Latest News
  • 23 Jun 2016 – Channel 6: New Solar System Internet Technology (Interview)
  • 21 Jun 2016 – New Solar System Internet Technology debuts on ISS - DUTH contribution is acknowledged by NASA
  • 28 Sep 2015 – NASA officially thanks SPICE team for its contribution to the Interplanetary Overlay Network (ION) system
  • 03 Jun 2015 – The kick-off meeting of SENSKIN project was successfully held in Athens, Greece.
  • 26 Feb 2015 – The kick-off meeting of UMOBILE project was successfully held in the premises of the Engineering Department, University College of London, UK.
Vassilis Tsaoussidis

Vassilis Tsaoussidis

Professor, DUTH

Research Affiliate, MIT

Department of Electrical and Computer Engineering

Office 1, Building A,

Panepistimioupolis Kimmeria

Xanthi 67100, Greece

e-mail: vtsaousi (at)

tsaoussi (at)

Tel.: +30 2541079553-554 (sec)

Fax: +30 2541079554


Curriculum Vitae

Vassilis Tsaoussidis was born in Drama, Greece, in November 1966. He holds degrees in Applied Mathematics (Aristotle University, Greece) and Computer Science (Ph.D in Computer Networks Humboldt University, Berlin, Germany). Vassilis returned to Greece to serve the Greek Army and then held a postdoctoral appointment at the Department of Computer Science, Rutgers University, New Brunswick, NJ and faculty appointments at the Computer Science Department of SUNY Stony Brook, NY and at the college of Computer Science of Northeastern University, Boston, MA. He returned to Greece in May 2003 to join the Faculty of the Department of Electrical and Computer Engineering of Democritus University, where he was elected full Professor in 2007. He served as distinguished guest at the Graduate School of Technical University of Berlin in 2005 and he was Visiting Professor at MIT, where he served his sabbatical in 2009 and is a research associate since then.

Vassilis is the Director of "Internetworked Systems Lab", and founder of the first European "Space Internetworking Center - SPICE". The Lab received funding from ESA and FP7 and coordinates large projects (some of which were ranked first in their respective category). The center includes a unique Testbed for Europe, with internetworked nodes in Greece, Germany, Cambridge, MIT and elsewhere; it is appropriate for evaluating Space and Internetworking protocols in challenging environments and includes satellite links, ground station hardware devices, protocols for delay-tolerant networks as well as for tele-metry / tele-command. The testbed has also direct access to Hellas Sat and - through University of Colorado at Boulder - access to the ISS. His team includes 27 engineers and international research associates, many of whom have worked occasionally in NASA JPL during ongoing joint research efforts between NASA and SPICE. Due to its large funding and novel engineering approaches, the Lab received wide attention in local, national and international news (

Vassilis’s research interests lie mainly in transport/network layers including the design and evaluation of energy-saving, real time, delay-tolerant or space protocols as well as the design and evaluation of mechanisms for congestion control, routing, quality of service and reliability. Broadly, his research is associated with internetworking theory and technologies. He is known for his contribution in the study of heterogeneous networks, including

  • wired and wireless infrastructures (e.g., "Open Issues on TCP for Mobile Computing"),
  • real-time properties of internetworked systems (e.g., "TCP-Real: improving real-time capabilities of TCP in heterogeneous networks"),
  • congestion avoidance and control (e.g., "Receiver-oriented congestion control", "The dynamics of responsiveness and smoothness in heterogeneous networks", "Approaches to congestion control in packet networks", "Additive increase, Multiplicative decrease - Fast Convergence (AIMD-FC)", Exploiting the efficiency and fairness potential of AIMD-based congestion avoidance and control")
  • energy efficiency of communication protocols (e.g., "TCP-Probing: Towards an error control schema woth energy and throughput performance gains") and
  • Delay-tolerant networking (e.g. "Deep space transport protocols: A novel Transport scheme for Space DTN’s").

His work received important citations (g-index 29 in "publish or perish"). His research contribution as DUTH coordinator for international projects was more than 5 million euro from European funding agencies during the last 5 years.

Vassilis was/is editor in several well-known journals including IEEE Transactions on Mobile Computing (highest impact factor in IEEE 2009), the Journal of Computer Networks (the first networking journal) the Journal of Wireless Communications and Mobile Computing the Journal of Mobile Multimedia and the International Journal of Parallel, Emergent and Distributed Systems. He is also Editor-in-chief for "The Journal of Internet Engineering". Vassilis edited several special issues on internetworking topics and chaired several conferences.

