Bundles fragmentation in Vehicular Delay-Tolerant Networks

Abstract

Vehicular Delay-Tolerant Networks use the delaytolerant architecture and protocols to overcome the disruptions in network connectivity. These concepts help in cases where the network is sparse or with large variations in density or there is no end-to-end connectivity, by providing a communications solution for non real-time applications. This paper presents data fragmentation techniques to optimize the efficiency of data delivery for the case of the short node contacts that characterize vehicle networks. The techniques were tested in a laboratory environment with portable digital assistants and Lego Mindstorm NXT robotic cars. If no fragmentation is used, only small messages are successfully transferred. Proactive fragmentation fragments messages to a predefined size in the source node. Reactive fragmentation adjusts the fragment sizes to the real duration of the contact when it is broken. Reactive fragmentation showed a good efficiency in adapting the fragmentation in real time to the contact duration. Proactive fragmentation can perform slightly better if the fragment sizes are carefully chosen as it requires less processing. As this choice is difficult, reactive fragmentation is more practical to use.

Performance assessment of fragmentation mechanisms for vehicular delay-tolerant networks

“…The study proposed in [24] confirms this statement. It presents several fragmentation techniques for VDTNs in order to optimize the efficiency of data delivery for the case of the short node contacts that characterize vehicle networks.…”

Markov decision‐based optimisation on bundle size for satellite disruption/delay‐tolerant network links

“…The authors in [17] analyse the effect of aggregation of data bundles in asymmetric space communication channel, and find the amounts of bundles which should be aggregated within a block over highly asymmetric channels. The work in [18] compares bundle fragmentation techniques with respect to average message delivery time in the vehicle network, based on a real test‐bed environment. In [19, 20], one realistic application in DTN scenario is proposed for a so‐called Ring Road network for the improvements of delivery time.…”

Connection Time Estimation between Nodes in VDTN

“…Delay tolerant networks (DTN) are the type of ad-hoc networks, where end to end connectivity does not exist. DTN has a message-oriented overlay layer called "Bundle Layer" employs a store, carry and forward message switching paradigm that moves messages from node to node, along with a path that eventually reaches the destination [2]. It works as follows that a source node creates messages which are called bundles and store that message in its internal storage until it meets with another node.…”

“…With TCP 4 out of 10 attempts was not useful because TCP is connection-oriented and take more time, however with UDP results were better. So, the authors of [2] give a solution of message fragmentation. This work suggests if "estimatedtime" is calculated correctly, fragmentation will not be www.ijacsa.thesai.org required any longer and still it will be possible to send data with a good success ratio.…”