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Routing in disruption tolerant networks
Saab Security and Defence Solutions division Communications develops communication equipment for tactical networks. These networks are characterized by heterogeneity in transmission technologies, link capacities as well as a high degree of mobility in the network. The difficulties are further compounded by intermittent connectivity. Single nodes or sometimes parts of the network occasionally loose connectivity with the rest of the network to later merge seamlessly with the same or another network. These networks are often referred to as Mobile Ad-hoc (MANET)  or Disruption/Delay Tolerant Networks (DTN) . New challenges to the design and management of tactical networks are imposed by the characteristics of MANETs and DTN. In particular, routing is more complicated in DTN than in ad-hoc networks since routing protocols in ad-hoc networks assume there is a path between source and destination. This, however, does not hold for delay tolerant networks. Instead, routing in delay tolerant networks need to rely on other mechanisms to forward traffic between source and destination.
This project aims to evaluate different well known DTN routing protocols. The evaluation should reflect the specific conditions delay tolerant networks face in a military setting, such as, security, mobility, jamming of radio signals and loss of nodes. The most well known routing protocols for DTN are Epidemic routing where all messages are forwarded on each available connection . This will ensure that the best possible route will be found since every possible path is used but it is also resource consuming in terms of communication bandwidth and memory consumption. A more sparse approach in terms of resource consumption is Spray and Wait  where the message is sent to a fixed number of neighbours. The message will be delivered when one of the nodes storing the message meet the destination node. This approach consumes a limited amount of memory and bandwidth but might in some situations take a long time until the message is delivered to the destination. An intermediate approach is to base forwarding decisions on historic data of encounters with other nodes. In the PrOPHET routing protocol  nodes exchange data on previous encounters in order to enhance the forwarding of messages in a DTN.
The project includes a requirement specification of DTN routing in a military setting. This specification is used to select a number of suitable routing protocols for the study. Furthermore, simulation will be used to evaluate the selected routing protocols. For this the routing protocols need to be implemented in a modern network simulator such as NS3  or omnet . The selection of simulation tool is based on the requirements of the evaluation. Although Jain et al.  focus their evaluation on DTN whith a high degree of scheduled connectivity different from DTNs in a military setting the paper can serve as a guide for the evaluation. The expected results of the project is an analysis of DTN routing in a military environment, implementation of a number of different DTN routing protocols in a modern network simulator as well as a written report of the evaluation.
This project is suitable for master’s students in computer science, electrical engineering, engineering physics or other relevant education. Excellent skills in C++ as well as analytical abilities are required. Furthermore, the student should be structured and be able to work independently. The project will be conducted at Saab SDS in Järfälla, Stockholm.
The application should include a short personal letter, CV and a transcript of grades from relevant university studies. Furthermore, a written report in English from a university course should also be enclosed with the application to evaluate the student’s ability to express him/her self in written English. Upon request the student should also be prepared to provide samples of programming code.
Send your application by email to [email protected]
Contact: Anders Gunnar +46 8 580 853 40
 Mobile Ad hoc Networking (MANET): Routing Protocol Performance Issues and Evaluation Considerations, RFC 2501.
 K. Fall,A Delay-Tolerant Network Architecture for Challenged Internets, SIGCOMM, August 2003.
 NS-3 Network simulator, http://www.nsnam.org
 Omnet++, http://www.omnetpp.org/
 A. Vahdat and D. Becker, Epidemic routing for partially connected ad hoc networks, Technical report CS-200006, Duke University, 2000.
 T. Spyropoulos, K. Psounis and C. Raghavendra, Spray and wait: An efficient routing scheme for intermittently connected mobile networks, In Proc. Of WDTN 2005.
 A. Lindgren, A. Doria, and O. Schelen, Probabilistic routing in intermittently connected networks. SIGMOBILE Mob. Comput. Commun. Rev., 7(3):19–20, 2003.
 S. Jain, K. Fall and R. Patra, Routing in a delay tolerant network, in Proc. SIGCOMM 2004, Portland, Oregon, USA, August 2004.
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