5 research outputs found
Paging and Registration in Cellular Networks: Jointly Optimal Policies and an Iterative Algorithm
This paper explores optimization of paging and registration policies in
cellular networks. Motion is modeled as a discrete-time Markov process, and
minimization of the discounted, infinite-horizon average cost is addressed. The
structure of jointly optimal paging and registration policies is investigated
through the use of dynamic programming for partially observed Markov processes.
It is shown that there exist policies with a certain simple form that are
jointly optimal, though the dynamic programming approach does not directly
provide an efficient method to find the policies.
An iterative algorithm for policies with the simple form is proposed and
investigated. The algorithm alternates between paging policy optimization and
registration policy optimization. It finds a pair of individually optimal
policies, but an example is given showing that the policies need not be jointly
optimal. Majorization theory and Riesz's rearrangement inequality are used to
show that jointly optimal paging and registration policies are given for
symmetric or Gaussian random walk models by the nearest-location-first paging
policy and distance threshold registration policies.Comment: 13 pages, submitted to IEEE Trans. Information Theor
Tight Bounds on the R\'enyi Entropy via Majorization with Applications to Guessing and Compression
This paper provides tight bounds on the R\'enyi entropy of a function of a
discrete random variable with a finite number of possible values, where the
considered function is not one-to-one. To that end, a tight lower bound on the
R\'enyi entropy of a discrete random variable with a finite support is derived
as a function of the size of the support, and the ratio of the maximal to
minimal probability masses. This work was inspired by the recently published
paper by Cicalese et al., which is focused on the Shannon entropy, and it
strengthens and generalizes the results of that paper to R\'enyi entropies of
arbitrary positive orders. In view of these generalized bounds and the works by
Arikan and Campbell, non-asymptotic bounds are derived for guessing moments and
lossless data compression of discrete memoryless sources.Comment: The paper was published in the Entropy journal (special issue on
Probabilistic Methods in Information Theory, Hypothesis Testing, and Coding),
vol. 20, no. 12, paper no. 896, November 22, 2018. Online available at
https://www.mdpi.com/1099-4300/20/12/89
A precise bare simulation approach to the minimization of some distances. Foundations
In information theory -- as well as in the adjacent fields of statistics,
machine learning, artificial intelligence, signal processing and pattern
recognition -- many flexibilizations of the omnipresent Kullback-Leibler
information distance (relative entropy) and of the closely related Shannon
entropy have become frequently used tools. To tackle corresponding constrained
minimization (respectively maximization) problems by a newly developed
dimension-free bare (pure) simulation method, is the main goal of this paper.
Almost no assumptions (like convexity) on the set of constraints are needed,
within our discrete setup of arbitrary dimension, and our method is precise
(i.e., converges in the limit). As a side effect, we also derive an innovative
way of constructing new useful distances/divergences. To illustrate the core of
our approach, we present numerous examples. The potential for widespread
applicability is indicated, too; in particular, we deliver many recent
references for uses of the involved distances/divergences and entropies in
various different research fields (which may also serve as an interdisciplinary
interface)
Intelligent home automation security system based on novel logical sensing and behaviour prediction
The thesis, Intelligent Home Automation Security System Based on Novel Logical Sensing and Behavior Prediction, was designed to enhance authentication, authorization and security in smart home devices and services. The work proposes a three prong defensive strategy each of which are analyzed and evaluated separately to drastically improve security. The Device Fingerprinting techniques proposed, not only improves the existing approaches but also identifies the physical device accessing the home cybernetic and mechatronic systems using device specific and browser specific parameters. The Logical Sensing process analyses home inhabitant actions from a logical stand point and develops sophisticated and novel sensing techniques to identify intrusion attempts to a home’s physical and cyber space. Novel Behavior prediction methodology utilizes Bayesian networks to learn normal user behavior which is later compared to distinguish and identify suspicious user behaviors in the home in a timely manner. The logical sensing, behavior prediction and device fingerprinting techniques proposed were successfully tested, evaluated and verified in an actual home cyber physical system. The algorithms and techniques proposed in the thesis can be easily modified and adapted into many practical applications in Industrial Internet of Things, Industry 4.0 and cyber-physical systems.Thesis (PhD)--University of Pretoria, 2017.Electrical, Electronic and Computer EngineeringPhDUnrestricte