2 research outputs found
On the Capacity of the Discrete Memoryless Broadcast Channel with Feedback
A coding scheme for the discrete memoryless broadcast channel with
{noiseless, noisy, generalized} feedback is proposed, and the associated
achievable region derived. The scheme is based on a block-Markov strategy
combining the Marton scheme and a lossy version of the Gray-Wyner scheme with
side-information. In each block the transmitter sends fresh data and update
information that allows the receivers to improve the channel outputs observed
in the previous block. For a generalization of Dueck's broadcast channel our
scheme achieves the noiseless-feedback capacity, which is strictly larger than
the no-feedback capacity. For a generalization of Blackwell's channel and when
the feedback is noiseless our new scheme achieves rate points that are outside
the no-feedback capacity region. It follows by a simple continuity argument
that for both these channels and when the feedback noise is sufficiently low,
our scheme improves on the no-feedback capacity even when the feedback is
noisy.Comment: Accepted to the IEEE Transactions on Information Theor
Coding Schemes and Asymptotic Capacity of the Gaussian Broadcast and Interference Channels with Feedback
A coding scheme is proposed for the memoryless Gaussian broadcast channel
with correlated noises and feedback. For all noise correlations other than -1,
the gap between the sum-rate the scheme achieves and the full-cooperation bound
vanishes as the signal-to-noise ratio tends to infinity. When the correlation
coefficient is -1, the gains afforded by feedback are unbounded and the prelog
is doubled. When the correlation coefficient is +1 we demonstrate a dichotomy:
If the noise variances are equal, then feedback is useless, and otherwise,
feedback affords unbounded rate gains and doubles the prelog. The unbounded
feedback gains, however, require perfect (noiseless) feedback. When the
feedback links are noisy the feedback gains are bounded, unless the feedback
noise decays to zero sufficiently fast with the signal-to-noise ratio.
Extensions to more receivers are also discussed as is the memoryless Gaussian
interference channel with feedback.Comment: 18 page