Trust Based Routing to Improve Network Lifetime of Mobile Ad Hoc Networks

Mobile Ad hoc Network is an impromptu wireless network consisting of mobile, self governing independent nodes. Routing in Mobile Ad hoc Networks has been a major concern due to its dynamic topology, lossy and unreliable links. In traditional routing, a single specific node is selected in prior as the potential next-hop forwarder for a packet. Unlike traditional routing, a category of routing technique termed Opportunistic Routing exploits the broadcast nature of wireless medium to compensate the unreliability of the packet transmissions in the channel. In Opportunistic Routing, one among the set of candidate nodes is selected as the potential next-hop forwarder using metrics like number of transmissions in a link, link error probability, cost, etc., for packet transmission. For selection and prioritization of candidates that ensures minimum number of transmissions from source to destination node, whilst improving the lifetime of the network on determining the residual battery energy, a new metric is proposed. This metric helps in improving the network lifetime considering the transmission powers in terms of the fraction of residual battery powers. Further, as nodes in mobile ad hoc networks are susceptible to attacks, a trust model based on direct, as well as indirect trust degrees from similar trusted neighbours is integrated in order to overcome the vulnerability due to attacks by malicious/selfish nodes and to provide reliable packet transmissions. Fading of trust is incorporated with a perspective to ensure the uncertainty of trust with time until it is updated

Defense and traceback mechanisms in opportunistic wireless networks

 In this thesis, we have identified a novel attack in OppNets, a special type of packet dropping attack where the malicious node(s) drops one or more packets (not all the packets) and then injects new fake packets instead. We name this novel attack as the Catabolism attack and propose a novel attack detection and traceback approach against this attack referred to as the Anabolism defence. As part of the Anabolism defence approach we have proposed three techniques: time-based, Merkle tree based and Hash chain based techniques for attack detection and malicious node(s) traceback. We provide mathematical models that show our novel detection and traceback mechanisms to be very effective and detailed simulation results show our defence mechanisms to achieve a very high accuracy and detection rate