241 research outputs found
Secret-key Agreement with Channel State Information at the Transmitter
We study the capacity of secret-key agreement over a wiretap channel with
state parameters. The transmitter communicates to the legitimate receiver and
the eavesdropper over a discrete memoryless wiretap channel with a memoryless
state sequence. The transmitter and the legitimate receiver generate a shared
secret key, that remains secret from the eavesdropper. No public discussion
channel is available. The state sequence is known noncausally to the
transmitter. We derive lower and upper bounds on the secret-key capacity. The
lower bound involves constructing a common state reconstruction sequence at the
legitimate terminals and binning the set of reconstruction sequences to obtain
the secret-key. For the special case of Gaussian channels with additive
interference (secret-keys from dirty paper channel) our bounds differ by 0.5
bit/symbol and coincide in the high signal-to-noise-ratio and high
interference-to-noise-ratio regimes. For the case when the legitimate receiver
is also revealed the state sequence, we establish that our lower bound achieves
the the secret-key capacity. In addition, for this special case, we also
propose another scheme that attains the capacity and requires only causal side
information at the transmitter and the receiver.Comment: 10 Pages, Submitted to IEEE Transactions on Information Forensics and
Security, Special Issue on Using the Physical Layer for Securing the Next
Generation of Communication System
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
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