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Title: An OFDMA-based data extraction protocol for wireless sensor networks
Author: MacEwen, Neil C.
ISNI:       0000 0004 2679 5921
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2009
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The field of Wireless Sensor Networks (WSNs) includes a wide range of application areas and presents many different requirements on network and physical layer design and implementation. The Speckled Computing Consortium (SCC) is investigating one form of WSN where each node is severely constrained in size and energy. With this in mind, physical layer architectures have to be carefully designed to be as efficient as possible. The Orient-2 is a posture tracking system developed within the SCC which uses small, battery-powered nodes to track the movement of a body and relay the information to a central location. Off-the-shelf components limit the manner in which data are extracted, and result in the system being constrained in terms of the number of nodes supported, radio bit rate and update rate. These constraints provide motivation for the development of an application-driven solution which allows these limitations to be relaxed. A data extraction protocol is proposed which is based on Orthogonal Frequency Division Multiple Access (OFDMA). Although OFDMA allows a receiver to elegantly receive multiple transmissions in parallel, it requires accurate time and frequency synchronisation between users. Standard offset management techniques are overly complex for the simple nodes desired in the Orient-2 system, and as such a systemspecific solution is developed. In the proposed protocol, time offsets are managed using receiver-initiated transmissions which result in the offsets being reduced to manageable levels. Subcarrier modulation, frequency offset estimation and compensation are combined in a novel all-digital transmitter architecture which minimises the effects of the frequency offsets and associated performance loss. Finally, the performance of the frequency estimation, compensation and subcarrier generation architecture is analysed in detail in order to find the minimum complexity node implementation which satisfies the performance requirements of the Orient-2 system.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral