Dr Timothy Aubrey

Smith, D.B. & Aubrey, T.A. 2005, 'Differential unitary space-time superset modulation', European Transactions On Telecommunications, vol. 16, no. 4, pp. 303-307.
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A simple framework is presented for transmission of constellation supersets, starting from a consideration of differential diagonal unitary space-time modulation (DUSTM), called DUST superset modulation (DUSTSM). The need for extension of previously stat

Godfrey, J.E., Aubrey, T.A., Crosthwaite, C. & King, R. 2010, 'Who leaves and when do they go? Retention and attrition in engineering education', ASEE/IEEE Frontiers in Education Conference, Arlington, Virginia, USA, October 2010 in ASEE/IEEE Frontiers in Education Conference - Celebrating 40 Years of Innovation - Proceedings, ed FIE Steering Committee, Stipes Publishing LLC, USA, pp. F3E-1-F3E-6.
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At a time of high demand for engineering graduates, the mean graduation completion rate of engineering undergraduates in Australia has been identified as approximately 54% (with considerable variation across institutions and sectors). This paper reports on the initial results of cohort analyses undertaken at two engineering degree granting institutions as part of a multi institutional project seeking to understand and reduce student attrition from engineering degrees across Australia. Both institutions have a predominantly urban student population and location, but whilst one offers a conventional four year degree the other integrates two semesters of internship into its degree structure. A cohort analysis procedure, tracking pathways to completion or non-completion of the degree, applicable across diverse institutions, was piloted. Attributes such as gender, academic background, full or part time study, engineering major and student maturity were identified for each member of the cohort. The patterns revealed by these fine grained cohort analyses challenged some anecdotal perceptions and provided evidence of the inadequate nature of generalizations around attrition statistics, and the need for institutional context and culture to be considered.

Godfrey, J.E., Aubrey, T.A. & King, R. 2010, 'Who leaves and who stays? Retention and attrition in Engineering Education', Engineering Education Conference, Aston University, UK, July 2010 in Engineering Education 2010 (EE2010): Inspiring the next generation of engineers, ed Engineering Subject Centre Staff, The Higher Education Academy Engineering Subject Centre, UK, pp. 1-13.
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At a time of high demand for engineering graduates, the mean graduation completion rate of engineering undergraduates in Australia has been identified as approximately 54% (with considerable variation across institutions and sectors). This proportion of non- completions has been viewed as an excessive loss to the qualified workforce of Australia. Broad brush, governmentcollected statistics do not, however, provide the level of detail required to understand who leaves, when and why they leave, and where they go. This paper reports on a pilot study undertaken to precede and inform final decisions on research design and methodology for a multi institutional project seeking to understand and reduce student attrition from engineering degrees across Australia. The aim of the project is to produce guidelines on curriculum formulation and delivery strategies to reduce attrition in engineering programs while meeting outcomes. The pilot study was conducted at an institution which has a relatively diverse range of students, a high proportion of whom study part time, and engineering degree structures incorporating traditional and internship-based degrees. Results from a cohort analysis, tracking pathways to completion or noncompletion of the degree for the cohorts from two specific entry years will be presented. From this analysis, groups of students who 'persisted over long periods', 'switched to another degree' or 'withdrew from the university' were identified and interviewed. Their experiences and stories, were an essential ingredient for a better understanding of the dynamics of retention/attrition and actors which required further questioning before proceeding with the multi institutional study.

Lawrence, E.M., Loke, L., Raban, R., Brookes, W.C. & Aubrey, T.A. 2009, 'Towards an Understanding of Collaboration in Teaching Technology Subjects in an Amalgamated Faculty of Engineering and Information Technology', International Conference on Mobile, Hybrid, and On-Line Learning, Cancun, Mexico, February 2009 in International Conference on Mobile, Hybrid, and On-line Learning EL & ML 2009, ed Lawrence, E; Loke, L; Raban, R; Brookes, W; Aubrey, T, IEEE Computer Society Conference Publications, Cancun, Mexico, pp. 47-52.
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The paper sets out a collaborative approach for teaching technology subjects. It Illustrates the benefits of this approach over the single academic owning a particular subject. The paper presents preliminary findings from interviews with academics in a newly combined Faculty of Engineering and Information Technology. It concludes by pointing the way to the future of htis funded research project.

