ANALYSIS AND MITIGATION OF SELFISHNESS IN DELAY TOLERANT NETWORKS (DTN)

Abstract

N Delay Tolerant Networks, routing and data dissemination is performed in highly challenging wireless environment. No end-to-end connection exists in DTN due to ..I. frequent node mobility. Routing is challenging in these types of networks because of the dynamic routing tables, which is the result of frequently changing network topology. DTN works in a store-carry-forward fashion. DI'N Routing can be divided into opportunist routing, social based routing and incentive based routing. In opportuntic routing, the relay node is selected based on its opportunity of meeting the destination node. In social based routing the relay is selected in such a way that it has social ties with the destination node. In incentive based routing, credits are given to the relay node for forwarding the message. For the routing algorithm to work properly in this type of network, it is required for the relay node to act selflessly, which is not the case in the real world. A node in a Delay Tolerant Network is considered as selfish when that node is not willing to forward the packet further in the network. There can be various scenarios present in which few nodes in a network can act selfishly. We have discussed two types of selfishness. individual and social, that can be present in the network. Individual selfishness is when selfish nodes do not want to store messages of other nodes because of their limited buffer space. Social selfishness is when a node acts selfishly towards another node only if the latter is not a friend of the former. We then analyze the effects of these two types of selfishness on opportunistic DTN routing algorithms, and propose a technique to impro'e the packet delivery ratio of the existing algorithms by mitigating the selfishness involved. We have done the empirical and real test bed analysis of the algorithms. For the empirical analysis we have used three different mobility models and analyzed the effect of different type of selfish behavior on the delivery ratio of the algorithms. For the analysis with real-test bed, we have implemented the algorithms on Freeduino board. The Freeduino board is then mounted on TRK-MPC5604B Motor Car. A set of cars, then communicates with each other with the help of XBee Module-ZB Series 2 depending on the underlying protocol.