6,324 research outputs found
On the Nash Equilibria in Decentralized Parallel Interference Channels
In this paper, the 2-dimensional decentralized parallel interference channel
(IC) with 2 transmitter-receiver pairs is modelled as a non-cooperative static
game. Each transmitter is assumed to be a fully rational entity with complete
information on the game, aiming to maximize its own individual spectral
efficiency by tuning its own power allocation (PA) vector. Two scenarios are
analysed. First, we consider that transmitters can split their transmit power
between both dimensions (PA game). Second, we consider that each transmitter is
limited to use only one dimension (channel selection CS game). In the first
scenario, the game might have either one or three NE in pure strategies (PS).
However, two or infinitely many NE in PS might also be observed with zero
probability. In the second scenario, there always exists either one or two NE
in PS. We show that in both games there always exists a non-zero probability of
observing more than one NE. More interestingly, using Monte-Carlo simulations,
we show that the highest and lowest network spectral efficiency at any of the
NE in the CS game are always higher than the ones in the PA.Comment: 6 pages, 4 figures, presented in ICCC Kyoto 201
Noisy Channel-Output Feedback Capacity of the Linear Deterministic Interference Channel
In this paper, the capacity region of the two-user linear deterministic (LD)
interference channel with noisy output feedback (IC-NOF) is fully
characterized. This result allows the identification of several asymmetric
scenarios in which imple- menting channel-output feedback in only one of the
transmitter- receiver pairs is as beneficial as implementing it in both links,
in terms of achievable individual rate and sum-rate improvements w.r.t. the
case without feedback. In other scenarios, the use of channel-output feedback
in any of the transmitter-receiver pairs benefits only one of the two pairs in
terms of achievable individual rate improvements or simply, it turns out to be
useless, i.e., the capacity regions with and without feedback turn out to be
identical even in the full absence of noise in the feedback links.Comment: 5 pages, 9 figures, see proofs in V. Quintero, S. M. Perlaza, and
J.-M. Gorce, "Noisy channel-output feedback capacity of the linear
deterministic interference channel," INRIA, Tech. Rep. 456, Jan. 2015. This
was submitted and accepted in IEEE ITW 201
Consistent 3D Quantum Gravity on Lens Spaces
We study non-perturbative quantization of 3d gravity with positive
cosmological constant (de Sitter space being the prototype vacuum solution,
whose Euclideanization of course gives the three sphere) on the background
topology of lens space, which is a three spheres modulo a discrete group.
Instead of the strategy followed by a recent work \cite{Castro:2011xb}, which
compares results in the second and first order formulations of gravity, we
concentrate on the later solely. We note, as a striking feature, that the
quantization, that relies heavily on the axiomatics of topological quantum
field theory (TQFT) can only be consistently carried by augmenting the
conventional theory by an additional topological term coupled through a
dimensionless parameter. More importantly the introduction of this additional
parameter renders the theory finite.Comment: New section and references added. Accepted in Phys. Rev. D for
publicatio
Quality-Of-Service Provisioning in Decentralized Networks: A Satisfaction Equilibrium Approach
This paper introduces a particular game formulation and its corresponding
notion of equilibrium, namely the satisfaction form (SF) and the satisfaction
equilibrium (SE). A game in SF models the case where players are uniquely
interested in the satisfaction of some individual performance constraints,
instead of individual performance optimization. Under this formulation, the
notion of equilibrium corresponds to the situation where all players can
simultaneously satisfy their individual constraints. The notion of SE, models
the problem of QoS provisioning in decentralized self-configuring networks.
Here, radio devices are satisfied if they are able to provide the requested
QoS. Within this framework, the concept of SE is formalized for both pure and
mixed strategies considering finite sets of players and actions. In both cases,
sufficient conditions for the existence and uniqueness of the SE are presented.
When multiple SE exist, we introduce the idea of effort or cost of satisfaction
and we propose a refinement of the SE, namely the efficient SE (ESE). At the
ESE, all players adopt the action which requires the lowest effort for
satisfaction. A learning method that allows radio devices to achieve a SE in
pure strategies in finite time and requiring only one-bit feedback is also
presented. Finally, a power control game in the interference channel is used to
highlight the advantages of modeling QoS problems following the notion of SE
rather than other equilibrium concepts, e.g., generalized Nash equilibrium.Comment: Article accepted for publication in IEEE Journal on Selected Topics
in Signal Processing, special issue in Game Theory in Signal Processing. 16
pages, 6 figure
Neutral dynamics with environmental noise: age-size statistics and species lifetimes
Neutral dynamics, where taxa are assumed to be demographically equivalent and
their abundance is governed solely by the stochasticity of the underlying
birth-death process, has proved itself as an important minimal model that
accounts for many empirical datasets in genetics and ecology. However, the
restriction of the model to demographic [] noise yields
relatively slow dynamics that appears to be in conflict with both short-term
and long-term characteristics of the observed systems. Here we analyze two of
these problems - age size relationships and species extinction time - in the
framework of a neutral theory with both demographic and environmental
stochasticity. It turns out that environmentally induced variations of the
demographic rates control the long-term dynamics and modify dramatically the
predictions of the neutral theory with demographic noise only, yielding much
better agreement with empirical data. We consider two prototypes of "zero mean"
environmental noise, one which is balanced with regard to the arithmetic
abundance, another balanced in the logarithmic (fitness) space, study their
species lifetime statistics and discuss their relevance to realistic models of
community dynamics
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