10,045 research outputs found
On the Capacity Region of the Two-user Interference Channel with a Cognitive Relay
This paper considers a variation of the classical two-user interference
channel where the communication of two interfering source-destination pairs is
aided by an additional node that has a priori knowledge of the messages to be
transmitted, which is referred to as the it cognitive relay. For this
Interference Channel with a Cognitive Relay (ICCR) In particular, for the class
of injective semi-deterministic ICCRs, a sum-rate upper bound is derived for
the general memoryless ICCR and further tightened for the Linear Deterministic
Approximation (LDA) of the Gaussian noise channel at high SNR, which disregards
the noise and focuses on the interaction among the users' signals. The capacity
region of the symmetric LDA is completely characterized except for the regime
of moderately weak interference and weak links from the CR to the destinations.
The insights gained from the analysis of the LDA are then translated back to
the symmetric Gaussian noise channel (GICCR). For the symmetric GICCR, an
approximate characterization (to within a constant gap) of the capacity region
is provided for a parameter regime where capacity was previously unknown. The
approximately optimal scheme suggests that message cognition at a relay is
beneficial for interference management as it enables simultaneous over the air
neutralization of the interference at both destinations
On the cognitive interference channel with causal unidirectional destination cooperation
In previous works, the cognitive interference channel with unidirectional destination cooperation has been studied. In this model, the cognitive receiver acts as a relay of the primary user's message, and its operation is assumed to be strictly causal. In this letter, we study the same channel model with a causal rather than a strictly causal relay, i.e., the relay's transmit symbol depends not only on its past but also on its current received symbol. We propose an outer bound for the discrete memoryless channel, which is later used to compute an outer bound for the Gaussian channel. We also propose an achievable scheme based on instantaneous amplify-and-forward relaying that meets the outer bound in the very strong interference regime
Generalized Degrees of Freedom of the Interference Channel with a Signal Cognitive Relay
We study the interference channel with a signal cognitive relay. A signal
cognitive relay knows the transmit signals (but not the messages) of the
sources non-causally, and tries to help them communicating with their
respective destinations. We derive upper bounds and provide achievable schemes
for this channel. These upper and lower bounds are shown to be tight from
generalized degrees of freedom point of view. As a result, a characterization
of the generalized degrees of freedom of the interference channel with a signal
cognitive relay is given.Comment: Results submitted to ISIT 2010, 19 pages, 3 figure
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