Research On Multicast Routing Technology In Delay Tolerant Network

With the emergence of a large number of short-range wireless communicationequipments, nowadays applications on delay tolerant networks (DTN) becomeresearching hotspot. DTN which relies on mobile device is self-organizing networkand its topology is changing with high-speed. This leads to instability of linksbetween nodes. Meanwhile, the Pub/Sub system becomes more and more popular forits asynchronous and multi-points communications. Achieve such Pub/Sub multicastrouting under DTN scenarios, the design of routing faces many challenges.In order to propose an effective Pub/Sub multicast routing for DTN, this paperproposes PSD (a Routing Protocol for Publish/Subscribe in DTN) multicast routingbased on previous algorithm. PSD is a limited message routing for DTN. PSD adjuststhe number of copies adaptively according to the contact of the nodes and the densityof subscribers in the whole network. In PSD, the Publisher receives the subscriptionrequest continuously, meanwhile the Publisher statistics the number of request onreal-time. Then it sends limited message to the subscribers. In addition, PSD adds aHelper role. Helper and Subscribers can flood copies with limit; such strategy canminimize the cost of the whole network, improve the success of message delivery rateand reducing the average delay.The main contributions of this paper are as follows:(1) Study the routings inDTN deeply. According to real life, find new DTN scenarios. This paper proposedPSD routing to put the Pub/Sub idea into new DTN scenarios.(2) Achieve thesimulation of PSD on ONE platform. By experiment, we find the best values of theparameters in PSD. Besides we compromise multiple performances, and comparePSD with existing algorithms, which proves the validity of the PSD.