Date of Publication :24th January 2018

Abstract: Delay Tolerant Networks is a store and forward approach in which messages are delivered to the nearest potential forwarder by replicating copies of the messages. But, the various node resources such as buffer, energy, etc. are limited, thus making the DTN, a bit challenging. There exists a trade-off between the delivery ratio and overhead. Increasing the number of message copies helps to improve message delivery ratio, but also increases the overhead. On the other hand, reducing the number of message copies helps to decrease overhead while increasing message delivery delay and reducing message delivery ratio. So, the number of message copies distributed in the network has high importance. By means of controlling the number of message copies, we try to reduce overhead while maintaining the message delivery ratio in a good range (delivery ratio >90%). Since in DTN, increasing the number of message copies delivered to the destination is important, increasing the message delivery ratio as much as possible is essential for us. We use Particle Swarm Optimization to choose the appropriate number of message copies. First, we limited the number of copies of the messages being transferred to 54,000 which is lesser than the original number of message replicas by five-folds. We manage to keep the value of delivery probability to 94% of the actual value, even after implementing PSODTN. Then, we implemented the prioritization of the messages so that the messages of high priority get transferred first.

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