Evaluation of Transport Layer Protocols for wireless multi-hop networks

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University of Zululand
Wireless Multi-hop Network (WMN) is a collection of wireless nodes that dynamically form a network without an infrastructure support. It is a promising technology for several interesting applications such as broadband home networking, community and neighborhood networks, coordinated management, intelligent transportation system. WMN is gaining significant attention as a feasible way for Internet providers (ISPs) and other end-users to establish robust and reliable wireless broadband service access at a reasonable cost. Quality of Service (QoS) requirements and network services provided by WMNs vary from reliable file transfer to real-time. Multiple protocols for QoS such as routing protocols, topology controls, medium access control (MAC) and transport layer protocol (TLP) have been proposed for WMNs. The focus of this study is on the transport layer protocol (TLP) as the mechanism provides QoS in WMNs. Performance of Traditional TLP (such as TCP) deteriorates in WMNs. Traditional TLP designed for wired network and assumes that all packets losses are due to network congestion, whereas in WMNs congestion is not always the cause of packet losses. As result, several TLPs proposed to tailor for traditional TLPs in WMNs. Despite the large number of TLPs proposed for WMNs, it is not clear which TLP performs better for WMNs, since they are not compared in a consistent manner. Therefore, we have designed literature analysis framework which enabled us to categorize the TLPs into four classes. This framework was also used to select the TLPs for evaluation. We selected eight (two from each category) TLPs plus two traditional TLPs (i.e. TCP and UDP). Using simulation, we evaluated and compared the performance of the selected TLPs in WMN scenarios. In our evaluations and comparisons of the selected TLPs, the QoS performance metrics such as throughput, delay, and packet delivery ratio were considered. Two congestion and reliability related performance metric namely: number of packet retransmission (PR) and round trip time (RTT) were also considered. These performance metrics were varied with network size, number of flows, distance between nodes and simulation time. The evaluations and comparisons studies enabled us to choose TLP suitable for WMNs. Our results show that, among the four TLP categories, Hybrid performs better than all TLP categories. Finally, we made recommendations for an ideal TLP applicable to WMNs that would improve efficiency of the TLP over WMNs.
A thesis submitted to the Faculty of Science and Agriculture in fulfilment of the requirements for the degree of Master of Science in Computer Science in the Department of Computer Science at the University of Zululand, South Africa, 2014
Wireless Multi-hop Network --infrastructure support --transport layer protocols