Vassilis represents ESA (European Space Agency) in the DTN workgroup of the Consultative Committee for Space Data Systems (CCSDS) and was National Representative for FP7 Cooperation - Space. Vassilis received several awards; so far, he has graduated 8 Ph.D students and around 30 Masters. A list of selected, highly-cited publications is appended below (full list can be found at


Research achievements

During the last decade Prof. Vassilis Tsaoussidis contributed to the following fields:

  • Congestion avoidance and control: This topic has dominated networking research during the last decade. A number of systems have been evaluated analytically and experimentally and several algorithms have been proposed. Most significant achievement is the correction of technical flaws of the most widely-used and long-lived algorithm of the Internet, namely, AIMD. Departing from a Ph.D. thesis, AIMD has improved its convergence performance and now operates under a new scheme called AIMD-FC. The algorithm has been incorporated in educational books, operating systems and research papers. Another relevant paper in this category that studies the dynamics of efficiency and fairness as well as of responsiveness and smoothness has been awarded with the runner up award (among 452 submitted papers). Many invited talks and keynotes have been given in the topic, including talks and seminars at MIT, keynotes at IEEE conferences and distinguished lectures at TU Berlin. Professor Tsaoussidis was editor for the oldest and one of the most prestigious journals in this area, namely, The journal of Computer Networks.
  • Wired/Wireless Internet: This constitutes one the major research contributions, given that papers in this category are widely cited. Work here has been focused on the properties of heterogeneous systems and improvements of their aspects, including their energy and throughput performance. The paper "Open issues on TCP for Mobile Computing" was recommended by most groups as a reference paper for the study of such systems. The work on wireless Internet was cited by most top-cited authors in Computer Science and TCP-Probing became one of the most well-known versions of TCP. Professor Tsaoussidis was editor of the most prestigious journal in this research area (IEEE Transactions on Mobile Computing) and founder of Wired/Wireless Internet Communications conference, a conference that was established in 2000, with average acceptance rate around 20% and high reputation. Professor Tsaoussidis chairs the steering committee of this IFIP conference and participated in the board of most important conferences and journals in the field.
  • Delay-tolerant networking: This topic has attracted wide attention recently and was introduced as the new philosophy for the heterogeneous Internet. Prof. Tsaoussidis’s team contributes to the standards and is one the most well-known groups, internationally. The laboratoty of Intenetworks Systems hosts the first and probably richest testbed for delay tolerant networking, with nodes spanning across Europe (Cambridge, ESA/ESOC, Helsinki) and the US (MIT, Colorado).
  • Space Internetworking: Research in this topic resulted in the establishment of the first European Space Internetworking Center in Xanthi. The center aims at unifying Space and traditional networks by incorporating/extending internetworking protocols into Space. This includes the potential to extend Space communications to a 24x7 operation, even in deep space, reduces cost of Space missions and allows for Space data to be better exploited on Earth. The Center was highly ranked for its potential (among top 2% of submitted proposals). In addition, the Center undertook as coordinator the design and implementation of Space Data routers, a proposal that was funded with 2.5 million Euros and was ranked first in Europe in its category. Prof. Tsaoussidis consults ESA as an expert in internetworking and has delivered more than 50 invited talks on the topic, including talks at MIT Aero-Astro, Boston University, NASA JPL, ESA/ESOC, University of Cambridge, University of Helsinki (Aalto), Tampere, Consultative Committee for Space Standards and many other institutions. His group has proposed the Deep Space Transport Protocols and contributed to Internet and Space standards (including internet drafts and Blue/Green books). Discussions about exploiting the commercial potential of proposed protocols are ongoing between DUTH /SPICE and NASA.

In summary, Prof. Tsaoussidis has published over 150 papers and designed several internetworking protocols. His Ph.D. graduates have served as researchers or Assistant Professors in universities worldwide, including University College London, University of Florida, University of Cyprus, University of Hannover etc.


Other research projects

Title: Space Internetworking Center

Acronym: SPICE

Starting Date: 01 Sept 2010

Duration: 36 months

Total Budget: 1.546.072 Euro

EC Contribution: 1.379.014,20 Euro

Funded by FP7-Research Potential, Coordinated by Prof. Vassilis Tsaoussidis, DUTH

The laboratory of Internetworked Systems of the Department of Electrical and Computer Engineering of Democritus University of Thrace, Greece, has made significant contributions to the architectural requirements, objectives standardization and prototyping of future Space Internetworking strategy in Europe and beyond. Space Internetworking has gained momentum in both Space and Internet Communities and enters a phase of wide experimentation, standardization and deployment, binding scientific expertise of diverse communities. We intend to strengthen our research potential and broaden our scientific expertise in major areas covered by Space Internetworking. This includes protocol technology for Space and Earth, mission requirements and design strategies, distributed applications for Space data, mechanisms and algorithms for space data processing, including security issues.

