Ourania I. Markaki

Packet-switched network selection with the highest QoS in 4G networks

The evolution of telecommunications during the last decades has been enormous and as a result, nowadays, people find themselves before the challenge of 4G networks. Due to the fact that the latter constitute an environment of heterogeneous networks, their integration in terms of the Quality of Service (QoS) offered is of crucial importance. In general, the topic of this paper is to integrate the parameters that define QoS. Specifically, the main scope of this paper is the development of a process to evaluate three packet-switched networks (UMTS, WLAN and GPRS) in reference to the QoS offered and finally, the selection of the network that offers the highest standard for QoS. In order to achieve the above goal, there has been an attempt to distinguish the most important QoS indicators that characterize packet-switched networks and a few processes have been developed in order to either estimate the contribution of each parameter to the total QoS, or identify the weak points of a network. Apparently, each of these processes approaches the term of QoS in a different way and gives results of different usefulness.

Application of Fuzzy AHP and ELECTRE to Network Selection

In a heterogeneous wireless network environment services are ubiquitously delivered over multiple wireless access technologies. Ranking of the alternatives and selection of the most efficient and suitable access network to meet the QoS requirements of a specific service, as these are defined by the user, constitutes thus an important issue. Decisions on which network to connect to are however difficult to be reached, since multiple factors of different relative importance have to be taken into consideration. This paper addresses this difficulty by adopting Multi Attribute Decision Making (MADM) methods. Fuzzy AHP, a MADM method, is initially applied to determine the weights of certain Quality of Service indicators that act as the criteria impacting the decision process. The fuzzy extension of the method, and consequently the use of fuzzy numbers, is adopted in order to incorporate the existence of fuzziness as a result of subjective evaluations. Afterwards, ELECTRE, a ranking MADM method, is applied to rank the alternatives, in this case wireless networks, based on their overall performance.

Congestion Avoidance Control through Non-cooperative Games between Customers and Service Providers

Congestion avoidance control refers to controlling the load of the network by restricting the admission of new user’s sessions and resolving the unwanted overload situations. Admission control and Load control constitute key mechanisms regarding Radio Resource Management. As the wireless world is moving towards heterogeneous wireless networks, these types of control are facing more challenges, since efficiency and fairness are required. Game theory provides an appropriate framework for formulating fair and efficient congestion avoidance control problems. In this paper we formulate a non-cooperative game between service providers and customers. On the one hand, the service providers wish to maximize their revenue, but on the other hand, the users wish to maximize the quality of service received, keeping at the same time the expenses as low as possible. Therefore a balance has to be established among these contradictory demands. Our effort also concentrates in the proper modeling of the user’s level of satisfaction, so as to provide a logical decision-taking framework. The proposed scheme is then tested using the ns2 simulator. Results show that both parties can benefit from this mechanism.

A Unified Network Selection Framework Using Principal Component Analysis and Multi Attribute Decision Making

Services are ubiquitously delivered over multiple wireless access technologies in a heterogeneous wireless network environment. A significant issue is the ranking of the alternative access networks and the selection of the most efficient and suitable one in order to meet the Quality of Service (QoS) requirements of a specific service, as these are defined by the user. With this way, the user receives enhanced Quality of Experience. However, decisions on which network to connect are usually difficult to be reached, since multiple factors of different importance have to be taken into consideration. The subject of the paper is the introduction of a novel unified network selection framework. A framework for defining decision criteria weights relying on the variance of network measurements is also provided. For this purpose, Principal Component Analysis and Analytic Hierarchy Process are deployed so as to unravel the patterns in data and retrieve parameter weights through pair wise comparisons respectively. The framework addresses the final network selection by the employment of Multi Attribute Decision Making methods and by using certain QoS indicators acting as figures of merit which influence the decision process. Finally, the proposed scheme is tested through extended simulations and a discussion over its performance is made. Some useful conclusions are drawn.

