Important Events

User login


Syndicate content

Contact details

Contact WCL

Tel: +30 2610 996496
+30 2610 996480
Fax: +30 2610 997336
+30 2610 991855
Email: raniadou [AT]
Electrical and Computer Enginnering Department
University of Patras


OPNET Technologies
7255 Woodmont Avenue
Bethesda, MD 20814
Tel: 240-497-3000
Fax: 240-497-3001

© 2008 OPNET Technologies, Inc.
OPNET and OPNET Technologies Inc.
are registered trademarks of OPNET.
All trademarks are the property of their respective owners and are used herein for identification purposes only.

University: University of Patras
Name of sponsoring Professor: Assistant Professor Spyros Denazis
Department: Department of Electrical & Computer Engineering
Laboratory: Wire Communications Laboratory

P2P Research Group

We focus in the creation of P2P network architectures and systems that
are scalable, stable, with high resource utilization and adaptable to
underlying network. Now we focus in the creation of a P2P content
distribution system. According to the aforementioned requirements our
major tasks are:

  • An overlay which is the graph for the interconnection of peers
  • A scheduler which runs in every peer and ensures the on time and reliable distribution of the content.
  • A scalable, dynamic and accurate bandwidth monitoring system that participating peers have.
  • A bandwidth control system that handles and the supply of extra bandwidth in cases when peers' aggregated resources are insufficient to sustain the streaming process
  • A peer-to-peer system that is responsible for the storage and query of objects available for streaming.


1. P2P live streaming

Peer-to-peer live streaming is a network application, where peers (users) contribute their upload bandwidth for the real time distribution of a video stream. The objective of this work is the optimization of this data diffusion with a distributed and self-organized architecture. Peers have heterogeneous and dynamic uploading bandwidth. This fact combined with the characteristics of the topology of the underlying network and the dynamic traffic conditions e.g. latency create a volatile and complex environment for P2P live streaming delivery, which strongly affect the success of a P2P system measured by a number of performance metrics.

Authored Papers:

  • Efthymiopoulos N, Christakidis A, Denazis S, Koufopavlou O.
    Liquidstream - network dependent dynamic P2P live streaming, Springer Peer-to-Peer Networking and Applications, March 2011, Vol. 4, No 1, pp. 50-62, DOI: 10.1007/s12083-010-0092-0 (link:
  • Nikolaos Efthymiopoulos; Spyridon L. Tompros, Athanasios
    Christakidis Konstantinos Koutsopoulos, Spyros Denazis, Enabling live video streaming services realization in telecommunication networks using P2P technology, Wiley International Journal of Communication Systems, March 2011, DOI:10.1002/dac.1250 (link:
  • Christakidis Athanasios, Efthymiopoulos Nikolaos, Denazis Spyros, Koufopavlou Odysseas. P2P-InfoReflect :Dynamic Locality-Aware and Multi-Balanced Overlay for Network Dependent Applications & Services The IEEE International Workshop On Peer-to-Peer Web Services, 25-27 Sept. 2008, pp. 929 - 934, DOI 10.1109/HPCC.2008.142 (link:
  • Efthymiopoulos Nikolaos, Christakidis Athanasios, Denazis Spyros, Koufopavlou Odysseas, Enabling locality in a balanced peer to peer overlay IEEE Globecom 2006 - in World Class Solutions - Networking the Globe Symposium, Nov. 2006, pp. 1-5, DOI 10.1109/GLOCOM.2006.244

2. Deploying and experimenting with new control architectures: The VITAL++ case

VITAL++ mainly aspires at defining and illustrating a new communication paradigm that will demonstrate how content-based applications and services, highly heterogeneous in terms of user functions and distributed in the network, can be enrolled in the frame designated by the operations of traditional telecommunication networks and thus be widely available to the users with proper QoS, security and adequate privacy.

Authored Papers:

  • Christakidis A, Efthymiopoulos N, Fiedler J, Dempsey S, Koutsopoulos K, Denazis S, Tombros S, Garvey S,Koufopavlou O. VITAL++ a new communication paradigm: embedding P2P technology in next generation networks, IEEE Communications Magazine, January 2011, Vol. 49, No 1, pp. 84-91, DOI 10.1109/MCOM.2011.5681020  (link:
  • Athanasios Christakidis, Jens Fiedler, Nikolaos Efthymiopoulos, Konstantinos Koutsopoulos, Spyros Denazis, Spyridwn Tombros, Shane Dempsey, Odysseas Koufopavlou, Integrating P2P with Next Generation Networks River Publishers Series in Communications, Advances in Next Generation Services and Service Architectures. ISBN: 978-87-92329-55-4.


University: University of Patras
Name of sponsoring Professor: Associate Professor Michael Logothetis
Department: Department of Electrical & Computer Engineering
Laboratory: Wire Communications Laboratory


Wireless LAN Simulation

Using Opnet modeler, we have made simulations of scenarios employing wireless LANs (WLANs) under the 802.11 – 802.11e protocols, studying the performance of the WLAN.

