Cognitive radios exploit observed information about channel activity to
improve communications, spectrum utilization, and network performance.
A building block of a network with cognitive radios is a two-sender,
two-receiver interference channel where one encoder has side information
about the other encoder's message. We present different operating regimes
for this system that depend on channel conditions. We show that a variety
of encoding techniques - rate-splitting, Gel'fand-Pinsker coding, and
superposition coding - improve rates over non-cognitive schemes, and that
the best encoding technique depends on the operating regime.
Several achievable rate regions are evaluated for Gaussian channels.
The results indicate that cognitive techniques may impact spectrum
licensing rules in frequency bands with primary and secondary users. The
techniques may also be applied to cognitive and non-cognitive radios
operating in unlicensed bands. Broadly speaking, our results encourage the
view of a network in which cognition enables cooperation, and where
all users are cognitive and use available side information for relaying.
This is a joint work with Andrea Goldsmith, Gerhard Kramer and Shlomo Shamai (Shitz).
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