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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
- M. Tomlinson. “New automatic equalizer employing modulo
arithmetic”,
Electronic Letters, vol. 7, pp. 138-139, March 1971.
- H. Kobayashi, “Application of probabilistic decoding
to digital magnetic
recording systems,” IBM Journal of Research and Development,
vol. 15,
pp. 65-74, Jan. 1971.
- J. T. Aslanis, S. Kasturia, et. al., “Vector coding for
partial response
channels”, IEEE Military Communications Conference, pp.
667-671, Oct.
1988, .
- 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.
- 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.
- N. Blitvic, L. Zheng, V. Stojanovic, "Low-complexity
Pattern-eliminating Codes for ISI-limited Channels," journal
publication in preparation.
- N. Blitvic, "Channel Coding for High-speed
Links", S.M. thesis, MIT, 2007.
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