Authored Papers:

  • I. Papapanagiotou, J. S. Vardakas, M.D. Logothetis and S.A. Kotsopoulos, “Performance Evaluation of IEEE 802.11e based on ON-OFF Traffic Model”, in Proc. of the 3rd International Mobile, Multimedia Communications Conference, Mobimedia 2007, Nafpaktos, Greece, 27-29 August 2007.
  • J. S. Vardakas, M. K. Sidiropoulos and M. D. Logothetis, "Performance Behavior of IEEE 802.11 Distributed Coordination Function", IET Circuits, Devices & Systems, Vol. 2, No. 1, pp. 50-59, February 2008.


Lab exercises for the course Computer Communication Networks:

  1. Simulation of waiting systems
  • Introduction to OPNET modeler
  • Simulation of the M/M/1/? waiting system
  • Simulation of the M/M/1/m waiting system
  1. Simulation of the Ethernet protocol
  • Description of the Ethernet protocol
  • Simulation of an Ethernet network
  1. Simulation of multiple access protocols
  • Simulation of the Aloha protocol
  • Simulation of the CSMA protocol
  • Simulation of the CSMA/CD protocol
  1. Simulation of the IEEE 802.11 protocol:
  • Description of the IEEE 802.11 protocol
  • Analytical model for the calculation of the saturated throughput of the wireless LAN, using a programming language
  • Simulation of the IEEE 802.11 protocol
  • Evaluation of the presented analytical model through the comparison of analytical and simulation results
  1. Simulation of packet-switched networks
  • Simulation of a packet-switched network, in order to find the end-to-end delay of a packet


University: University of Patras
Name of sponsoring Professor: Associate Professor Dimitris Lymberopoulos
Department: Department of Electrical & Computer Engineering
Laboratory: Wire Communications Laboratory


1. IP Multimedia Subsystem (IMS) architecture simulation and implementation of Multimedia Services.

2. Quality of Services (QoS) and applications on Next Generation Networks.

This simulator will be used for the diploma theses of the 5th-year under-graduate students and for further investigation regarding NGN networks.


University: University of Patras
Name of sponsoring Professor:
Stavros A. Kotsopoulos
Department:Department of Electrical & Computer Engineering

Laboratory: Wireless Telecommunication Laboratory


1. Wireless LAN Simulation:

IP Telephony is a driving force for research and investments in the Internet and Network applications. With the advent of WMAN 802.16, the wireless VoIP is expected to be the hot application embedded in every wireless handheld. Along with the Broadband Access, local access is expected to play an important role. Using OPNET Modeler, we are currently making simulation of scenarios employing WLANs, WMANs and VoIP calls, studying the behaviour and the weaknesses of the system.

Authored papers :

  • A Heuristic strategy for IEEE 802.16 WiMAX scheduler for Quality of Service, G. S. Paschos, I. Papapanagiotou, C.G. Argyropoulos, S.A. Kotsopoulos, 45th Congress FITCE 2006, 30 August - 2 September 2006, Athens, Greece.

2. Ad Hoc Networking Simulation:

Ad Hoc Networking is a key topic for Wireless Communications. The wireless computers are able to communicate without the need of any infrastructure at all. We use OPNET Modeler to simulate Ad hoc Routing Protocols, MAC Layer Enhancements and Quality of Service behaviour.

Authored papers:

  • Performance analysis of a new Admission Control for 802.11 WLAN Networks in ad hoc mode, G. S. Paschos, I. Papapanagiotou, E.D. Vagenas, S.A. Kotsopoulos, CSNDSP 2006, 19-21 July, Patras.

3. Wireless Sensor Networks:

Sensor Networks is an amazing application of wireless Networks. Small, low-cost and easy to build nodes are deployed in an area able to sense activities and report through ad hoc communications. Using OPNET Modeler, we simulate Sensor Localization and Power Management.


University: University of Patras, Greece
Name of sponsoring Professor:
Prof. Dr. Stavros Koubias (
Department: Department of Electrical & Computer Engineering (

Research Group: Applied Electronics Laboratory (APEL) (


Routing and MAC layer in Wired and Wireless Networks

The OPNET simulator is be used for research purposes in the Applied Electronics Laboratory, Dept. of Electrical & Computer Engineering, University of Patras. More specifically, this simulator is be used mainly by post-graduate students working on their PhD theses. The main fields of this research work belong in the following categories:

  • Distributed Real-Time Networking Systems

  • Industrial Fieldbuses

  • Wireless High-Performance Real-Time Networks

  • Sensor Networks

  • Hybrid (Wired/Wireless) Networking Structures

  • Interworking Structures for High-Speed Networks

In addition this simulator will be used for the diploma theses of the 5th-year under-graduate students for the course of "Distributed Embedded Real-Time Systems", which is equivalent of a Master thesis. Until know the following diploma thesis have been completed:

  • Study and development of self-organized wireless sensor networks.

Authored Papers:

22/9/2004 - WFCS 2004 : A Hybrid Adaptive Routing Protocol for Ad Hoc Wireless Networks (pdf)

19/9/2005 - ETFA 2005 : ZRP versus DSR and TORA-A comprehensive survey on ZRP performance(pdf)

OPNET Technologies, Inc. is a leading provider of solutions for managing networks and applications. OPNET's best-in-class solutions address application troubleshooting, application monitoring, network monitoring, network configuration management, capacity management, and network simulation. OPNET’s solutions have been operationally proven in thousands of customer environments worldwide, including corporate and government enterprises, government and defense agencies, network service providers, and network equipment manufacturers. For more information about OPNET and its products, visit