8,151 research outputs found
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
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
Joint Network and Gelfand-Pinsker Coding for 3-Receiver Gaussian Broadcast Channels with Receiver Message Side Information
The problem of characterizing the capacity region for Gaussian broadcast
channels with receiver message side information appears difficult and remains
open for N >= 3 receivers. This paper proposes a joint network and
Gelfand-Pinsker coding method for 3-receiver cases. Using the method, we
establish a unified inner bound on the capacity region of 3-receiver Gaussian
broadcast channels under general message side information configuration. The
achievability proof of the inner bound uses an idea of joint interference
cancelation, where interference is canceled by using both dirty-paper coding at
the encoder and successive decoding at some of the decoders. We show that the
inner bound is larger than that achieved by state of the art coding schemes. An
outer bound is also established and shown to be tight in 46 out of all 64
possible cases.Comment: Author's final version (presented at the 2014 IEEE International
Symposium on Information Theory [ISIT 2014]
Joint Coding and Scheduling Optimization in Wireless Systems with Varying Delay Sensitivities
Throughput and per-packet delay can present strong trade-offs that are
important in the cases of delay sensitive applications.We investigate such
trade-offs using a random linear network coding scheme for one or more
receivers in single hop wireless packet erasure broadcast channels. We capture
the delay sensitivities across different types of network applications using a
class of delay metrics based on the norms of packet arrival times. With these
delay metrics, we establish a unified framework to characterize the rate and
delay requirements of applications and optimize system parameters. In the
single receiver case, we demonstrate the trade-off between average packet
delay, which we view as the inverse of throughput, and maximum ordered
inter-arrival delay for various system parameters. For a single broadcast
channel with multiple receivers having different delay constraints and feedback
delays, we jointly optimize the coding parameters and time-division scheduling
parameters at the transmitters. We formulate the optimization problem as a
Generalized Geometric Program (GGP). This approach allows the transmitters to
adjust adaptively the coding and scheduling parameters for efficient allocation
of network resources under varying delay constraints. In the case where the
receivers are served by multiple non-interfering wireless broadcast channels,
the same optimization problem is formulated as a Signomial Program, which is
NP-hard in general. We provide approximation methods using successive
formulation of geometric programs and show the convergence of approximations.Comment: 9 pages, 10 figure
The Capacity of Three-Receiver AWGN Broadcast Channels with Receiver Message Side Information
This paper investigates the capacity region of three-receiver AWGN broadcast
channels where the receivers (i) have private-message requests and (ii) know
the messages requested by some other receivers as side information. We classify
these channels based on their side information into eight groups, and construct
different transmission schemes for the groups. For six groups, we characterize
the capacity region, and show that it improves both the best known inner and
outer bounds. For the remaining two groups, we improve the best known inner
bound by using side information during channel decoding at the receivers.Comment: This is an extended version of the same-titled paper submitted to
IEEE International Symposium on Information Theory (ISIT) 201
Inner and Outer Bounds for the Gaussian Cognitive Interference Channel and New Capacity Results
The capacity of the Gaussian cognitive interference channel, a variation of
the classical two-user interference channel where one of the transmitters
(referred to as cognitive) has knowledge of both messages, is known in several
parameter regimes but remains unknown in general. In this paper we provide a
comparative overview of this channel model as we proceed through our
contributions: we present a new outer bound based on the idea of a broadcast
channel with degraded message sets, and another series of outer bounds obtained
by transforming the cognitive channel into channels with known capacity. We
specialize the largest known inner bound derived for the discrete memoryless
channel to the Gaussian noise channel and present several simplified schemes
evaluated for Gaussian inputs in closed form which we use to prove a number of
results. These include a new set of capacity results for the a) "primary
decodes cognitive" regime, a subset of the "strong interference" regime that is
not included in the "very strong interference" regime for which capacity was
known, and for the b) "S-channel" in which the primary transmitter does not
interfere with the cognitive receiver. Next, for a general Gaussian cognitive
interference channel, we determine the capacity to within one bit/s/Hz and to
within a factor two regardless of channel parameters, thus establishing rate
performance guarantees at high and low SNR, respectively. We also show how
different simplified transmission schemes achieve a constant gap between inner
and outer bound for specific channels. Finally, we numerically evaluate and
compare the various simplified achievable rate regions and outer bounds in
parameter regimes where capacity is unknown, leading to further insight on the
capacity region of the Gaussian cognitive interference channel.Comment: submitted to IEEE transaction of Information Theor
Filter and nested-lattice code design for fading MIMO channels with side-information
Linear-assignment Gel'fand-Pinsker coding (LA-GPC) is a coding technique for
channels with interference known only at the transmitter, where the known
interference is treated as side-information (SI). As a special case of LA-GPC,
dirty paper coding has been shown to be able to achieve the optimal
interference-free rate for interference channels with perfect channel state
information at the transmitter (CSIT). In the cases where only the channel
distribution information at the transmitter (CDIT) is available, LA-GPC also
has good (sometimes optimal) performance in a variety of fast and slow fading
SI channels. In this paper, we design the filters in nested-lattice based
coding to make it achieve the same rate performance as LA-GPC in multiple-input
multiple-output (MIMO) channels. Compared with the random Gaussian codebooks
used in previous works, our resultant coding schemes have an algebraic
structure and can be implemented in practical systems. A simulation in a
slow-fading channel is also provided, and near interference-free error
performance is obtained. The proposed coding schemes can serve as the
fundamental building blocks to achieve the promised rate performance of MIMO
Gaussian broadcast channels with CDIT or perfect CSITComment: submitted to IEEE Transactions on Communications, Feb, 200
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