Past Seminars 2012-2013


Winter '12 / Spring '13


The seminars listed below were organized by Dr. M. Karaliopoulos and Prof. I. Stavrakakis and took place periodically in the Department of Informatics and Telecommunications, University of Athens. Their scope extended over various research topics in the area of computer and telecommunication networks.




Title : Enabling ISP-CDN Collaboration

Speaker: Dr. Georgios Smaragdakis,  Senior Researcher, Deutsche Telekom Labs & TU Berlin

Room: E

Time: 13.00


Abstract: Today, a large fraction of Internet traffic is originated by Content Delivery Networks (CDNs). To cope with increasing demand for content, CDNs have deployed massively distributed infrastructures. These deployments pose challenges for CDNs as they have to dynamically map end-users to appropriate servers without being fully aware of the network conditions within an Internet Service Provider (ISP) or the end-user location. On the other hand, ISPs struggle to cope with rapid traffic shifts caused by the dynamic server selection policies of the CDNs.

The challenges that CDNs and ISPs face separately can be turned into an opportunity for collaboration. We argue that it is sufficient for CDNs and  ISPs to coordinate only in server selection, not routing, in order to perform traffic engineering. To this end, we propose Content-aware Traffic Engineering (CaTE), which dynamically adapts server selection for content hosted by CDNs using ISP recommendations on small time scales. CaTE relies on the observation that by selecting an appropriate server among those available to deliver the content, the path of the traffic in the network can be influenced in a desired way. We present the design and implementation of a prototype to realize CaTE, and show how CDNs and ISPs can jointly take advantage of the already deployed and potentially available distributed hosting infrastructures, path diversity, and ISP detailed view of the network status without revealing sensitive operational information. By relying on traces from a large European ISP and the largest commercial CDN, we show that CaTE allows CDNs to enhance the end-user experience while enabling an ISP to achieve several traffic engineering goals.

You can find more in our project site.

This is a joint work with Ingmar Poese, Benjamin Frank, Anja Feldmann (TU Berlin) and Bruce Maggs (Duke University/Akamai Technologies).


Bio: Georgios Smaragdakis is a Senior Researcher at Deutsche Telekom Laboratories and the Technical University of Berlin, Germany. He received the Ph.D. degree in computer science from Boston University, the Diploma in electronic and computer engineering from the Technical University of Crete, and he interned at Telefonica Research. His research interests include the measurement, performance analysis, and optimization of content distribution systems and overlay networks with main applications in service deployment, server selection, distributed replications and caching, ISP-Application collaboration, and overlay network creation and maintenance. Dr. Smaragdakis received the ACM IMC 2011 best paper award for his work on web content cartography.




Title : PHAROS: enabling a Software-defined (SDN) and cross-layer optimized reconfigurable converged core optical network

Speaker: Prof. Cesar Santivanez (Electrical Engineering Department,  Pontificia Universidad Catolica del Peru)

Room: A 56

Time: 14.00



Software defined networking (SDN) is an emerging architecture for software-based, flexible, and agile network control using an abstracted model of the network.  By utilizing a powerful abstracted network model with enough information to capture network devices’ properties and interdependencies, virtual separation of network resources can be achieved, as well as vertical control (joint optimization) across all the network levels (from service to resource management). The result will be not only a more efficient use of resources, but in the enabling of network operators to easily and quickly specify and install new network services without replacing existing devices or re-wiring existing inter-device connections. Most of the community efforts with SDN/OpenFlow to date have focused on data centers, access networks, and the like. With the notable exception of Google – who has implemented an SDN WAN to interconnect its data centers – no significant effort has been made to bring the SDN promise to core networks. This is understandable since at this early stage SDN/OpenFlow lacks many of the important features required to support a carrier-grade backbone: scalability, reliability, security, etc. In this talk we present PHAROS (Petabit Highly-Agile Robust Optical System), a system providing cross-layer optimization of a SDN core network.


