13,700 research outputs found
On the Capacity Region of the Deterministic Y-Channel with Common and Private Messages
In multi user Gaussian relay networks, it is desirable to transmit private
information to each user as well as common information to all of them. However,
the capacity region of such networks with both kinds of information is not easy
to characterize. The prior art used simple linear deterministic models in order
to approximate the capacities of these Gaussian networks. This paper discusses
the capacity region of the deterministic Y-channel with private and common
messages. In this channel, each user aims at delivering two private messages to
the other two users in addition to a common message directed towards both of
them. As there is no direct link between the users, all messages must pass
through an intermediate relay. We present outer-bounds on the rate region using
genie aided and cut-set bounds. Then, we develop a greedy scheme to define an
achievable region and show that at a certain number of levels at the relay, our
achievable region coincides with the upper bound. Finally, we argue that these
bounds for this setup are not sufficient to characterize the capacity region.Comment: 4 figures, 7 page
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
Deterministic Capacity of MIMO Relay Networks
The deterministic capacity of a relay network is the capacity of a network
when relays are restricted to transmitting \emph{reliable} information, that
is, (asymptotically) deterministic function of the source message. In this
paper it is shown that the deterministic capacity of a number of MIMO relay
networks can be found in the low power regime where \SNR\to0. This is
accomplished through deriving single letter upper bounds and finding the limit
of these as \SNR\to0. The advantage of this technique is that it overcomes
the difficulty of finding optimum distributions for mutual information.Comment: Submitted to IEEE Transactions on Information Theor
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