3,506 research outputs found
An Achievable Rate Region for the Broadcast Channel with Feedback
A single-letter achievable rate region is proposed for the two-receiver
discrete memoryless broadcast channel with generalized feedback. The coding
strategy involves block-Markov superposition coding, using Marton's coding
scheme for the broadcast channel without feedback as the starting point. If the
message rates in the Marton scheme are too high to be decoded at the end of a
block, each receiver is left with a list of messages compatible with its
output. Resolution information is sent in the following block to enable each
receiver to resolve its list. The key observation is that the resolution
information of the first receiver is correlated with that of the second. This
correlated information is efficiently transmitted via joint source-channel
coding, using ideas similar to the Han-Costa coding scheme. Using the result,
we obtain an achievable rate region for the stochastically degraded AWGN
broadcast channel with noisy feedback from only one receiver. It is shown that
this region is strictly larger than the no-feedback capacity region.Comment: To appear in IEEE Transactions on Information Theory. Contains
example of AWGN Broadcast Channel with noisy feedbac
Maximum Likelihood Decoder for Index Coded PSK Modulation for Priority Ordered Receivers
Index coded PSK modulation over an AWGN broadcast channel, for a given index
coding problem (ICP) is studied. For a chosen index code and an arbitrary
mapping (of broadcast vectors to PSK signal points), we have derived a decision
rule for the maximum likelihood (ML) decoder. The message error performance of
a receiver at high SNR is characterized by a parameter called PSK Index Coding
Gain (PSK-ICG). The PSK-ICG of a receiver is determined by a metric called
minimum inter-set distance. For a given ICP with an order of priority among the
receivers, and a chosen -PSK constellation we propose an algorithm to find
(index code, mapping) pairs, each of which gives the best performance in terms
of PSK-ICG of the receivers. No other pair of index code (of length with
broadcast vectors) and mapping can give a better PSK-ICG for the highest
priority receiver. Also, given that the highest priority receiver achieves its
best performance, the next highest priority receiver achieves its maximum gain
possible and so on in the specified order or priority.Comment: 9 pages, 6 figures and 2 table
A Unified Scheme for Two-Receiver Broadcast Channels with Receiver Message Side Information
This paper investigates the capacity regions of two-receiver broadcast
channels where each receiver (i) has both common and private-message requests,
and (ii) knows part of the private message requested by the other receiver as
side information. We first propose a transmission scheme and derive an inner
bound for the two-receiver memoryless broadcast channel. We next prove that
this inner bound is tight for the deterministic channel and the more capable
channel, thereby establishing their capacity regions. We show that this inner
bound is also tight for all classes of two-receiver broadcast channels whose
capacity regions were known prior to this work. Our proposed scheme is
consequently a unified capacity-achieving scheme for these classes of broadcast
channels.Comment: accepted and to be presented at the 2015 IEEE International Symposium
on Information Theory (ISIT 2015
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