International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / There are a number of telemetry applications where it would be helpful to have networks of sensors that could autonomously discover their connectivity, and dynamically reconfigure themselves during use. A number of research groups have developed wireless ad-hoc sensor network systems. This paper reviews the state-of-the-art in wireless ad-hoc networks, examining the features, assumptions, limitations and unique attributes of some of the more popular solutions to this problem.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Sensor technology is continually advancing to meet demands of a wide range of potential applications. Many of these applications could be better served by distributed sensing than by traditional centralized sensing. To support these emerging applications, it is important to design and develop a unified framework for communication and network infrastructure capable of supporting various sensing functions. A research prototype operating in the 915 MHz Industrial, Scientific, and Medical band (ISM band) has been developed as potentially the core component of this infrastructure. In this paper, we will present the design and optimization of the system, data processing procedures, system parameters, network protocols, and experimental results.

Research in mobile ad-hoc networks has focused on situations in which nodes have no control over their movements. We investigate an important but overlooked domain in which nodes do have control over their movements. Reinforcement learning methods can be used to control both packet routing decisions and node mobility, dramatically improving the connectivity of the network. We first motivate the problem by presenting theoretical bounds for the connectivity improvement of partially mobile networks and then present superior empirical results under a variety of different scenarios in which the mobile nodes in our ad-hoc network are embedded with adaptive routing policies and learned movement policies.

Research in mobile ad-hoc networks has focused on situations in whichnodes have no control over their movements. We investigate animportant but overlooked domain in which nodes do have controlover their movements. Reinforcement learning methods can be used tocontrol both packet routing decisions and node mobility, dramaticallyimproving the connectivity of the network. We first motivate theproblem by presenting theoretical bounds for the connectivityimprovement of partially mobile networks and then present superiorempirical results under a variety of different scenarios in which themobile nodes in our ad-hoc network are embedded with adaptive routingpolicies and learned movement policies.

No / A method and apparatus are provided for ad hoc networking over a universal mobile telecommunications system (UMTS) . In the method, if user equipment (40A) (such as a mobile phone) is not within normal cell coverage (20) , then in an uplink procedure a message which would normally have not be able to be transmitted directly from the User Equipment (40A) to a Base Station (10) is instead forwarded towards the Base Station (10) via one or more intermediate User Equipments (40B) . In the method, the user equipment (40A) is arranged to synchronise itself with the Base Station (10) to acquire timeslot and frame synchronisations and thence perform probing activities to build up a list of neighbouring User Equipments. From this list and power and signal to interference calculations the user equipment (40A) is able to work out the relative positions of its neighbours with respect to the Base Station and itself and come to a routing decision for forwarding its message towards the Base Station.

ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / Spectrum allocation in wireless communication and telemetry systems of the future may be performed in a dynamic and distributed manner, as opposed to static centralized regulations currently in place. This paper surveys a new area of research in the communications field known as cognitive radio which will allow dynamic sharing of spectral bands. An introduction to cognitive radio, a review of existing research results, and discussion of open problems in the area is provided.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Ad hoc networking protocols enable the formation of self-organizing networks with automatic selfhealing operation in dynamic environments. There are a number of existing or planned ad hoc implementations and a body of research on protocols and performance. Ad Hoc technologies promise significant impact in future communications architectures. This paper presents a general overview of ad hoc networking and presents specific examples, including a recent implementation of a prototype ad hoc networked sensor system. The protocols used have unique characteristics derived by tailoring particular protocols to the specific application requirements. The potential relevance of ad hoc networking to possible telemetry applications is discussed.

<p>This thesis covers the issue of securing ad hoc networks. Such networks exhibit a number of characteristics that make such a task challenging. One of the major challenges is that ad hoc networks typically lack a fixed infrastructure both in form of physical infrastructure such as routers, servers and stable communication links and in the form of an organizational or administrative infrastructure. Another difficulty lies in the highly dynamic nature of ad hoc networks since new nodes can join and leave the network at any time. </p><p>The major problem in providing security services in such infrastructure less networks is how to manage the cryptographic keys that are needed. In order to design practical and efficient key management systems it is necessary to understand the characteristics of ad hoc networks and why traditional key management systems cannot be used. These issues are covered and the thesis also provides a summary of those key management solutions that have been proposed in the research literature so far.</p>

This thesis covers the issue of securing ad hoc networks. Such networks exhibit a number of characteristics that make such a task challenging. One of the major challenges is that ad hoc networks typically lack a fixed infrastructure both in form of physical infrastructure such as routers, servers and stable communication links and in the form of an organizational or administrative infrastructure. Another difficulty lies in the highly dynamic nature of ad hoc networks since new nodes can join and leave the network at any time. The major problem in providing security services in such infrastructure less networks is how to manage the cryptographic keys that are needed. In order to design practical and efficient key management systems it is necessary to understand the characteristics of ad hoc networks and why traditional key management systems cannot be used. These issues are covered and the thesis also provides a summary of those key management solutions that have been proposed in the research literature so far.

Physical indoor wireless network testbeds as well as outdoor wireless testbeds have the potential to accelerate the pace of research in the field of wireless ad hoc and mesh networking. They form part of a critical chain of steps needed to develop and test ad hoc networking protocols from concept to eventual uptake by industry. Current research in this area makes use of simulations or mathematical models which oversimplify the physical and Medium Access Control layer. In Africa specifically, wireless mesh networking has the potential to make a substantial impact on the lack of telecommunications infrastructure across the continent. A combination of good theoretical analysis, indoor test facilities and rural testbeds forms a perfect suite to carry out meaningful research in the field. A 7x7 wireless grid of closely spaced computers was constructed, making use of highly attenuated 802.11 radios running in ad hoc mode. Modelling and analysis revealed that a suitably attenuated environment was created with variation in signal strength between node pairs following a Gaussian distribution. This emulates a real outdoor network with normal signal propagation issues such as multi-path fading and lack of Fresnel zone clearance. This testbed was then used to evaluate 3 popular MANET ad hoc routing protocols, namely AODV, DYMO and OLSR. OLSR was tested with the standard hysteresis routing metric as well as the ETX routing metric. OLSR showed the best performance in terms of average throughput and packet loss for a medium size (21 node) and large (49 node) mesh network, with the hysteresis routing metric performing best in large networks and ETX performing best in medium sized networks. DYMO also performed very well, considering its low routing overhead, exhibiting the least amount of delay in a large mesh network (49 nodes). The AODV protocol showed the weakest performance in the grid with close to 60% of possible link pairs achieving no route in a 49-node grid. However, it did present the least amount of routing overhead compared with other routing protocols. Finally, a medium-sized rural mesh network testbed consisting of 9 nodes was built in a mountainous area of about 15 square kilometers around an AIDS clinic using the OLSR routing protocol with ETX as the routing metric. The network provided a good service to the satellite-based Internet with throughput rates ranging between 300 kbps for 4 hops and 11000 kbps for 1 hop and an average throughput rate of 2324 kbps. To encourage fair sharing of Internet connectivity, features were installed to limit each user to 40 MB/month of free Internet traffic. A local web server offers cached pages of Wikipedia and Linux repositories to reduce the need for Internet access. VoIP services were also installed between clinic infrastructure to reduce the the need for making expensive GSM calls. It was shown that a mesh network of this size provides a very satisfactory level of broadband service for users accessing a satellite-based Internet facility as well as local VoIP services. / Dissertation (MEng)--University of Pretoria, 2009. / Electrical, Electronic and Computer Engineering / unrestricted