In the past few years Wireless Mesh Networks (WMNs) have developed as a promising technology to provide flexible and low-cost broadband network services. The Expected Transmission Count (ETX) routing metric has been put forward recently as an advanced routing metric to provide high QoS for static WMNs. Most previous research in this area suggests that ETX outperforms other routing metrics in throughput and efficiency. However, it has been determined that ETX is not immune to load sensitivity and route oscillations in a single radio environment. Route oscillations refer to the situation where packet transmission switches between two or more routes due to congestion. This has the effect of degrading performance of the network, as the routing protocol may select a non optimal path. In this thesis we avoided the route oscillation problem by forcing data transmission on fixed routes. This can be implemented in the AODV (Ad hoc On-demand Distance Vector) protocol by disabling both error messages and periodic updating messages (the HELLO scheme). However, a critical factor for our approach is that ETX must determine a high quality initial route in AODV. This thesis investigates whether the ETX metric improves initial route selection in AODV compared to the HOPS metric in two representative client-server applications: the Traffic Control Network (TCN) and the Video Stream (VS) network. We evaluate the ETX and HOPS metrics in a range of scenarios which possess different link qualities and different traffic loads. We find the ETX metric greatly improves initial route selection in AODV compared to the HOPS in the network in which only single flow exists. For networks in which there are multiple simultaneous flows, ETX behaves similar to HOPS in initial route selection. Based on these results, we find the solution of route stabilization to route oscillations in the context of ETX is only useful in the single flow case. To address this problem, we propose a modified solution of repeatedly broadcasting RREQ (Route Request) packets. Simulation results show that our modified solution allows ETX to be useful in the initial route selection in both single flow and multiple simultaneous flows cases.

Ad Hoc networks are multi-hop wireless networks consisting of mobile hosts. They do not have any pre-existing network infrastructure and are characterized by constantly changing topology, limited battery power and bandwidth. Typical applications of such networks are battlefield networks, medical relief during natural calamities or disasters, conference room networking, and intra-vehicular communications. Routing packets in an ad-hoc network is a challenge because of the mobile nature of the nodes and the constantly changing topology. In ad hoc networks, each mobile node functions as a router, forwarding packets, establishing routes and helping each other in maintaining the network. A novel scalable routing protocol SLURP (Scalable Location Updated-based Routing Protocol) addresses these issues of ad hoc networks routing. The protocol is based on a location management strategy, which keeps the routing overhead to a minimum. In this thesis we compare the protocol against an existing set of multi-hop ad hoc network routing protocols that cover a range of design choices: DSDV, TORA, DSR, and AODV. We implemented SLURP in the network simulator ns-2, with the necessary wireless extensions. Experiments were run to simulate changes in network topology, number of active sources, link connectivity, and speed of motion. The difference in performance and scalability are illustrated. / Graduation date: 2003

Thesis (M.S.E.C.E)--University of Delaware, 2006. / Principal faculty advisor: Leonard J. Cimini, Jr., Electrical and Computer Engineering. Includes bibliographical references.

Thesis (MS)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: Jian Tang. Includes bibliographical references (leaves 53-54).

Thesis (M.S. in Computer Science)--Naval Postgraduate School, September 2003. / Thesis advisor(s): Geoffrey Xie, John Gibson. Includes bibliographical references (p. 75-76). Also available online.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: MAC routing protocols; ad hoc networking; MANET; performance evaluation. Includes bibliographical references (p.75-76).

Thesis (M.S.)--University of South Florida, 2003. / Title from PDF of title page. Document formatted into pages; contains 62 pages. Includes bibliographical references.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: TCP; RED; satellite; PEP; STP; performance enhancing proxy; segment caching; IP-ABR; Internet; bandwidth reservation; IP-VBR; congestion avoidance; bandwidth sharing. Includes bibliographical references (p. 98-99).

M. Tech. Electrical Engineering.. / Wireless mesh networks (WMNs) have become a better alternative for extending wireless Local Area Networks (WLANs) to provide network coverage up to the furthest of far flung rural areas. This has been implemented by using a meshed backbone network interconnecting the mesh access points (MAPs) that manage each of the WLANs, thus providing a vital mode complimentary to the wireless infrastructure-based networks. The benefits of WMN deployments, however, come with certain challenges e.g., power management. Due to the limited availability of power in typical rural areas in Africa, this dissertation presents an energy efficient localized distributed topology control algorithm to efficiently manage power consumption at the backbone of the wireless mesh networks. The goal is to extend these networks’ lifetimes, as well as improve on throughput. The focus of the project is on the application of the WMNs in rural areas in Africa and in remote urban areas where the mesh nodes are mostly powered by exhaustible power sources like wet-cells or diesel controlled power generators and hence, are considered power constrained. The proposed algorithm uses the propagation models and the concept of relay region to obtain an optimal transmission power per node. It further applies a topology management protocol framework to limit the average number of neighbours per node, which helps to reduce internodes interferences during communication. The performance of the algorithm is validated through extensive simulations in the Network Simulator (NS-2) environment. The results are further compared to those of the conventional IEEE 802.11b mesh network, without transmission power control. It is shown that with a reduction in per node transmission power via topology control it is possible to reduce the total energy consumption in the overall network. It is further shown that this reduction may lead to poor performance in capacity. Hence, it is important to ensure a proper balance in the transmit power to obtain a balance in energy efficiency as well as in throughput.

M. Tech. Electrical Engineering. / Discusses the transport of real time data in WMNs as a challenging problem. The main cause of this problem is transport layer protocols. These protocols have traditionally been used successfully for wired networks. However, their raw implementation in wireless networks has proven to be inefficient, since wireless channels are characterized by a higher Bit Error Rate (BER), Packet Loss Rate (PLR), interference, bandwidth limitations and mobility when compared to wired network channels. Thus, for the efficient transport of real time video in WMNs, transport protocols need to be adapted to be adapted to wireless networks since they were not originally developed for this application.