5,636 research outputs found
The capacity region of broadcast channels with intersymbol interference and colored Gaussian noise
We derive the capacity region for a broadcast channel with intersymbol interference (ISI) and colored Gaussian noise under an input power constraint. The region is obtained by first defining a similar channel model, the circular broadcast channel, which can be decomposed into a set of parallel degraded broadcast channels. The capacity region for parallel degraded broadcast channels is known. We then show that the capacity region of the original broadcast channel equals that of the circular broadcast channel in the limit of infinite block length, and we obtain an explicit formula for the resulting capacity region. The coding strategy used to achieve each point on the convex hull of the capacity region uses superposition coding on some or all of the parallel channels and dedicated transmission on the others. The optimal power allocation for any point in the capacity region is obtained via a multilevel water-filling. We derive this optimal power allocation and the resulting capacity region for several broadcast channel models
Classical capacity of bosonic broadcast communication and a new minimum output entropy conjecture
Previous work on the classical information capacities of bosonic channels has
established the capacity of the single-user pure-loss channel, bounded the
capacity of the single-user thermal-noise channel, and bounded the capacity
region of the multiple-access channel. The latter is a multi-user scenario in
which several transmitters seek to simultaneously and independently communicate
to a single receiver. We study the capacity region of the bosonic broadcast
channel, in which a single transmitter seeks to simultaneously and
independently communicate to two different receivers. It is known that the
tightest available lower bound on the capacity of the single-user thermal-noise
channel is that channel's capacity if, as conjectured, the minimum von Neumann
entropy at the output of a bosonic channel with additive thermal noise occurs
for coherent-state inputs. Evidence in support of this minimum output entropy
conjecture has been accumulated, but a rigorous proof has not been obtained. In
this paper, we propose a new minimum output entropy conjecture that, if proved
to be correct, will establish that the capacity region of the bosonic broadcast
channel equals the inner bound achieved using a coherent-state encoding and
optimum detection. We provide some evidence that supports this new conjecture,
but again a full proof is not available.Comment: 13 pages, 7 figure
Stability of Scheduled Message Communication over Degraded Broadcast Channels
We consider scheduled message communication over a discrete memoryless
degraded broadcast channel. The framework we consider here models both the
random message arrivals and the subsequent reliable communication by suitably
combining techniques from queueing theory and information theory. The channel
from the transmitter to each of the receivers is quasi-static, flat, and with
independent fades across the receivers. Requests for message transmissions are
assumed to arrive according to an i.i.d. arrival process. Then, (i) we derive
an outer bound to the region of message arrival vectors achievable by the class
of stationary scheduling policies, (ii) we show for any message arrival vector
that satisfies the outerbound, that there exists a stationary
``state-independent'' policy that results in a stable system for the
corresponding message arrival process, and (iii) under two asymptotic regimes,
we show that the stability region of nat arrival rate vectors has
information-theoretic capacity region interpretation.Comment: 5 pages, Submitted to 2006 International Symposium on Information
Theor
New lower bounds to the output entropy of multi-mode quantum Gaussian channels
We prove that quantum thermal Gaussian input states minimize the output
entropy of the multi-mode quantum Gaussian attenuators and amplifiers that are
entanglement breaking and of the multi-mode quantum Gaussian phase
contravariant channels among all the input states with a given entropy. This is
the first time that this property is proven for a multi-mode channel without
restrictions on the input states. A striking consequence of this result is a
new lower bound on the output entropy of all the multi-mode quantum Gaussian
attenuators and amplifiers in terms of the input entropy. We apply this bound
to determine new upper bounds to the communication rates in two different
scenarios. The first is classical communication to two receivers with the
quantum degraded Gaussian broadcast channel. The second is the simultaneous
classical communication, quantum communication and entanglement generation or
the simultaneous public classical communication, private classical
communication and quantum key distribution with the Gaussian quantum-limited
attenuator
The Arbitrarily Varying Broadcast Channel with Degraded Message Sets with Causal Side Information at the Encoder
In this work, we study the arbitrarily varying broadcast channel (AVBC), when
state information is available at the transmitter in a causal manner. We
establish inner and outer bounds on both the random code capacity region and
the deterministic code capacity region with degraded message sets. The capacity
region is then determined for a class of channels satisfying a condition on the
mutual informations between the strategy variables and the channel outputs. As
an example, we consider the arbitrarily varying binary symmetric broadcast
channel with correlated noises. We show cases where the condition holds, hence
the capacity region is determined, and other cases where there is a gap between
the bounds.Comment: arXiv admin note: substantial text overlap with arXiv:1701.0334
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