Efficient Routing in Delay Tolerant Networks Analysis and Design

Today's wired and wireless networks have enabled interconnections among a wide range of computing devices including smart phones and tablets laptops. However traditional network techniques e.g. TCP IP fail to provide sufficient connectivity in environments with highly dynamic network topology and frequent network partition due to mobility. Delay Tolerant Networks DTNs have been introduced to fill in this gap. Unlike conventional networks such as the Internet DTNs suffer from a lack of end to end connections long communication delays and limited computing and storage resources. Consequently routing protocols designed for traditional networks are not suitable for DTNs. In addition the special characteristics of DTNs pose unique security challenges that need to be addressed in the design of routing protocols. This thesis investigates the issue of designing low overhead and secure protocols for packet forwarding in DTNs and presents two novel routing schemes: Trust based Spray and Wait TB SnW and Fine Grained PRoPHET FG PRoPHET . TB SnW extends the Spray and Wait routing protocol by exploiting a distributed trust management mechanism to mitigate blackhole attacks in DTNs. Each device maintains history records of successful message delivery and uses this information to detect and mitigate blackhole attackers. Simulation results show that TB SnW protocol achieves better robustness against blackhole attacks when compared with the Spray and Wait protocol. Fine Grained PRoPHET FG PRoPHET aims at enhancing the message delivery rate without overwhelming the network's scarce resources. Different from most existing routing schemes FG PRoPHET maintains fine grained history records on successful message delivery to make more accurate forwarding decisions to improve message delivery rate. Moreover FG PRoPHET integrates a greedy algorithm in an attempt to avoid overwhelming the network scarce resources. Simulation results show that FG PRoPHET considerably outperforms Epidemic and PRoPHET routing schemes by producing more accurate routing decisions resulting in significant increase of successful message delivery rate and better handling of the network buffer resources