PHAROS, originally funded under the DARPA CORONET program provides architecture, protocols and algorithms for traffic engineering, resource management and signaling solutions for highly-agile, large-capacity core optical networks.  PHAROS main goals were rapid configuration (less than 2 seconds), guaranteed data flow protection to up to 3 simultaneous failures, high stability (including graceful degradation under excessive load), and high degree of security/fault-tolerance in a multi-technology, multi-vendor, and multi-domain environment. Key to achieving these goals was PHAROS creation of abstract representations for all levels of the network. The representations extend down to an abstract network model of the essential contention structure of a node, and extend upward to address successive (virtual) levels of functionality across the entire network. Thanks to these multilevel topology abstractions PHAROS was able to achieve global multi-dimensional optimization over the fundamental dimensions of network management: network extent, technology levels, route protection, and timescales. Abstraction allows a given request to be optimized across the network, simultaneously trading off costs of resources within individual network levels as well as the costs of transit between levels (such as the optical-electrical boundary). Resources of all levels can be considered, including wavelengths, timeslots, grooming ports, and IP capacity. With this uniform approach, common to all levels of resource representation and allocation, PHAROS accurately exploits the capabilities of all network elements, while remaining independent of the switching technology or vendor particularities. Another key enabler was PHAROS unitary approach that combines the best features of centralized and distributed approaches. Long term planning and coordination of resource usage (i.e., “Decision”) were undertaken by a central entity, while the actual switching elements’ configuration and quick reaction to failures (“action”) were undertaken by a distributed network of control elements, following the central entity guidelines (“playbooks”). PHAROS “centralized decision” guaranteed stability and predictable dynamics, while PHAROS “distributed action” achieved quick response to failures.

Bio: Dr. Cesar Santivanez is a professor at the Electrical Engineering Department of the Pontificia Universidad Catolica del Peru, where he is the head of the Advanced Networks Research Lab. Until very recently, he was a Network Scientist in the Network Research group at Raytheon BBN Technologies, where over the past decade he made significant contributions to the field of mobile ad hoc networking (MANET). Among Cesar's many contributions to the field are the development of the theory of MANET routing scalability, the first scalable routing protocol (HSLS), and the characterization of the transport capacity for dynamic spectrum access (DSA) cognitive networks. Cesar has been a key person in several DARPA contracts including DARPA neXt Generation (XG), DARPA CORONET. As part of the latter program, Cesar has applied his expertise on routing on highly dynamic environments to the design of architecture and algorithms for highly efficient resource assignment for reconfigurable optical networks. Cesar has over twenty scholarly publications, was a Fulbright scholar, and received the best student paper award for his paper in the fifth international workshop in Multimedia Communications ( MoMuc' 98). He holds an MS and PhD in EE from Northeastern University





Title : Intelen, Inc: a successful case of transforming Greek applied research to a world-class product

Speakers: Vassilis Nikolopoulos PhD,  Konstantinos Staikos MSc OCP

Room: Ε (ground floor)

Time: 14.30


Abstract: Intelen is a market leader and innovator in Smart Building Energy Analytics. It obtains real time energy use data from buildings (down to 1-2 second intervals) and provides real time advanced data analytics using a web based interface and specific cloud-based algorithms. Intelen uses proprietary technology to connect to buildings and is not dependent on the presence or type of utility smart meter installed. It then uses game mechanics principles to engage users in energy save initiatives and achieve a sustained reduction of energy use of 25-30% on average.
Intelen is the result of four years (2006 - 2010) applied research @ the Multimedia Technology Laboratory of NTUA (ECE dept) that was transformed into a world-class product portfolio. Intelen’s global market is the billion smart grid market and the combination of software, the social web 2.0, data mining technologies and IT methods for energy efficiency analytics in big buildings (also called the “Soft Grid”). Intelen has filed so far two Greek patents (OBI) and two US patent applications to USPTO.
The presentation will have two main parts: in the 1st part, Dr. Ing. V. Nikolopoulos will present the basic applied research theory that Intelen is using, including data mining algorithms, the RKM algorithm and some insights on game mechanics, social energy networks and knowledge data fusion theory, applied to the energy domain. Also, some basic entrepreneurship concepts and how we can transform research findings to a product that solves a society/market problem
In the 2nd part, Mr. Konstantinos Staikos, MSc (OCP) will present Intelen’s core technology and technical/software background on data analytics and general cloud architectures (ie. IPv6, IoT, etc). The complexity of combining real-time meter data, interoperability, streaming information, security, computational complexity and decision theory is rather difficult to reduce and manage. Intelen’s approach produces a very scalable and efficient technology model, capable of analyzing and correlating huge amounts of data in real-time, by applying in-house advanced algorithms for data analytics.


