SAWBD: social aware weight based buffer management policy for DTNs

Abstract

The term delay-tolerant network (DTN) is coined to describe and include all types of long-delay, disconnected, disrupted or intermittently-connected networks. So, in such network, communication is established with the help of encounter opportunities between nodes and those nodes follow store- carry and forward approach to achieve data delivery. In this approach, each node stores the messages in their buffers until they encounter another node and also to achieve a high delivery ratio most of DTN routing transmits multiple copies of messages. But the combination of long term storage and multiple copies of message transmission in this process impose greater transmission overhead and buffer occupancy. Most of the previous efforts on improving the performance of routing do not consider the issue of resource limitations like buffer and bandwidth. However, hand held devices which are having limited storage and bandwidth are used in many of DTN applications. Therefore, buffer management policies have a direct impact on routing performance of DTNs routing. Basing on this point, in this paper a Social aware wait based buffer management policy has been proposed in the situations where there is short contact duration, limited bandwidth and buffer. Very little attention has been directed towards applying the social characteristics of the users to mitigate the congestion in DTN. This paper presents a buffer management strategy for DTNs that takes into account a value associated with the social relationship strength among the users. In addition to the social relationship between nodes we also used a weight criterion to schedule messages to be drooped and/or transmitted based on message properties. We evaluated this policy with Epidemic routing algorithms. By means of a thoroughly planned set of steady-state simulation experiments with two real world traces, we found that the proposed scheme has outperformed the DCB, HBD & MOFO policies in terms of delivery rate & delivery delay. When compared to DCB in terms of delivery rate, in different buffer size (20M, 40M, 60M, and 80M) SAWBD has a delivery rate of (55%, 63%, 77%, and 84%) whereas DCB has (50%, 59%, 64%, and 78%) and when compared to HBD, HBD has (42%, 45%, 57% and 60%) delivery rate. This shows that the proposed policy has better performance than those policies used in our simulation test.