12,535 research outputs found
Optimal Coding Schemes for the Three-Receiver AWGN Broadcast Channel with Receiver Message Side Information
This paper investigates the capacity region of the three-receiver AWGN
broadcast channel where the receivers (i) have private-message requests and
(ii) may know some of the messages requested by other receivers as side
information. We first classify all 64 possible side information configurations
into eight groups, each consisting of eight members. We next construct
transmission schemes, and derive new inner and outer bounds for the groups.
This establishes the capacity region for 52 out of 64 possible side information
configurations. For six groups (i.e., groups 1, 2, 3, 5, 6, and 8 in our
terminology), we establish the capacity region for all their members, and show
that it tightens both the best known inner and outer bounds. For group 4, our
inner and outer bounds tighten the best known inner bound and/or outer bound
for all the group members. Moreover, our bounds coincide at certain regions,
which can be characterized by two thresholds. For group 7, our inner and outer
bounds coincide for four members, thereby establishing the capacity region. For
the remaining four members, our bounds tighten both the best known inner and
outer bounds.Comment: Authors' final version (to appear in IEEE Transactions on Information
Theory
A Graph-based Framework for Transmission of Correlated Sources over Broadcast Channels
In this paper we consider the communication problem that involves
transmission of correlated sources over broadcast channels. We consider a
graph-based framework for this information transmission problem. The system
involves a source coding module and a channel coding module. In the source
coding module, the sources are efficiently mapped into a nearly semi-regular
bipartite graph, and in the channel coding module, the edges of this graph are
reliably transmitted over a broadcast channel. We consider nearly semi-regular
bipartite graphs as discrete interface between source coding and channel coding
in this multiterminal setting. We provide an information-theoretic
characterization of (1) the rate of exponential growth (as a function of the
number of channel uses) of the size of the bipartite graphs whose edges can be
reliably transmitted over a broadcast channel and (2) the rate of exponential
growth (as a function of the number of source samples) of the size of the
bipartite graphs which can reliably represent a pair of correlated sources to
be transmitted over a broadcast channel.Comment: 36 pages, 9 figure
Coding Schemes for a Class of Receiver Message Side Information in AWGN Broadcast Channels
This paper considers the three-receiver AWGN broadcast channel where the
receivers (i) have private-message requests and (ii) know some of the messages
requested by other receivers as side information. For this setup, all possible
side information configurations have been recently classified into eight groups
and the capacity of the channel has been established for six groups (Asadi et
al., ISIT 2014). We propose inner and outer bounds for the two remaining
groups, groups 4 and 7. A distinguishing feature of these two groups is that
the weakest receiver knows the requested message of the strongest receiver as
side information while the in-between receiver does not. For group 4, the inner
and outer bounds coincide at certain regions. For group 7, the inner and outer
bounds coincide, thereby establishing the capacity, for four members out of all
eight members of the group; for the remaining four members, the proposed bounds
reduce the gap between the best known inner and outer bounds.Comment: accepted and to be presented at the 2014 IEEE Information Theory
Workshop (ITW
Secrecy Capacity of a Class of Broadcast Channels with an Eavesdropper
We study the security of communication between a single transmitter and
multiple receivers in a broadcast channel in the presence of an eavesdropper.
We consider several special classes of channels. As the first model, we
consider the degraded multi-receiver wiretap channel where the legitimate
receivers exhibit a degradedness order while the eavesdropper is more noisy
with respect to all legitimate receivers. We establish the secrecy capacity
region of this channel model. Secondly, we consider the parallel multi-receiver
wiretap channel with a less noisiness order in each sub-channel, where this
order is not necessarily the same for all sub-channels. We establish the common
message secrecy capacity and sum secrecy capacity of this channel. Thirdly, we
study a special class of degraded parallel multi-receiver wiretap channels and
provide a stronger result. In particular, we study the case with two
sub-channels two users and one eavesdropper, where there is a degradedness
order in each sub-channel such that in the first (resp. second) sub-channel the
second (resp. first) receiver is degraded with respect to the first (resp.
second) receiver, while the eavesdropper is degraded with respect to both
legitimate receivers in both sub-channels. We determine the secrecy capacity
region of this channel. Finally, we focus on a variant of this previous channel
model where the transmitter can use only one of the sub-channels at any time.
We characterize the secrecy capacity region of this channel as well.Comment: Submitted to EURASIP Journal on Wireless Communications and
Networking (Special Issue on Wireless Physical Layer Security
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