Integrated Systems Group | Prof. Vladimir Stojanovic
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PATTERN-ELIMINATING CODES FOR ISI-LIMITED CHANNELS

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MARCO Interconnect Focus Center

People

Natasa Blitvic, Professor Lizhong Zheng, Professor Vladimir Stojanovic


Inter-symbol-interference (ISI)-limited channels occur commonly in practice, often as a consequence of hardware power/complexity constraints, which reduce the practical degree of equalization achieved (for example, in high-speed chip-to-chip interconnects). Although a variety of existing communication techniques, such as Tomlinson precoding [1], partial response maximum likelihood (PRML) [2], vector coding [3] or distance-enhancing constraint coding [4] among others, combat the ISI to some degree, their complexity/hardware requirements may not be suitable for all applications.

This work explores the possibility of achieving a performance gain relying only on simplistic encoding and decoding. The result is a class of systematic binary block codes, termed pattern-eliminating codes (PEC), which allow for simple encoding, trivial decoding and provide a performance benefit by improving the minimum decision distance. The regime of interest requires the noise to be relatively small compared to the effect of dominant interfering symbols and occurs for instance in an under-equalized high-speed link. Over most channels, the pattern eliminating codes can also exhibit additional runlength-limiting properties at no additional coding overhead.

The construction of the pattern-eliminating codes and performance results in a typical high-speed link are available in [5-7].

 

References

  1. M. Tomlinson. “New automatic equalizer employing modulo arithmetic”,
    Electronic Letters, vol. 7, pp. 138-139, March 1971.
  2. H. Kobayashi, “Application of probabilistic decoding to digital magnetic
    recording systems,” IBM Journal of Research and Development, vol. 15,
    pp. 65-74, Jan. 1971.
  3. J. T. Aslanis, S. Kasturia, et. al., “Vector coding for partial response
    channels”, IEEE Military Communications Conference, pp. 667-671, Oct.
    1988, .
  4. K. A. Schouhamer Immink, P. H. Siegel, J. K. Wolf, “Codes for Digital
    Recorders,” IEEE Transactions on Information Theory, vol. 44, no. 6,
    October 1998.
  5. N. Blitvic, L. Zheng, V. Stojanovic, "Low-complexity Pattern-eliminating Codes for ISI-limited Channels," to be presented at the IEEE International Conference on Communications, Beijing, China, 19-23 May, 2008.
  6. N. Blitvic, L. Zheng, V. Stojanovic, "Low-complexity Pattern-eliminating Codes for ISI-limited Channels," journal publication in preparation.
  7. N. Blitvic, "Channel Coding for High-speed Links", S.M. thesis, MIT, 2007.
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