A mobile code bundle extension for application-defined routing in delay and disruption tolerant networking

Grup de recerca SENDA (Security of Network and Distributed Applications)In this paper, we introduce software code to improve Delay and Disruption Tolerant Networking (DTN) performance. DTN is extremely useful when source and destination nodes are intermittently connected. DTN implementations use application-specific routing algorithms to overcome those limitations. However, current implementations do not support the concurrent execution of several routing algorithms. In this paper, we contribute to this issue providing a solution that consists on extending the messages being communicated by incorporating software code for forwarding, lifetime control and prioritisation purposes. Our proposal stems from the idea of moving the routing algorithms from the host to the message. This solution is compatible with Bundle Protocol (BP) and facilitates the deployment of applications with new routing needs. A real case study based on an emergency scenario is presented to provide details of a real implementation. Several simulations are presented to prove the feasibility and usability of the system and to analyse its performance in comparison to state-of-the-art approaches

An Analytical Incorporation of Power Priority Model with Replication and Expedition based Routing Protocol

Delay tolerant network (DTN) is a class of wireless ad-hoc network. It works when end to end direct path does not exist between source and destination by using the Store and Forwarding routing mechanism. DTN has several features such as long delay, limited resources, high error rate, reliable transmission etc. Its application fields are in wildlife behavior monitoring, military battle field, post disaster communication, under water communication and many more. The purpose of this paper is to compare between two different strategic (Replication and Expedition based) routing protocols with the Power Priority Model, which is proposed in recently. The evaluated result of this performance analysis was obtained from Opportunistic Network Environment (ONE) simulator on various performance metrics such as, Delivery Probability, Overhead ratio, Average latency and Hop count

Performance Assessment of Aggregation and Deaggregation Algorithms in Vehicular Delay-Tolerant Networks

Vehicular Delay-Tolerant Networks (VDTNs) are a new approach for vehicular communications where vehicles cooperate with each other, acting as the communication infrastructure, to provide low-cost asynchronous opportunistic communications. These communication technologies assume variable delays and bandwidth constraints characterized by a non-transmission control protocol/ internet protocol architecture but interacting with it at the edge of the network. VDTNs are based on the principle of asynchronous communications, bundleoriented communication from the DTN architecture, employing a store-carryand- forward routing paradigm. In this sense, VDTNs should use the tight network resources optimizing each opportunistic contact among nodes. At the ingress edge nodes, incoming IP Packets (datagrams) are assembled into large data packets, called bundles. The bundle aggregation process plays an important role on the performance of VDTN applications. Then, this paper presents three aggregation algorithms based on time, bundle size, and a hybrid solution with combination of both. Furthermore, the following four aggregation schemes with quality of service (QoS) support are proposed: 1) single-class bundle with N = M, 2) composite-class bundle with N = M, 3) single-class bundle with N > M, and 4) composite-class bundle with N > M, where N is the number of classes of incoming packets and M is the number of priorities supported by the VDTN core network. The proposed mechanisms were evaluated through a laboratory testbed, called VDTN@Lab. The adaptive hybrid approach and the composite-class schemes present the best performance for different types of traffic load and best priorities distribution, respectively

Reputation and credit based incentive mechanism for data-centric message delivery in delay tolerant networks

In a Data-centric Delay Tolerant Networks (DTNs), it is essential for nodes to cooperate in message forwarding in order to enable successful delivery of a message in an opportunistic fashion with nodes having their social interests defined. In the data-centric dissemination protocol proposed here, a source annotates messages (images) with keywords, and then intermediate nodes are presented with an option of adding keyword-based annotations in order to create higher content strength messages on path toward the destination. Hence, contents like images get enriched as there is situation evolution or learned by these intermediate nodes, such as in a battlefield, or in a disaster situation. Nodes might turn selfish and not participate in relaying messages due to relative scarcity of battery and storage capacity in mobile devices. Therefore, in addition to content enrichment, an incentive mechanism is proposed in this thesis which considers factors like message quality, battery usage, level of interests, etc. for the calculation of incentives. Moreover, with the goal of preventing the nodes from turning malicious by adding inappropriate message tags in the quest of acquiring more incentive, a distributed reputation model (DRM) is developed and consolidated with the proposed incentive scheme. DRM takes into account inputs from multiple users like ratings for the relevance of annotations in the message, message quality, etc. The proposed scheme safeguards the network from congestion due to uncooperative or selfish nodes in the system. The performance evaluation shows that our approach delivers more high priority and high quality messages while reducing traffic at a slightly lower message delivery ratio compared to ChitChat --Abstract, page iv

Delay Tolerant Networking over the Metropolitan Public Transportation

We discuss MDTN: a delay tolerant application platform built on top of the Public Transportation System (PTS) and able to provide service access while exploiting opportunistic connectivity. Our solution adopts a carrier-based approach where buses act as data collectors for user requests requiring Internet access. Simulations based on real maps and PTS routes with state-of-the-art routing protocols demonstrate that MDTN represents a viable solution for elastic nonreal-time service delivery. Nevertheless, performance indexes of the considered routing policies show that there is no golden rule for optimal performance and a tailored routing strategy is required for each specific case