An observer-based distributed scheme for selfish-node detection in a post-disaster communication environment using delay tolerant network

Aftermath of disaster causes severe destruction/damage to physical infrastructures. As a result, communication infrastructure gets disrupted for weeks. In such situations, smart-phone based adhoc opportunistic networks may be set up with the smart-phones carried by the relief workers (also referred as nodes) to communicate the situational information from different affected corners to some remote monitoring station. In such scenario, some malicious nodes may try to intercept and manipulate the sensitive situational data with the intention of corruption and fraud. One way of preventing such corruption is to devise an automated mechanism to detect and avoid the malicious nodes during data communication process. Reputation of nodes may be used as a measure to detect malicious nodes where reputation is estimated based on their degree of cooperation with other nodes in the network during data communication. In this paper, we propose an observer based dynamic reputation estimation technique for detection of selfish nodes where a group of independent roving observer nodes were introduced in the network to monitor the behavior of volunteer nodes as forwarder and receiver and to identify whether a node has any group-bias. Observers estimate the reputation of nodes based on their interaction patterns and group-biasness and periodically publishes global node reputation matrix based on which volunteer nodes may select an unselfish forwarder node during their data communication. The performance of the proposed scheme was evaluated on ONE simulator [19].