The scheduled activities of this project will result in the unification of three laboratories in a European Center for Space Internetworking (SPICE), capable of consulting significant missions, undertaking important projects such as the unification of space and earth communication and also hosting world-class experts. Therefore, funding of the project will leave a permanent quality stamp in the region through a world-class center of innovation, which will promote science, European competitiveness and certainly will greatly boost the social and economical status of the convergence region of Thrace.

Our scope is to lead the research community towards the most promising directions of research and development in the area of DTN in order to disseminate, create awareness and stimulate exploitation of this knowledge by European Commission, ESA, National Research funding organizations and international standardization bodies, such as IETF and CCSDS. This will be achieved through the mobility of SPICE researchers to cooperating research institutes, the employment of researchers, the organization of panel sessions and workshops, the upgrade of the existing research infrastructure, the organization of regular presentations from high-level scientists etc.


Title: Space-Data Routers

Acronym: SDR

Starting Date: 01 Dec 2010

Duration: 42 months

Total Budget: 2.253.972 Euro

EC Contribution: 1.686.477,70 Euro

Coordinated by DUTH - Principal Investigator: Vassilis Tsaoussidis

FP-7 Project co-funded by European Commission

SPA.2010.2.1-03 Exploitation of science and exploration data

This project has the potential to allow Space Agencies, Academic Institutes and Research Centers to share space-data generated by a single or multiple missions, in a natural, flexible, secure and automated manner. We develop a communication overlay modeled according to thematic context of missions, Ground Segment topological distribution, Agency policies and Application restrictions and requirements. We realize our model through the development of Space-Data Routers: a (Delay-Tolerant Networking) DTN-enabled device that:

  • incorporates the Space Agency administrative instructions and policies for data dissemination and resource utilization, and
  • integrates the DTN protocol stack with application, network and link layer protocols.

We pay particular attention to ESA roadmap for Interplanetary Communications and implement a communication scheme that scales natively with future deployments in Space. In essence, we promote the ultimate objective of most missions, which is to return space data, which, in turn, will be disseminated and exploited for the benefit of human scientific knowledge. Space-Data Routers form an overlay suitable for exploiting space data efficiently, which is, by definition, a major objective of all space missions and probably the most significant failure today.


Title: Extending Internet into Space

Acronym: EIS

Starting Date: 01 June 2008

Duration: 48 months

Total Budget: 780K Euro

ESA Contribution: 780K Euro

Funded by the European Space Agency (ESA) in three phases. Coordinated by Prof. Vassilis Tsaoussidis, DUTH

This project elaborates on four major activities:

  • Evaluation of CFDP Service versus DTN service, full CFDP over full DTN and CFDP as file service over full DTN service. A roadmap from CFDP to DTN service will be discussed and evaluated based on scheduled activities for deployment in Space in 2023 and beyond.
  • Enhancements of the DTN Testbed in the context of Space Internetworking. This activity is associated with the design and deployment of a lightweight version of DTN for Space, in which some unnecessary functions of the bundle may be removed while others such as priorities and naming may be added.
  • Experiments with the Testbed, in three phases. These experiments will evaluate the functionality of DTN, the efficiency of DTN and the potential of DTN to provide reliable communication service through alternative channels.
  • Enhancement of the Testbed with Security mechanisms, which will be studied in depth.

The ultimate objectives of the project are highlighted below:

  • To integrate ESA policies and procedures into administrative protocol instructions.
  • To integrate realistic scenarios and applications into Testbed.
  • To allow for policy-based routing along with static and flexible dynamic routing.
  • To unify space and earth communications through layered architecture and convergence layers.
  • To evaluate all aspects of the new architecture adequately, emphasizing on security.
  • To determine - through experiments - the roadmap from CFDP to DTN


Other recent projects include:

  • DISCOS, 2010-11, funded by ESA (ongoing)
  • ICT ACTION IC0906: Wireless Networking for Moving Objects (WiNeMO) (FP7-COST, ongoing)
  • National Network of Excellence in High-Performance Computing (HellasHPC)(GSRT, ongoing)
  • COST 290: Wi-QoST - Traffic and QoS Management in Wireless Multimedia Networks(FP7-COST, completed in 2008)
  • PENED 2003: Transport Protocols for Heterogeneous Internets (GSRT, 142K, completed in 2010)