4,277 research outputs found
Noisy Channel-Output Feedback Capacity of the Linear Deterministic Interference Channel
In this paper, the capacity region of the two-user linear deterministic (LD)
interference channel with noisy output feedback (IC-NOF) is fully
characterized. This result allows the identification of several asymmetric
scenarios in which imple- menting channel-output feedback in only one of the
transmitter- receiver pairs is as beneficial as implementing it in both links,
in terms of achievable individual rate and sum-rate improvements w.r.t. the
case without feedback. In other scenarios, the use of channel-output feedback
in any of the transmitter-receiver pairs benefits only one of the two pairs in
terms of achievable individual rate improvements or simply, it turns out to be
useless, i.e., the capacity regions with and without feedback turn out to be
identical even in the full absence of noise in the feedback links.Comment: 5 pages, 9 figures, see proofs in V. Quintero, S. M. Perlaza, and
J.-M. Gorce, "Noisy channel-output feedback capacity of the linear
deterministic interference channel," INRIA, Tech. Rep. 456, Jan. 2015. This
was submitted and accepted in IEEE ITW 201
Capacity of All Nine Models of Channel Output Feedback for the Two-user Interference Channel
In this paper, we study the impact of different channel output feedback
architectures on the capacity of the two-user interference channel. For a
two-user interference channel, a feedback link can exist between receivers and
transmitters in 9 canonical architectures (see Fig. 2), ranging from only one
feedback link to four feedback links. We derive the exact capacity region for
the symmetric deterministic interference channel and the constant-gap capacity
region for the symmetric Gaussian interference channel for all of the 9
architectures. We show that for a linear deterministic symmetric interference
channel, in the weak interference regime, all models of feedback, except the
one, which has only one of the receivers feeding back to its own transmitter,
have the identical capacity region. When only one of the receivers feeds back
to its own transmitter, the capacity region is a strict subset of the capacity
region of the rest of the feedback models in the weak interference regime.
However, the sum-capacity of all feedback models is identical in the weak
interference regime. Moreover, in the strong interference regime all models of
feedback with at least one of the receivers feeding back to its own transmitter
have the identical sum-capacity. For the Gaussian interference channel, the
results of the linear deterministic model follow, where capacity is replaced
with approximate capacity.Comment: submitted to IEEE Transactions on Information Theory, results
improved by deriving capacity region of all 9 canonical feedback models in
two-user interference channe
Perfect Output Feedback in the Two-User Decentralized Interference Channel
In this paper, the -Nash equilibrium (-NE) region of the two-user
Gaussian interference channel (IC) with perfect output feedback is approximated
to within bit/s/Hz and arbitrarily close to bit/s/Hz. The
relevance of the -NE region is that it provides the set of rate-pairs
that are achievable and stable in the IC when both transmitter-receiver pairs
autonomously tune their own transmit-receive configurations seeking an
-optimal individual transmission rate. Therefore, any rate tuple outside
the -NE region is not stable as there always exists one link able to
increase by at least bits/s/Hz its own transmission rate by updating its
own transmit-receive configuration. The main insights that arise from this work
are: The -NE region achieved with feedback is larger than or equal
to the -NE region without feedback. More importantly, for each rate pair
achievable at an -NE without feedback, there exists at least one rate
pair achievable at an -NE with feedback that is weakly Pareto superior.
There always exists an -NE transmit-receive configuration that
achieves a rate pair that is at most bit/s/Hz per user away from the outer
bound of the capacity region.Comment: Revised version (Aug. 2015
On Two-Pair Two-Way Relay Channel with an Intermittently Available Relay
When multiple users share the same resource for physical layer cooperation
such as relay terminals in their vicinities, this shared resource may not be
always available for every user, and it is critical for transmitting terminals
to know whether other users have access to that common resource in order to
better utilize it. Failing to learn this critical piece of information may
cause severe issues in the design of such cooperative systems. In this paper,
we address this problem by investigating a two-pair two-way relay channel with
an intermittently available relay. In the model, each pair of users need to
exchange their messages within their own pair via the shared relay. The shared
relay, however, is only intermittently available for the users to access. The
accessing activities of different pairs of users are governed by independent
Bernoulli random processes. Our main contribution is the characterization of
the capacity region to within a bounded gap in a symmetric setting, for both
delayed and instantaneous state information at transmitters. An interesting
observation is that the bottleneck for information flow is the quality of state
information (delayed or instantaneous) available at the relay, not those at the
end users. To the best of our knowledge, our work is the first result regarding
how the shared intermittent relay should cooperate with multiple pairs of users
in such a two-way cooperative network.Comment: extended version of ISIT 2015 pape
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