The increasing pervasiveness of mobile devices with networking capabilities has led to the emergence of Mobile Delay Tolerant Networks (MDTNs). The characteristics of MDTNs, which include frequent and long-term partitions, make message routing a major challenge in these networks. Most of the existing routing protocols either allocate an unlimited number of message copies or use a fixed number of message copies to route a message towards its destination. While the first approach unnecessarily floods the network, the rigidity of the second approach makes it inefficient from the viewpoint of message replication. Hence, the question that we address in this paper is: "how to dynamically allocate message copies in order to strike a balance between the delay and cost of message delivery?". We present a novel adaptive multi-step routing protocol for MDTNs. In each routing step, our protocol reasons on the remaining time-to-live of the message in order to allocate the minimum number of copies necessary to achieve a given delivery probability. Experiment results demonstrate that our protocol has a higher delivery ratio and a lower delivery cost compared to the state-of-the-art Spray-and-Wait and Bubble protocols.

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A delay and cost balancing protocol for message routing in mobile delay tolerant networks

In mobile Delay Tolerant Networks (DTNs), messages are routed in a mobility-assisted manner. Therefore, the willingness of nodes to relay messages for other nodes plays a significant role in the routing process. Moreover, since the resources in mobile devices are generally limited, carriers of mobile devices may be unwilling to relay messages for other nodes in order to conserve their scarce resources. Furthermore, recent studies on the impact of selfish behavior in DTNs show that the performance metrics (i.e., delivery ratio, delivery overhead, and delivery latency) are severely influenced if a major portion of the nodes is selfish. A number of strategies have been proposed to prevent the impact of selfish behavior. It is therefore necessary to give an overview of the representative strategies. In this paper, we first classify the different types of selfish behavior. The existing strategies for preventing selfish behavior are traditionally classified into three categories: barter-based, credit-based and reputation-based. We then survey some representative strategies in the literature belonging to each category. Finally, we conduct experiments to compare the performance of these strategies for preventing different types of selfish behavior.

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An Analysis of Strategies for Preventing Selfish Behavior in Mobile Delay Tolerant Networks

The routing efficiency in delay tolerant networks is degraded due to intermittent connection and high latency Additionally, socially selfish nodes in social networks refuse to provide message forwarding service since there are limited resources To solve these problems, an improved routing algorithm based on the social link awareness is proposed In this algorithm, multiple social features of the nodes' behaviors are utilized to quantify the nodes pairs' social links The social links of the nodes pairs are computed based on their encounter history These social links can be used to construct the friendship communities of the nodes The intra-community and inter-community forwarding mechanisms are implemented to raise the successful delivery ratio with low overhead and decrease the transmission delay Simulation results show that the proposed algorithm shortens the routing delay and increases the successful delivery ratio, thereby improving the routing efficiency

An Improved Routing Algorithm Based on Social Link Awareness in Delay Tolerant Networks

To what extend a wireless communication gadget can chip away at a single charge of a rechargeable battery obtains the importance. Capacity-wise, disposable batteries are superior to the rechargeable batteries. There are numerous ways utilized with which the battery life can be augmented. At the same time, identifying the cause of battery energy utilization boosts the researchers to design and develop protocols, methods and techniques to minimize the consumption of energy by which lifetime of the network could be extended. This paper investigates the sources and factors that lessen the network lifetime. The scope of this paper has been narrowed down to Delay Tolerant Network since this field of research has attracted a great deal of attention by the researchers mostly due to its challenging characteristic qualities. No promising connectivity, high mobility, indefinite node mobility patterns, energy and storage exhaustion comprise a few of the potential issues that one may confront in a DTN environment which in turn eat-off bandwidth and energy for the data delivery from the Source to the Destination.

A Survey of Factors Influencing Network Lifetime in Delay Tolerant Network

Routing protocol based on social characteristics for opportunistic networks

Due to the lack of end-to-end paths between the communication sources and destinations, the routing of Delay Tolerant Networks (DTN) exploits the store-carry-and-forward mechanism. In this new routing mechanism, how to efficiently integrate forwarding and replication mechanisms is significant for achieving high message delivery ratio while requiring low delivery cost. In this paper, by using famous social properties such as communities and centrality, we design a routing scheme efficiently Integrating Forwarding and Replication (IFR), which allow node to replicate messages in the same community and to forward messages outside the community according to delivery weight obtained from node centrality. Realistic traces based simulations show that our scheme IFR is efficient in improving the message delivery performance on the tradeoff between the delivery success ratio and total delivery cost.

Su Li

Papers

Integrating Forwarding and Replication in DTN Routing: A Social Network Perspective