Lu, Z., Kadi, A. & Aubrey, T.A. 2009, 'A CME Based Channel Estimation Approach for MIMO-OFDM Systems', International Conference on Wireless Communications, Networking and Mobile Computing, Beijing, China, September 2009 in Proceedings of the 5th International Conference on Wireless communications, networking and mobile computing, ed un aware, IEEE Press, Piscataway, USA, pp. 783-786.
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A pilot-assisted, conditional model-order estimation (CME) based channel estimation algorithm is presented. The algorithm is proposed for MIMO-OFDM systems and can detect both channel frequency responses and number of multi-path taps. In addition, the modified CME estimator is also verified its capacity in determining the nonzero taps. The performance of the proposed approach is compared to the popular minimum description length (MDL) algorithm for estimation of the number of channel paths, by means of simulation in the context of a 2x2 MIMO-OFDM transceiver system. Result indicates that the new algorithm is superior in channel order estimation to the MDL algorithm in MMO-OFDM system over a noisy frequency selective fading channel.

Lu, Z., Kadi, A. & Aubrey, T.A. 2009, 'A hybrid CME-LS channel estimation approach for broadband MIMO-OFDM systems', International Symposium on Communications and Information Technologies, Incheon, Korea, September 2009 in Symposium on Communications and Information Technology, 2009. ISCIT 2009. 9th International, ed Yeong Min Jang (Kookmin University), IEEE, Piscataway, pp. 313-318.
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A channel estimation approach yielding both channel gains and the number of multi-paths is presented. The algorithm is based on a variation of conditional model order estimation (CME), and is proposed for MIMO-OFDM systems. The CME based estimator is shown to be viable in both fixed and mobile broadband MIMO-OFDM wireless applications, and takes advantage of determining the nonzero taps as well. The performance of the approach is compared to the popular minimum description length (MDL) algorithm for estimation of the number of channel paths, by means of simulation in the context of a 2times2 MIMO-OFDM transceiver system. Results indicate that the new algorithm is superior in channel order estimation to the MDL algorithm in MMO-OFDM system over a noisy frequency selective fading channel.

Smart, K. & Aubrey, T.A. 2009, 'Evaluation of a magnetic near field scanner', Asia-Pacific Microwave Conference, Singapore, December 2009 in Microwave Conference, 2009. APMC 2009. Asia Pacific, ed Joshua Le-Wei LI, National University of Singapore, Singapore, IEEE, Piscataway, USA, pp. 413-416.
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Traditionally, the measurement of antenna performance often required significant capital outlay on anechoic test chambers and associated test equipment. A novel device manufactured by Canadian company Emscan that can perform some of these measurements in a bench-top environment may offer a solution. A study was undertaken into the performance of the Emscan near-field scanner. Comparisons with measurements taken in anechoic chamber and theoretical models using CST microwave studio are used in the evaluation of the scanner as well as measurements of repeatability and accuracy.

Aubrey, T.A. & Aboura, K. 2008, 'Bandwidth Utilisation for volume-to-volume UWB MIMO Communications', International Symposium on Wireless Pervasive Computing, Santorini, Greece, May 2008 in Proceedings of 3rd International Symposium on Wireless Pervasive Computing (ISWPC 2008), ed Stouraitis, T etal, IEEE, US, pp. 88-92.
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Previous studies have investigated communications between regions of space and have considered the effect of antenna volume in determining the theoretical capacity of multiple-input multiple-output (MIMO) communications systems. In this paper the effects of antenna 1volume on available bandwidth for MIMO systems is considered. It is demonstrated that while higher order modal connections can be established even for small antennas that a fundamental limitation on bandwidth exists. This limitation becomes important for ultra-wide band (UWB) communications systems.

Smith, D.B., Abhayapala, T.D. & Aubrey, T.A. 2004, 'A generalised (M,NR) MIMO Rayleigh channel model for non-isotropic scatterer distributions.', Workshop on the Application of Radio Science, Hobart, Australia, February 2004 in Proceedings of Workshop on the Application of Radio Science, (WARS) 2004, ed Proceedings Editor - Phil Wilkinson Commission C Editor - Robin Braun (Commission C) et al, National Committee for Radio Science, Hobart, Australia, pp. 1-6.
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