9,655 research outputs found
Asymptotically Exact Approximations for the Symmetric Difference of Generalized Marcum-Q Functions
(c) 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works. DOI: 10.1109/TVT.2014.2337263In this paper, we derive two simple and asymptotically exact approximations for the function defined as ΔQm(a, b) =Δ Qm(a, b) - Qm(b, a). The generalized Marcum Q-function Qm(a, b) appears in many scenarios in communications in this particular form and is referred to as the symmetric difference of generalized Marcum Q-functions or the difference of generalized Marcum Q-functions with reversed arguments. We show that the symmetric difference of Marcum Q-functions can be expressed in terms of a single Gaussian Q-function for large and even moderate values of the arguments a and b. A second approximation for ΔQm(a, b) is also given in terms of the exponential function. We illustrate the applicability of these new approximations in different scenarios: 1) statistical characterization of Hoyt fading; 2) performance analysis of communication systems; 3) level crossing statistics of a sampled Rayleigh envelope; and 4) asymptotic approximation of the Rice Ie-function.Universidad de Málaga. Campus de Excelencia Internacional. AndalucÃa Tech
Fiscal Policy in an Imperfectly Competitive Dynamic Small Open Economy
In this paper we develop a general model of an imperfectly competitive small open economy. There is a traded and non-traded sector, whose outputs are combined in order to produce a single final good that can be either consumed or invested. We make general assumptions about preferences and technology, and analyse the impact of fiscal policy on the economy. We find that the fiscal mutiplier is between zero and one, and provide sufficient conditions for it to be increasing in the degree of imperfect competition. We also are able to compare the multiplier under free-entry and with a fixed number of firms, the speed of convergence to equilibrium and welfare. A simple graphical representation of the model is developed.imperfect competition, open economy, fiscal policy.
Composite Fading Models based on Inverse Gamma Shadowing: Theory and Validation
We introduce a general approach to characterize composite fading models based
on inverse gamma (IG) shadowing. We first determine to what extent the IG
distribution is an adequate choice for modeling shadow fading, by means of a
comprehensive test with field measurements and other distributions
conventionally used for this purpose. Then, we prove that the probability
density function and cumulative distribution function of any IG-based composite
fading model are directly expressed in terms of a Laplace-domain statistic of
the underlying fast fading model and, in some relevant cases, as a mixture of
wellknown state-of-the-art distributions. Also, exact and asymptotic
expressions for the outage probability are provided, which are valid for any
choice of baseline fading distribution. Finally, we exemplify our approach by
presenting several application examples for IG-based composite fading models,
for which their statistical characterization is directly obtained in a simple
form.Comment: This work has been submitted to the IEEE for publication. Copyright
may be transferred without notice, after which this version may no longer be
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On human motion prediction using recurrent neural networks
Human motion modelling is a classical problem at the intersection of graphics
and computer vision, with applications spanning human-computer interaction,
motion synthesis, and motion prediction for virtual and augmented reality.
Following the success of deep learning methods in several computer vision
tasks, recent work has focused on using deep recurrent neural networks (RNNs)
to model human motion, with the goal of learning time-dependent representations
that perform tasks such as short-term motion prediction and long-term human
motion synthesis. We examine recent work, with a focus on the evaluation
methodologies commonly used in the literature, and show that, surprisingly,
state-of-the-art performance can be achieved by a simple baseline that does not
attempt to model motion at all. We investigate this result, and analyze recent
RNN methods by looking at the architectures, loss functions, and training
procedures used in state-of-the-art approaches. We propose three changes to the
standard RNN models typically used for human motion, which result in a simple
and scalable RNN architecture that obtains state-of-the-art performance on
human motion prediction.Comment: Accepted at CVPR 1
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