A new upper bound on ε-capacity

Michael L. Honig*, Prakash Narayan

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


Summary form only given. Suppose that two outputs of a linear, time-invariant channel are distinguishable at the receiver if and only if they are separated in L2 norm by ε. The inputs to the channel are assumed to be power limited and are nonzero only on the finite time interval [0, T]. Let Nmax(T, ε) be the maximum number of distinguishable outputs for given T, ε > 0. The ε-capacity of the channel, Cε, is defined as the limit, as T → ∞, of log2[Nmax(T, ε)]/T b/s. It has been shown that the noise spectral density that minimizes Shannon capacity, CS, is proportional to the power spectral density of the input. It has also been shown that the resulting upper bound on Cε is less than or equal to the Shannon capacity of a channel consisting of the original channel plus an additive noise source (not necessarily Gaussian) with variance ε2/4, but otherwise having arbitrary statistics. Numerical results have been obtained for models of subscriber loop channels, showing that the new upper bound is significantly better than an upper bound derived previously by Root.

Original languageEnglish (US)
Title of host publication1990 IEEE Int Symp Inf Theor
PublisherPubl by IEEE
Number of pages1
StatePublished - Dec 1 1990
Event1990 IEEE International Symposium on Information Theory - San Diego, CA, USA
Duration: Jan 14 1990Jan 19 1990


Other1990 IEEE International Symposium on Information Theory
CitySan Diego, CA, USA

ASJC Scopus subject areas

  • Engineering(all)


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