A New Queuing Policy for Delay Tolerant Networks

Recently there has been much research activity in the area of Delay Tolerant Networks (DTNs). Routing is one of the key components in the DTN architecture. DTNs operate with the principle of store, carry and forward. According to this principle, a node may store a message in its buffer and carry it along, until it can forward it further. The message transmission occurs only when nodes come into the communication range of each other. Mobility of the nodes shortens the contact duration. It may not be possible for a node to transmit all messages it has during the available period of contact. Therefore decision has to be made on the order of messages to be transmitted. Similarly, in order to cope up with long disconnections, messages are buffered for a long period of time. Once the buffer capacity is reached, nodes must decide on the message to be dropped. Thus a new queuing policy has been proposed in this paper which takes care of both. The proposed policy considers the class of service and the expiration time for making such decisions. The Delay Tolerant Networks with random behavior is considered in this paper. Therefore epidemic routing which is the better choice for such network has been used for evaluation. The simulation results show that the new policy outperforms existing policy in terms of delivery ratio and delivery latency with preferential delivery.