Department of Computer Science and Information Systems

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Subject: search.filters.subject.Delay Tolerant Networks

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    A message acknowledgment based congestion control (MACC) for delay tolerant networks
    (IEEE, 2016) Shekhawat, Virendra Singh
    Delay Tolerant Networks (DTNs) are vulnerable to intermittent connectivity due to opportunistic contacts between mobile nodes. Therefore, routing protocols designed for these networks rely on spreading multiple copies of data packets or messages in the network to achieve a better delivery ratio. Although, multiple copies of messages enhance the message delivery probability, but simultaneously these extra copies of messages occupy finite buffer space and scarce wireless bandwidth. Eventually, it results in message drops, delay in delivery and poor delivery ratio. This condition in DTNs is termed as network congestion. Further, this congestion is aggravated by the buffering of the delivered messages. Since destination based explicit acknowledgment packet generation is not feasible for such networks, therefore nodes have to buffer the delivered messages until their lifetime expires. Such messages significantly contribute in the congestion. To address the congestion occurred due to the buffering of delivered messages, we propose a node contact based message acknowledgment algorithm. In this algorithm, whenever nodes come into the contact with each other they exchange information about the delivered messages and update their relative message buffers. The proposed mechanism is routing protocol independent as well as it can be easily integrated with other congestion control mechanisms. Extensive simulations, with different mobility models, routing protocols and congestion control schemes, signify the improvement in message delivery ratio for the proposed mechanism.
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    De-COP: A Decentralized Community Convergence Approach for Message Forwarding in Pocket Switched Networks
    (IEEE, 2022) Shekhawat, Virendra Singh; Gautam, Avinash
    Pocket Switched Networks (PSNs) are an evolution of mobile ad-hoc and Delay Tolerant Networks in which there is no assumption made about the existence of a complete path between two nodes wishing to communicate, thus making routing even more challenging. Various routing algorithms have been proposed over the years like Epidemic, Spray and Wait, ProPHET, etc. There is a separate class of routing algorithms that exploit social structuralism to selectively forward messages to the best candidates. One such algorithm is BUBBLE Rap, which takes into account the notion of popularity and communities to make forwarding decisions. However, popularity as a sole deal-breaker is a rigid policy. We propose a decentralized community convergence-based message forwarding approach viz., De-COP that makes use of the familiarity metric which is dictated by the characteristic of a community to make message forwarding decisions. When familiarity is used for forwarding messages in converged communities, the messages are delivered with low latency and high probability. A community is defined as converged when the change in its membership is gradual. The forwarding node also takes into account the butter availability at the target node to reduce delay and message loss probability. The results were obtained using ONE simulator on two popular datasets, i.e., Infocomm06 and Cambridge to demonstrate the efficacy of the proposed De-COP approach in terms of improved delivery probability and message overhead ratio compared to ProPHET and BUBBLE Rap.