Delivering the PPP promise in Greece: Current situation and lessons learned from the international experience

Public-Private Partnerships (PPP) constitute an alternative method of procuring infrastructure projects. They include the cooperation of the public and private sectors for the provision of assets and services. The idea behind this kind of partnerships is old (France in the 19th century), however, in modern times it was introduced in the UK (1992) under the term Private Finance Iniative (PFI). Since then, and after 15 years of experience and evolution, many countries around the globe have adopted PPPs for projects and services in numerous public sectors, that include: transport, health, education, waste treatment, prisons, defence. In the light of these events, Greece has decided recently (2005) to launch a PPP program with a new legislation, in order to promote PPPs in the Greek market. Until now, only 3 transport projects (Attiki Odos, Rio-Antirio Bridge, International Airport of Athens) were procured as PPPs in Greece, however the "steps" of the Greek economy, during the last 15 years, were towards the participation of private funds in the operation of the state. Moreover, the contribution of the European Union with the Community Support Frameworks (CSF I,II,III 1989-2006) was, and still is, fundamental for the increase of public spending. Thus, we can conclude that the conditions for the development of PPPs, at this specific time, are more than propitious. This report will attempt to evaluate this effort of the Greek state, by examining the history and the present of PPPs in Greece and by using guidelines from the international experience and practice. This provides a basis for future research to examine the success or failure of this method, after the first series of such projects are complete

State-of-the-art on Virtualization and Software Defined Networking for Efficient Resource Allocation on Multi-tenant 5G Networks

Global data traffic explosion is expected to set stringent requirements for next generation networks in the next decades. Besides, very low latencies will have to be guaranteed for enabling new delay critical services. However, current Software Defined Networking (SDN) solutions have limitations in terms of separating both data and control planes among tenants/operators, and the capability to adapt to new or changing requirements. Moreover, some virtualization schemes do not ensure isolation of resources and do not guarantee bandwidth across the entities. While some others fail to provide flexibility to the slices to customize the resource allocation across the users. Therefore, novel SDN and virtualization techniques should be implemented to realize the upcoming 5G network that will facilitate at least efficient resource allocation and multi-tenancy among the plethora of different requirements

SDN and Virtualization Solutions for the Internet of Things: A Survey

The imminent arrival of the Internet of Things (IoT), which consists of a vast number of devices with heterogeneous characteristics, means that future networks need a new architecture to accommodate the expected increase in data generation. Software defined networking (SDN) and network virtualization (NV) are two technologies that promise to cost-effectively provide the scale and versatility necessary for IoT services. In this paper, we survey the state of the art on the application of SDN and NV to IoT. To the best of our knowledge, we are the first to provide a comprehensive description of every possible IoT implementation aspect for the two technologies. We start by outlining the ways of combining SDN and NV. Subsequently, we present how the two technologies can be used in the mobile and cellular context, with emphasis on forthcoming 5G networks. Afterward, we move to the study of wireless sensor networks, arguably the current foremost example of an IoT network. Finally, we review some general SDN-NV-enabled IoT architectures, along with real-life deployments and use-cases. We conclude by giving directions for future research on this topic.Network Architectures and Service

A comprehensive and systematic review of the network virtualization techniques in the IoT

nternet of Things (IoT) as one of the last technology in the network domain is an environment of associated physical objects that are reachable through the Internet. Virtualization as the primary technology of IoT has a significant role in its popularization. The visualization strategies have a great impact on the IoT, but, as far as we know, there is not a comprehensive and systematic study in this field. Also, there is no systematic and complete way to discuss and analyze the related strategies. Henceforth, a systematic survey of virtualization techniques is presented in this paper. Different parameters based on the examination of the prevailing methods are considered in three main categorizations. Furthermore, the benefits and weaknesses connected with selected techniques have been discussed, and the significant issues of these techniques are addressed to improve the more efficient virtualization technique for the future