Vassilis Nikolopoulos, PhD: Vassilis is an active entrepreneur, innovator and passionate with technology futurology and trend forecasting. He is the CEO and co-founder of Intelen, Inc, a New York based startup, in the domain of smart grid big data applications and energy analytics/gamification, which recently completed two seed investment rounds (~$600K) and is currently under high growth. From 2005 to 2010, he worked on technical trend forecasting methodologies and innovation management procedures, focusing on the Big Data problems applied to Utilities and the Energy Sector (Smart Grids). He has many awards and global recognitions with his start-up, in top innovation and entrepreneurship contests (Red herring global, Kouros Entrepreneurship prize, SVASE Silicon Valley Launch, OECD best eco-innovation model) and was voted as the best new entry researcher in Greece in 2007. He is a valedictorian Electrical Engineer from Dundee University, Scotland. He also holds a Master and Diploma in Control theory from Imperial College London, specializations in Marketing and Entrepreneurship from LSE, Engineering majors in Applied Maths and Theoretical informatics (+ French classes preparatoires, Maths Physique MP) from the Ecole Polytechnique of Paris and finished his Engineering PhD at NTUA in Knowledge Engineering applied on Smart grids.

Konstantinos Staikos, MSc OCP: Multinational certified Senior IT Architect with over 10 years experience in the IT industry. CTO & co-founder of Intelen, a New York based startup, in the domain of smart grid big data applications and energy analytics/gamification, which recently completed two seed investment rounds (~$600K) and is currently under high growth. Many awards and global recognitions achieved with Intelen, in top innovation and entrepreneurship contests (Red herring global, SVASE Silicon Valley Launch, Siemens global smartgrid innovation award, OECD best eco-innovation model). He has extensive experience in managing and coordinating IT projects and engineering teams in building complex enterprise software systems. Portfolio includes a broad line of successful EU Projects from a position of Technical Manager. Konstantinos holds a B.S in Chemical Engineering from National Technical University of Athens (NTUA) and a M.S in Software Engineering from Technical University in Munich (TUM). Certified in several IT (Oracle, Sun, ISTQB etc) and Project Management (PMI PMP& ACP) certifications programs.





Title : The Neighbourhood Game : From Behavioural Economics to Urban Planning

Speaker: Panayotis Antoniadis (ETH Zurich )

Room: A56

Time: 15.00


Abstract: The rapid advances of information and communication technologies (or ICTs) and the mass online participation have increased the expectations for the long awaited visions of e-participation and e-democracy. However, there are still many challenges that need to be addressed related to privacy, data ownership and control, and various types of digital divides. Perhaps the most fundamental requirement is the need for information exchange between parties that do not necessarily share common interests, education, and cultural backgrounds. To achieve this, ICT could significantly help if designers understand in depth the way technology affects behaviour in the evolving hybrid (virtual and physical) space of modern cities, and communities are empowered to choose the tools that are most suitable for their environment and configure them according to their own values and objectives. In this presentation I will introduce a research framework connecting two relatively remote until today disciplines, namely behavioural economics and urban planning, through the mediation of computer science.
More specifically, I will describe a long-term social learning process evolved around a configurable ICT framework, the NetHood Toolkit, which will support a wide variety of hybrid interactions between people in physical proximity. The definition of a specific set of information sharing games with various configuration options can then form the basis for a real life experimentation process with potential benefits both for understanding human behaviour and for reaching important social objectives.

Bio : Panayotis Antoniadis is a lecturer and senior researcher at ETH Zurich. His main research contributions to date are in the economic modelling and incentive mechanisms for peer-to-peer systems and in distributed scheduling algorithms for high-speed switches.He is currently pursuing a cross-disciplinary research agenda on the role of social software and wireless networks for the design of sustainable hybrid neighborhood communities (project nethood).
Panayotis received his Ph.D. degree from the Athens University of Economics and Business in 2006, and until 2012 he was a post-doc
researcher at UPMC Sorbonne Universites in Paris.




Title : How to solve a real life problem through a smartphone application: the case of Parking Defenders

Speaker: Kostas Arkadas


Abstract: Parking Defenders is a breakthrough mobile application designed for iPhone, Windows Phone and Android smartphones that intends to transform the nightmare of parking in metropolitan areas to a game. The application addresses two cases, search of on-street parking spots and use of parking lots. The first case leverages the social network element: users can offer their parking spot to the rest of the users (whenever they keeps the Defender role) or find a parking spot for themselves by claiming a spot another user is offering (this time keeping the Seeker part). The application is particularly user friendly even to those who are not addicted to their smartphone. The second case addresses parking lot operators and aims at a more effective management of the parking lot capacity through revenue management techniques. We will discuss the solutions that have been implemented in the two cases and the experience with the application so far.

Bio : Kostas Arkadas is a software engineer who is co-founder of a Greek startup company named Parking Defenders, which has attracted enormous publicity over the last two years in Greek and international media ( The company aims at solving the parking problem and bringing innovation to the management of parking space. As a software engineer he has worked in a wide variety of business applications. He is passionate about mobile technologies and how to build a better future. Kostas has a B.Sc. in Computer Sciences from the University of Athens and was scholar for two years at IPSYP /Athena.