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University: University of Bremen, Germany
Professor: Carmelita Görg
Department: Department of Communication Networks


Teaching courses 2009/2010

 

OPNET Simulation Environment has been used at the Department of Communication Networks (ComNets) of the University of Bremen, Germany, for following areas of research:

1) Modeling and Simulation of the Transport Network Layers of the UTRAN Access Network

UMTS networks allow the transmission of voice and data with appropriate quality of service (QoS). The Release 99 transport layer of the UMTS terrestrial radio access network (UTRAN) is based on ATM. Other IP-based solutions are foreseen for later releases.

This investigation at the University of Bremen is focused on the transport layer of the UTRAN, i.e. the Iub interface between the Radio Network Controller (RNC) and the Node B (base station with the antenna). It evaluates ATM and IP-based solutions to enable a comparison. This interface is one the most crucial ones. With the extension of the UTRAN to cover more and more suburban and rural areas, the bandwidth between RNC and a Node B becomes limited and expensive. Therefore, Node B and RNC must be enabled to use the limited transmission resources in the most efficient way.

In the first release of UMTS (Release 99), 3GPP has specified ATM (Asynchronous Transfer Mode) as the transport technology on the Iub interface. Above the ATM layer, AAL2 protocol is chosen for transporting the data user plain traffic over the Iub link, because the traffic on the Iub interface has to obey strict real-time requirements to achieve a synchronous behavior on the radio interface. The AAL2 protocol allows the efficient multiplexing of several data flows over a single ATM virtual channel and is dedicated for efficient transmission of low-bit-rate services with stringent requirements in terms of delay through an ATM network.


2) Modeling and Simulation of Mobile Ad hoc NETworks (MANET)

OPNET is used to evaluate MANET protocols through simulation modeling and also to add upcoming MANET protocols for further simulations. Following is the list of work that has been completed and planned.

  • Implementation of DYMO IETF Draft in OPNET 11.0. Source code is available at the contributed models ftp server of OPNET and here.

  • The DYMO protocol has been extended to find interference aware multi-path routing called Radio Disjoint Multi-path (RDM) routes. OPNET 11.0 has been modified to implement RDM routes and also to distribute packets of a single flow by replicating and splitting. The details of this implementation were presented in OPNETWork 2007 conference.

Above implementations were used for following MSc Master Theses and Mini-project work at ComNets, University of Bremen.

  • MSc Master Thesis: Modeling Radio Disjoint Multi-path Routing for Wireless Ad hoc Networks. In this work, RDM implementation of OPNET is used to take the simulation results to be compared with analytical results. Simulation results are taken in scenarios with different topologies.

  • MSc Master Thesis: Simulation and Analysis of Packet Replication over Multi-Path Routing in MANET. In this work, OPNET source code is modified to replicate packets over multiple RDM paths. Simulation results are used to analyze the behavior of replicating for both UDP and TCP based protocols in detail.

  • MSc. Mini-Project Thesis: Performance Comparison of AODV, DYMO and DSR with TCP and UDP Applications. In this work, the performance of above three protocols is compared in different networks of MANETs considering different mobility patterns.

  • MSc. Mini-Project Thesis: Performance Analysis of AODV using OPNET Simulator. This project was done on OPNET 10.5 modeler with the wireless module
Above implementations were used to take simulation results for following papers that are published by ComNets, University of Bremen.

Planned Work

  • Detailed performance analysis of RDM routes. This should consider the different network topologies used in real applications such as firefighting scenarios. These scenarios should use wireless module to enable different types of mobility patterns

  • Enhanced the simulation results used to compare the analytical results to measure the sustainable throughput for bi-directional UDP and TCP based applications

  • Implement multiple flow distribution to distribute individual flows among RDM paths

  • Release of the source code for RDM implementation


3) Modeling and Simulation of IEEE 802.15.4 based Wireless Sensor Networks

Wireless Sensor Networks (WSNs) are a research area of growing importance within the Wireless Networks research community. One of the major issues in this area is the search for efficient routing methods.
Extending the OPNET models from open-ZB, node models and simulation scenarios for WSNs are created. These models and scenarios are especially used for design and evaluation of routing concepts for WSNs.
The work described in this section was done on OPNET 11.5 with the wireless module.

  • Report OPNET Simulation of Firefighter Scenario: Simulation of a WSN as virtual lifeline for firefighters.

  • Master Thesis: Opportunistic Routing in Multi-Sink Mobile Ad-hoc Wireless Sensor Networks
    In this master thesis, an opportunistic routing protocol for intermittently connected Wireless Sensor Networks was designed. In this protocol, the sensor nodes decide which next hop to send the data to by evaluating the signal strength and the relative node movement. The protocol was simulated and evaluated in OPNET.
    Final presentation of the master thesis concept and results.

Future work
  • Design and evaluation of multi-criteria context-aware routing concepts for Wireless Sensor Networks

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