Abstract
Modern communication infrastructures that usually keep people always on-line and inform “on-the-go” have repeatedly proved to be unreliable and unavailable during and after major disasters. In those situations the prime need is to quickly re-establish minimal communication infrastructures to start rescue operations. DTN is described by a special kind of mobile ad-hoc network where sparseness, large communication delay and lack of end to end path from source to destination exist. It is evident from this fact that data forwarding is dependent on the cooperation of multiple hops in “store-carry-forward” manner. However, nodes involved in communication may sometimes behave maliciously and may non-cooperate. So, the objective in this perspective is to develop a reliable data forwarding scheme by detecting malicious activities and encourage nodes to participate in Post Disaster Communication environment. Analysis of the proposed system, its protocols and performance studies are implemented and tested using Opportunistic Network Environment (ONE) simulator.
TopIntroduction
Now-a-days Delay/Disruption Tolerant Network (DTN) is used in post-disaster situation to assist rescue operation. As it is a special type of wireless network with sporadic connectivity, lacks of infrastructure, very long delays due to network partitioning, are the universal aspects.
In DTN, messages, also called bundles, are propagated using hop by hop fashion and buffered at the next hop until the next hop appears. This propagation process is named as store-carry-forward method where the users are opportunistic in nature. As in DTN end to end communication is no longer possible, data are forwarded in hop by hop approach via intermediate nodes (Chakrabarti, & Roy, 2015; Chakrabarti et al., 2014). As a result, the architecture of DTN relies on the cooperation among nodes participating in data communication (Chakrabarti, Banerjee, & Chakrabarti, 2014). However, the intermediate nodes may sometimes become selfish (Chakrabarti, & Roy, 2015; Chakrabarti et al. 2014; Chakrabarti, Banerjee, Chakrabarti, Chakraborty, 2014a; Banerjee et al, 2014; Chakrabarti, Banerjee, Chakrabarti, Chakraborty, 2014b; Banerjee, Chakrabarti, Chakraborty, Chakrabarti, 2014; Chakrabarti, 2014). Nodes may be selfish due to deficiency of its energy (battery power) or due to some malicious intention (Chakrabarti, Chakrabarti, Banejee, 2015). Therefore, how to efficiently and effectively resolve the selfishness problem has become the most challenging issue to achieve better packet delivery performance of DTNs. The most popular way is to detect and avoid those selfish nodes during data communication.
A node’s selfishness may be typified as non-cooperation or dropping of messages (Chakrabarti et al., 2014; Chakrabarti, Banerjee, Chakrabarti, Chakraborty, 2014a; Chakrabarti, Banerjee, Chakrabarti, Chakraborty, 2014b). Miao et al. (2012) classify selfish behavior into two categories: individual selfishness and social selfishness.
Individual selfishness is defined as the reluctance of a single node to relay others’ messages, may be due to protect its limited resources or due to some malicious intention.
On the contrary, if a node belongs to a certain community, it is always willing to relay messages for the nodes within the same community/group but renounces to relay messages for the nodes outside its community/group (Wei et al., 2011). This is termed as social selfishness.
Key Terms in this Chapter
Non-Cooperative Node: A node, which is unwilling to forward or receive other node’s messages.
Cooperation Pattern: The communication characteristics of nodes are known as cooperation pattern. In Delay Tolerant Network, due to resource limitation, all the nodes may not be cooperative. So, cooperation pattern is one of the most important parameter to judge any node’s behavior.
Reputation: Reputation implies the social tie-up pattern of a person in his associated environment. In a wireless network, when two nodes encounter each other, they can develop a perception about each other by checking their reputation values.
Intermittent Connectivity: In Delay Tolerant Network, due to nodes’ movement, connectivity is not fixed always. Such inconsistent connectivity is called intermittent connectivity.
Trusted Authority: The authorized node, which is responsible to monitor other nodes’ behavior or cooperation pattern, is termed as Trusted Authority node.
Incentive: Incentive is a kind of stimulation given to the nodes in order to increase their cooperation in a resource-constrained environment like Delay Tolerant Network.
Selfish Node: A node, which drops other node’s messages after receiving.
Malicious Node: The node which modifies data before, during or after transmission is known as malicious node.