torino, Dipartimento di Fisica, Torino, Italy;Politecnico di Torino, Dipartimento di Fisica, Torino, Italy

  • Venue:
  • ISIT'09 Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3
  • Year:
  • 2009

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Abstract

In this paper we consider the lossy compression of a binary symmetric source. We present a scheme that provides a low complexity lossy compressor with near optimal empirical performance. The proposed scheme is based on b-reduced ultrasparse LDPC codes over GF(q). Encoding is performed by the Reinforced Belief Propagation algorithm, a variant of Belief Propagation. The computational complexity at the encoder is O(d .n.q.log2 q), where d is the average degree of the check nodes. For our code ensemble, decoding can be performed iteratively following the inverse steps of the leaf removal algorithm. For a sparse parity-check matrix the number of needed operations is O(n).