Improving delay tolerant network buffer management approach for rural area’s health professionals’ information exchange syste

Abstract

Delay-tolerant networks (DTNs) are mobile networks in the field of wireless network which are emphasized to provide end-to-end connectivity in the areas where the networks are not reliable and often susceptible to interferences. Despite the rapid advancement of communication technology, there are still rural places that are not connected to the Internet. Health information exchange between rural area and the urban areas still hampered by in adequate telecommunication infrastructures coverage, intermittent connectivity and absence of end-to-end connectivity. The term Delay Tolerant Network (DTN) is invented to bridged communication gaps that have not been connected to the Internet. In current TCP/IP technology communication is possible only when end-to-end path is available. As a result, the usual Internet and TCP/IP network cannot be valid for some hard environments which are characterized by lack of direct path between nodes, lot of power outages and intermittent connectivity. In this work, the researcher investigated the performance of various delay tolerant network routing protocols and selected MaxProp which is convenient for the proposed framework. Most routing algorithm of delay tolerant network assume the nodes buffer space as unlimited but, it is not the case in reality. As flooding-based routing relies on buffer to have a copy of every message at every node, buffer space has substantial impact on delivery probability. The existing buffer management policies compute in biased way, directed by a single parameter in a random manner while other relevant parameters are completely neglected, resulting in an inability to make a reasonable selection. Therefore, the researcher proposed a reasonable buffer management approach on the situations where there is a short contact duration, limited bandwidth and buffer. The proposed buffer management approach improves buffer availability by implementing three buffer management strategies: scheduling, dropping, and clearing buffers entirely for computing purposes, using three parameters: message type, hop count and time to live. The performance of proposed approach is validated through simulation by using opportunistic Network Environment (ONE) simulator. They were analyzed on three metrics, namely delivery probability, average latency and overhead ratio. The simulation results collected in this thesis shows that when the nodes buffer get constrained the proposed method MaxProp Routing based on Message Type Priority (MPRMTP) perform better than the existing buffer management policy by increasing the message delivery quality and decreasing overhead ratio. However, when there is sufficient buffer space, both MaxProp, and MPRMTP shows comparable performance