Dimitris Varoutas

Learn More
The paper assesses the market conditions and dynamics, the architectures and the different approaches for deployment of 3G Mobile Virtual Network Operators (MVNOs), in an attempt to address specific advantages and pitfalls. Following the definition of appropriate service sets and tariff structures, and taking into account demand scenarios, a techno-economic(More)
Transferring wireless broadband services across extremely far distances on Earth is usually implemented nowadays either by ground-based or satellite communications. Terrestrial networks require, however, heavy installation and maintenance costs, whereas satellite networks suffer from excessively high power requirements. An alternative but highly challenging(More)
Due to the increasing demand in data rates telecom operators are faced with the question of when to upgrade their access network infrastructure toward fiber-to-the-home (FTTH). In this paper a techno-economic study of fiber-to-the-cabinet/very high bit rate digital subscriber line (FTTC/VDSL) and FTTH deployments is performed. The economics and risks(More)
The use of relays is one of the most promising methods for mitigating impairments of the performance of free-space optical (FSO) systems and extending their limited transmission range. However, several factors contribute to significant link performance degradation. Most severe is the influence of the adverse atmospheric conditions that frequently appear,(More)
The transmission of multiple wireless signals over optical links has attained a great research interest nowadays. In case where optical fibers are difficult to be deployed, or installation cost is prohibited, optical wireless systems provide an efficient alternative means. In this paper, we consider the WiMAX (IEEE802.16) standard and construct a simple but(More)
Article history: Received 29 March 2009 Received in revised form 11 January 2010 Accepted 23 January 2010 Forecasting diffusion of new technologies is usually performed by the means of aggregate diffusion models, which tend to monopolize this area of research and practice, making the alternative approaches, like the Box-Jenkins, less favourable choices due(More)
Non-line-of-sight optical wireless transmission, operated in the unlicensed ultraviolet UV-C band, has been recently suggested as an alternative means of communication. However, due to limited coverage, relayed UV-C networks need to be deployed in order to supply communication services at large distances. In this paper, we consider a serial multi-hop UV-C(More)
The economic perspective of the mobile networks in Europe Dimitris Katsianis (University of Athens , GR), Ilari Welling, Maria Ylönen (NOKIA, FI), Dimitris Varoutas, Thomas Sphicopoulos (University of Athens, GR), Nils Kristian Elnegaard, Borgar T. Olsen (Telenor, NO), Lucien Budry (Swisscom, CH) ∗ National and Kapodistrian University of Athens Department(More)
This paper focuses on the connectivity issues of a non-line-of-sight (NLOS) optical wireless network operating in the ultraviolet UV-C spectral region. NLOS UV-C transmitters have a limited effective coverage and, hence, a dense node distribution is required in order to efficiently cover a large geographical area. Under this assumption, the concept of(More)
As society progressively depends on large-scale telecommunications networks and their connectivity rapidly rises over time, it becomes of vital importance to study their topological features. On the backbone level uncertain disturbances of its constituent parts may affect a sizable proportion of the population, thus this can well explain the recent focus on(More)