Buffer Scheduling Policy for Opportunitic Networks

In Delay Tolerant Networks (DTNs), the optimal use of buffer management polices can improve the network throughput. In this paper, we propose a buffer management strategy called as Message Drop Control (MDC). This technique controls the message drop by using an upper bound which is the count of buffered message at router and size of the messages. If count exceed the upper bound drop will not occurs else large size message will be dropped from queue. We examine the performance of proposed drop policy by comparing it with existing MOFO, DOA, and LIFO. The simulation results proves that MDC policy out perform well as existing ones in terms of delivery probability, message drop, overhead and buffer time average. Index Terms—buffer drop policies, Delay tolerance network, Algorithm, buffer scheduling, upper bound, large size message. —————————— a —————————— 1 I HE internet has turn out to be the most central com- ponent in connecting the devices across the world. In the past decade academic and professional researcher has proposed numerous approaches to enhance this communication architecture. The traditional networking design like TCP/IP supports end-to-end reliable trans- mission of data over a wired media. However, in some environments such as military activities, emergency oper- ations, and disaster recoveries these fixed physical confi- gurations are difficult to deploy and very expensive. Therefore, there is a need to handle the communication in such highly disrupted applications. Delay Tolerant Networks (DTNs) (2) is a challenge cri- sis networks by irregular connectivity, high latency time and lacking of end-to-end path from the source to the destination. In these environments, the transmission is carried out by "Store-Carry- Forward" paradigm, where the node stored incoming message, carries it while mov- ing and forward it when transmission opportunity arises. Hence, each node act as router and message delivery is achieved via multiple hops through dynamically con- nected mobile terminals. DTN routing protocols can be classified in two catego- ries (i) single copy and (ii) multi copy. Multi copy routing protocols (5), (6), (7) diffuse the multiple copies of each message in the network which increases the delivery probability but consumes high volume of network re- sources such as bandwidth, buffer and energy. The single copy (9), (2), (8) routing strategies forwards the single copy of message in the network thus produce less over- head on network resources. Regardless of above valued contributions in routing protocols, one of area which can influence and improve existing routing strategies is the use of message drop pol- icies. In normal conditions the drop occurs when message finds destination or its Time to live (TTL) expires. We consider the scenarios when node buffer runs out of space and it need to store new message. Recent work (11), (12), (10), (4) and (3) have proved that router performance can be improved by adopting accurate drop sequence of al- ready buffered messages. In this paper we propose buffer management policy for single copy routing protocol First contact. The tech- nique is called as Message Drop Control (MDC) and it schedules the drop sequence by utilizing the number of messages buffered at router and size of messages. To ex- hibit the performance of MDC, we assess four routing performance metrics Message drop, delivery probability overhead and buffer time averages. The proposed policy maximizes delivery probability, buffer time average and minimizes message drop and overhead as compared to existing MOFO, LIFO and DOA.