QoS improvement in TCP/IP-based wireless sensor networks using cross-layer optimization

Dissertação de Mestrado, Engenharia Informática, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015

Anytime information processing based on fuzzy and neural network models

In modern measurement and control systems, the available time and resources are often not only limited, but could change during the operation of the system. In these cases, the so-called anytime algorithms could be used advantageously. While diflerent soft computing methods are wide-spreadly used in system modeling, their usability in these cases are limited.

IP/optical integration in access network infrastructures: key issues on resource provisioning

This thesis contributes to the advancement of Fiber-Wireless (FiWi) access technologies, through the development of algorithms for resource allocation and energy efficient routing. FiWi access networks use both optical and wireless/cellular technologies to provide high bandwidth and ubiquity, required by users and current high demanding services. FiWi access technologies are divided in two parts. In one of the parts, fiber is brought from the central office to near the users, while in the other part wireless routers or base stations take over and provide Internet access to users. Many technologies can be used at both the optical and wireless parts, which lead to different integration and optimization problems to be solved. In this thesis, the focus will be on FiWi access networks that use a passive optical network at the optical section and a wireless mesh network at the wireless section. In such networks, two important aspects that influence network performance are: allocation of resources and traffic routing throughout the mesh section. In this thesis, both problems are addressed. A fair bandwidth allocation algorithm is developed, which provides fairness in terms of bandwidth and in terms of experienced delays among all users. As for routing, an energy efficient routing algorithm is proposed that optimizes sleeping and productive periods throughout the wireless and optical sections. To develop the stated algorithms, game theory and networks formation theory were used. These are powerful mathematical tools that can be used to solve problems involving agents with conflicting interests. Since, usually, these tools are not common knowledge, a brief survey on game theory and network formation theory is provided to explain the concepts that are used throughout the thesis. As such, this thesis also serves as a showcase on the use of game theory and network formation theory to develop new algorithms.

Intervention for organizational innovation: a case study

This article is intended to report an intervention in a SME of the IT sector, aiming at an organizational change process towards a greater proactivity of employees. The presentation of the case includes the diagnosis, intervention, and the beginning of the implementation of innovation projects, based on an adapted model of third generation large-group organizational change methods. In addition to the steps followed, small-world analysis techniques were used, with the intention of determining the existing communication networks; also, a content analysis of collected success stories was made, in order to suggest strong points for a future organizational culture. The results clarified the desirable characteristics of an intervention method with large groups, adapted to Portuguese companies, and effective in organizational innovation project design. The analysis of the success stories helped to determine the strengths of an orientation for the future, while the use of measures of small-world networks allowed us to analyze the existing informal organization. Although this study does not include the completion of the projects, due to difficulties in the company, it can provide a solid basis for application in future interventions.