Adaptive topologies: improving wireless networks through the use of additional nodes and power control.
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Date
2014
Authors
Hunjet, Robert Anthony
Editors
Advisors
Sorell, Matthew James
Coyle, Andrew James
Coyle, Andrew James
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Thesis
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Abstract
The work presented in this thesis shows that shared spectrum wireless networks can be enhanced through the use of additional nodes and power control. Network improvement is demonstrated in three key areas: connectivity, capacity and power efficiency. It is also shown that the techniques developed to increase network capacity and power efficiency have a positive effect on the security of the network. Mobile ad hoc networks are the specific focus of the work, but the results are applicable to both wireless sensor networks and shared spectrum wireless infrastructure based networks. This thesis demonstrates how additional nodes may be used in mobile wireless networks to maintain connectivity by specifically targeting bridges and articulation points. It then takes a graph theoretical approach to networking, with the assumption that lowering interference increases network capacity, to show that additional nodes combined with power control can be used to simultaneously increase the capacity and power efficiency of wireless networks. An implementation of a novel method to generate all possible transmission states under a Request To Send (RTS) / Clear To Send (CTS) scheme is used in the creation of a repeatable metric, Uniform Average Network Capacity (UANC). This metric describes the capacity that can be held within a network, and is suitable for comparing one network to another, enabling its use in optimisations. UANC is used in a multi objective cross entropy optimisation of capacity and power efficiency to create Pareto optimal sets of viable network topologies which exhibit high capacity and low power use. The work presented then derives the conditions under which n simultaneous transmissions are beneficial to capacity. This leads to the definition of a separation multiplier, i.e., the ratio of distances between receivers and between senders and their receivers, which is used to create wireless networks which exhibit high UANC. The separation multiplier is then utilised in existing networks, where topologies are altered through the modification of transmission powers and the use of additional nodes, to create higher capacity networks, showing that additional nodes can benefit network capacity. This technique has the added benefit of increasing network power efficiency. A modification to the RTS/CTS protocol which uses the separation multiplier is then presented. The new scheme has the effect of allowing only beneficial simultaneous transmissions to occur. It is shown through simulation that this approach increases network capacity. Networks which implement the capacity and power efficiency enhancing measures presented are shown to exhibit increased security, in that the lowering of transmission power and allowance of multiple transmissions within the network reduces the distance at which trans- missions can be detected and decoded. Finally, an implementation of the overall knowledge gained through the thesis is presented, augmenting existing networks with additional nodes and power control to create bi-connected, power efficient and high capacity networks.
School/Discipline
School of Electrical and Electronic Engineering
Dissertation Note
Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2014
Provenance
This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals