6,486 research outputs found
Interference Channel with Intermittent Feedback
We investigate how to exploit intermittent feedback for interference
management. Focusing on the two-user linear deterministic interference channel,
we completely characterize the capacity region. We find that the
characterization only depends on the forward channel parameters and the
marginal probability distribution of each feedback link. The scheme we propose
makes use of block Markov encoding and quantize-map-and-forward at the
transmitters, and backward decoding at the receivers. Matching outer bounds are
derived based on novel genie-aided techniques. As a consequence, the
perfect-feedback capacity can be achieved once the two feedback links are
active with large enough probabilities.Comment: Extended version of the same-titled paper that appears in IEEE
International Symposium on Information Theory (ISIT) 201
A Relay Can Increase Degrees of Freedom in Bursty Interference Networks
We investigate the benefits of relays in multi-user wireless networks with
bursty user traffic, where intermittent data traffic restricts the users to
bursty transmissions. To this end, we study a two-user bursty MIMO Gaussian
interference channel with a relay, where two Bernoulli random states govern the
bursty user traffic. We show that an in-band relay can provide a degrees of
freedom (DoF) gain in this bursty channel. This beneficial role of in-band
relays in the bursty channel is in direct contrast to their role in the
non-bursty channel which is not as significant to provide a DoF gain. More
importantly, we demonstrate that for certain antenna configurations, an in-band
relay can help achieve interference-free performances with increased DoF. We
find the benefits particularly substantial with low data traffic, as the DoF
gain can grow linearly with the number of antennas at the relay. In this work,
we first derive an outer bound from which we obtain a necessary condition for
interference-free DoF performances. Then, we develop a novel scheme that
exploits information of the bursty traffic states to achieve them.Comment: submitted to the IEEE Transactions on Information Theor
Achievable Regions for Interference Channels with Generalized and Intermittent Feedback
In this paper, we first study a two-user interference channel with
generalized feedback. We establish an inner bound on its capacity region. The
coding scheme that we employ for the inner bound is based on an appropriate
combination of Han-Kobayash rate splitting and compress-and-forward at the
senders. Each sender compresses the channel output that is observes using a
compression scheme that is \`a-la Lim et al. noisy network coding and
Avestimeher et al. quantize-map-and-forward. Next, we study an injective
deterministic model in which the senders obtain output feedback only
intermittently. Specializing the coding scheme of the model with generalized
feedback to this scenario, we obtain useful insights onto effective ways of
combining noisy network coding with interference alignment techniques. We also
apply our results to linear deterministic interference channels with
intermittent feedback.Comment: To appear in Proc. of the 2014 IEEE International Symposium on
Information Theory, 6 pages, 2 figure
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
- …