Buffer Management for Preferential Delivery in Opportunistic Delay Tolerant Networks

Delay Tolerant Networks (DTN) present many challenges that are not present in traditional networks. Many stem from the need to deal with disconnections which directly impacts routing and forwarding. However as these networks enable communication between wide range of devices, there are secondary problems that routing strategies may need to take care of such as to deal with limited resources like buffer, bandwidth, power. Most of the routing protocols in DTN assume that the buffer size as infinite which is not the case in reality. In resource constrained environment, buffers will run out of capacity at certain point of time. Moreover due to mobility of the nodes and limited bandwidth, it is not possible to transmit all messages a node has during the short available period of contact. Consequently an efficient buffer management policy is required under resource constrained DTNs. Further, DTNs can be used to support several asynchronous applications simultaneously. Each application may have different priority. For example, an emergency alert in monitoring application is more important than the regular data. Such environment stimulates the need to introduce priority to messages. Therefore in this paper, a policy is proposed which performs buffer management with prioritization. The proposed approach with epidemic routing is evaluated through simulation and compared with other policies. It is shown that the proposed approach results in performance improvement to epidemic routing with preferential delivery.