Benefits and Risks in Dynamic Manufacturing Networks

More and more manufacturing enterprises realize that, by operating as single enterprises in traditional supply chains, they cannot cope with the challenges of the modern demanding environment, and that they need to adopt new and innovative strategies in order to remain competitive. The establishment of Dynamic Manufacturing Networks (DMNs) brings together various innovations, such as just-in-time delivery, flexible manufacturing, organizational streamlining, and total quality, and emerges therefore as an advanced reaction of collaborating enterprises to the constantly changing business environment and its characteristics. This paper aims to expose the benefits and risks involved in such networks, and create thereby the foundation for elaborating further on the key factors that could be utilized for attracting organizations and enterprises into embracing the vision of DMNs, supporting thus not only industrial organizations and practitioners interested in implementing such solutions, but also scholars and researchers who study these new forms of business.

Evaluation of the Impact and Adoption of E-government Services in the Balkans

Governments around the world are embracing the digital revolution to enhance services for their citizens. However, the development of quality e-services and delivery systems that are efficient and effective is only one aspect of e-government.

Digital technology and innovation trajectories in the Mediterranean region

Weak macroeconomic conditions mean admittedly that government spending on Information and Communication Technologies (ICTs) is reduced and consequently that ICT-related policies are scrutinized for their necessity, efficiency and impact on growth. At the same time, such conditions bring into the spotlight and set priority to measures targeting the ICT sector and promoting ICT-based innovation as a means of pursuing economic recovery. The 2008 financial crisis affected severely several parts of the world and particularly the Mediterranean region, where, even today, several years after the start of this economic turmoil in Europe, finding an effective response to mitigating the consequences of recession is still pertinent. Building on previous literature that recognizes ICT-based innovation as a crisis mitigation enabler, this paper propels discussion on the association among ICT- and innovation-oriented indicators and the economic crisis context in four Mediterranean countries, namely Spain, Greece, Italy and Cyprus. In this respect, it leverages a set of open and credible indicators of both technological and economic character and attempts to reflect on the effects of the crisis on ICT or conversely seen the potential of the latter to enable the affected countries to come out of the crisis.

Assessing Governmental Policies' Impact through Prosperity Indicators and Open Data

The aim of this paper is to provide an overview of (the theory and practice of) prosperity indicators for assessing the impact of governmental policies and the data sources associated to their calculation, touching also on the broad theme of Open Data which opens up new horizons for the calculation and exploitation of Social Indicators. Following a quick overview of the basics of prosperity indicators, their basic methodological principles and their typology, a presentation of the Policy Compass project approach and the description of its pilot application in St. Petersburg are provided, which are tackling the above mentioned issue with the provision of a powerful ICT platform.

Personalization Mechanisms for Content Indexing, Search, Retrieval and Presentation in a Multimedia Search Engine

Interest on multimedia content analysis, archival, retrieval and delivery is steadily increasing. This interest emanates from the digital media explosion that we are witnessing. Among others, the growth of multimedia content is compounding the need for more effective methods for searching such information. The automated web search engines that are currently used rely only on text descriptions and as a result provide matches of poor quality in case of multimedia content. On the other hand, search engines that utilize low-level descriptors to support content-based retrieval focus on algorithmic approaches and not on the provision of services oriented at efficiently covering the users needs. The scope of this paper is to present a personalized web-based multimedia search engine implemented in the Java programming language. The proposed system combines the characteristics of the current search engines as well as new innovative features which guarantee a) reduced response time b) improved search results c) adaptation to each users preferences d) easy handling of multimedia content e) interactive multimedia searching f) support of context-based user groups. The analytic description of the systems mechanisms and features renders clear how the proposed search engine adapts its functionality to each users individuality.

Digital Transformation: Is Public Sector Following the Enterprise 2.0 Paradigm?

Among the most important, and certainly most promising, trends of the last decade is this of digitization. Organizations, and mainly businesses, of various profiles invest lots of money and effort in order to digitize processes, products and offerings. The paper at hand aims to investigate whether the same applies to the public sector as well. A pair of carefully selected indicators (namely Digital Adoption Index and Digital Evolution Index) are applied to a selected sample of countries (namely Germany, Greece, Russia, Spain and United Kingdom) in order for interesting results to be derived.