Variable-length Non-binary Constrained Sequence Codes

  • Author / Creator
    Tu, Xin
  • Block-oriented constrained sequence codes have historically been used in the digital communications and data storage industry. However, we contend that in certain applications, variable-length constrained sequence codes can be better than block codes in terms of efficiency and implementation complexity. A technique to construct capacity-approaching constrained sequence codes with variable-length codewords was recently developed. This construction process can be divided into four parts. First, it is necessary to define a minimal set of prefix-free words whose concatenation satisfies the constraint. Then, sets of instantaneously decodable codewords are constructed by concatenating words from this minimal set through partial extensions of this minimal set. Third, the optimal mapping between variable-length source words and each set of variable-length codewords is determined using normalized geometric Huffman coding. Lastly, the average code rate of each code constructed is evaluated, and the code with highest code rate is selected as the best code. Based on the four steps above, in this thesis we construct new non-binary codes for multilevel magnetic recording, and new balanced codes for transmission systems using quaternary phase shift keying modulation. Our codes have higher code rates (within 98% of capacity) than codes designed through any other construction technique published to date.

  • Subjects / Keywords
  • Graduation date
    Spring 2016
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.