| Packet forwarding is a mission in wireless mesh networks. All nodes forward packets for each other such that they can communicate with distant nodes.;However, packet forwarding is a bandwidth- and energy-consuming activity. Therefore, it is unsurprised to find selfish nodes (selfish users) dropping the legitimate packets of their neighbours as to save their resources from depletion. The deviation is commonly known as packet drop attack and it causes serious disruption in network service.;Many detection protocols have been proposed to discourage the selfish behaviour in the network. However, most of them consider only dumb selfish nodes (DSNs) that drop packet in a regular manner. Accordingly, they fail to scrutinise a new type of smart selfish nodes (SSNs) that are intelligent and aggressive in maximising their benefits in the network. These SSNs work in two ways - they drop packets strategically (selectively and probabilistically) as to avoid detection; and/or they manipulate the detection protocol in order to defame the innocent nodes as packet droppers. Consequently, the SSNs can drop packets "legally" without being accused.;This thesis presents a robust packet drop attack detection protocol (named as Separation of Detection Authorities or SDA) that is aware of both DSNs and SSNs in the network. SDA uses a power-decentralised architecture; that is, the authorities are separated to a few entities such that no single entity is able to make adjudication unilaterally. The idea is commonly known as Separation of Powers as well.;Applying this principle, SDA distributes the detection, accusation and adjudication responsibilities to different entities. i.e. reporters, agents, and central authority. Reporters bring accusation against the misbehaved nodes; whereas the agents, as the third party, verify the accusation; and lastly the central authority concludes on the final judgement. In other words, no node can tamper the system all by itself (except the central authority).;Through analytical and simulation evaluation, the power-decentralisation of SDA is found to be able to provide promising detection results against both DSNs and SSNs. |
