Alexandru-Corneliu Olteanu

Enabling Mobile Devices for Home Automation Using ZigBee

Home automation systems are collections of interconnected devices for controlling various functions within a house, such as light control, heating, air conditioning, etc. Mobile devices are ideal in providing a user interface in a home automation system, due to their portability and their wide range of capabilities. They can communicate with a home automation network through an Internet gateway, but cannot directly communicate with devices in the network, as these devices usually implement low power communication protocols, such as ZigBee. We investigate several methods to equip an Android device with a dongle capable of ZigBee communication. We propose a scalable architecture, with three abstraction layers, that scales over multiple communication channels, such as the TCP channel, for communication with the gateway, and the USB channel, for direct communication with devices through the dongle. We test the application with two client devices running Android 4.0 and a mock home automation network consisting of a couple of ZigBee devices and a PC as gateway. We estimate the energy consumption of WiFi transfers over several typical use cases and we conclude that using ZigBee can prove beneficial in some cases, both in terms of functionality and performance.

Towards a workload model for online social applications: ICPE 2013 work-in-progress paper

Popular online social applications hosted by social platforms serve, each, millions of interconnected users. Understanding the workloads of these applications is key in improving the management of their performance and costs. In this work, we analyse traces gathered over a period of thirty-one months for hundreds of Facebook applications. We characterize the popularity of applications, which describes how applications attract users, and the evolution pattern, which describes how the number of users changes over the lifetime of an application. We further model both application popularity and evolution, and validate our model statistically, by fitting five probability distributions to empirical data for each of the model variables. Among the results, we find that most applications reach their maximum number of users within a third of their lifetime, and that the lognormal distribution provides the best fit for the popularity distribution.

New Bounds of a Measure in Information Theory

Shannon Entropy, for discrete-valued random variables, plays an important roles in information theory, with applicability in cryptography and communication theory. The purpose of this paper is to present a new bound for the Shannon Entropy. For this we first present a refinement of Jensens inequality.

Energy-efficient user interaction with an off-grid building

This paper describes the design of energy-efficient wide spectrum mechanisms and protocols to capture context information and employ actuation to close the feedback loop. The project described in this article focuses on harvesting energy from the environment through as many ways as possible, and efficiently using the harvested energy in off-grid buildings, dynamically adapting the consumption to currently available energy levels. The main energy sources to be used for harvesting are: solar energy, wind energy, wasted wireless communication energy and hydro energy. Through its web and Android interfaces, the project offers functionalities such as analyzing energy harvesting efficiency, monitoring building-wide energy consumption, setting up profiles and managing consumers individually.

On using Grid and distributed computing for mobile applications

Mobile devices become more and more powerful with each generation and, from a performance point of view, they are rapidly approaching modern computers and laptops. Both user requirements and recent research efforts lead to solutions that allow this new category of computers to be included in a distributed computing environment. First, we discuss some of the key challenges of integrating mobile devices into distributed computing systems. Second, we survey current frameworks and mechanisms for this kind of integration. Third, we discuss per-device and per-application performance analysis. Fourth, we provide a case study on two mobile applications.

Measuring performance and energy consumption when offloading from mobile devices

Mobile devices are becoming more and more popular and at the same time more powerful and power-hungry. Therefore, they represent the best example of systems that would benefit from lowering processing expectations by the use of offloading, because of the continuous lowering battery life and increasing Internet speed. This paper aims to help in discovering the best method of moving an algorithm, or a part of an application, to a more capable system. We will go through finding the performance metrics that describe an application, methods of measuring and the possible ways of using them.