Measurement, modelling and capacity analysis for novel, fixed multi-user single-antenna MIMO-OFDM system, in rural environments

High-speed broadband internet access is widely recognised as a catalyst to social and economic development. However, the provision of broadband Internet services with the existing solutions to rural population, scattered over an extensive geographical area, remains both an economic and technical challenge. As a feasible solution, the Commonwealth Scientific and Industrial Research Organization (CSIRO) proposed a highly spectrally efficient, innovative and cost-effective fixed wireless broadband access technology, which uses analogue TV frequency spectrum and Multi-User MIMO (MUMIMO) technology with Orthogonal-Frequency-Division-Multiplexing (OFDM). MIMO systems have emerged as a promising solution for the increasing demand of higher data rates, better quality of service, and higher network capacity. However, the performance of MIMO systems can be significantly affected by different types of propagation environments e.g., indoor, outdoor urban, or outdoor rural and operating frequencies. For instance, large spectral efficiencies associated with MIMO systems, which assume a rich scattering environment in urban environments, may not be valid for all propagation environments, such as outdoor rural environments, due to the presence of less scatterer densities. Since this is the first time a MU-MIMO-OFDM fixed broadband wireless access solution is deployed in a rural environment, questions from both theoretical and practical standpoints arise; For example, what capacity gains are available for the proposed solution under realistic rural propagation conditions?. Currently, no comprehensive channel measurement and capacity analysis results are available for MU-MIMO-OFDM fixed broadband wireless access systems which employ large scale multiple antennas at the Access Point (AP) and analogue TV frequency spectrum in rural environments. Moreover, according to the literature, no deterministic MU-MIMO channel models exist that define rural wireless channels by accounting for terrain effects. This thesis fills the aforementioned knowledge gaps with channel measurements, channel modeling and comprehensive capacity analysis for MU-MIMO-OFDM fixed wireless broadband access systems in rural environments. For the first time, channel measurements were conducted in a rural farmland near Smithton, Tasmania using CSIRO's broadband wireless access solution. A novel deterministic MU-MIMO-OFDM channel model, which can be used for accurate performance prediction of rural MUMIMO channels with dominant Line-of-Sight (LoS) paths, was developed under this research. Results show that the proposed solution can achieve 43.7 bits/s/Hz at a Signal-to- Noise Ratio (SNR) of 20 dB in rural environments. Based on channel measurement results, this thesis verifies that the deterministic channel model accurately predicts channel capacity in rural environments with a Root Mean Square (RMS) error of 0.18 bits/s/Hz. Moreover, this study presents a comprehensive capacity analysis of rural MU-MIMOOFDM channels using experimental, simulated and theoretical models. Based on the validated deterministic model, further investigations on channel capacity and the eects of capacity variation, with different user distribution angles (θ) around the AP, were analysed. For instance, when SNR = 20dB, the capacity increases from 15.5 bits/s/Hz to 43.7 bits/s/Hz as θ increases from 10° to 360°. Strategies to mitigate these capacity degradation effects are also presented by employing a suitable user grouping method. Outcomes of this thesis have already been used by CSIRO scientists to determine optimum user distribution angles around the AP, and are of great significance for researchers and MU-MUMO-OFDM system developers to understand the advantages and potential capacity gains of MU-MIMO systems in rural environments. Also, results of this study are useful to further improve the performance of MU-MIMO-OFDM systems in rural environments. Ultimately, this knowledge contribution will be useful in delivering efficient, cost-effective high-speed wireless broadband systems that are tailor-made for rural environments, thus, improving the quality of life and economic prosperity of rural populations.

Quantitative ultrasound computed tomography imaging of PAGAT radiation dosimetry gel

This research developed and scientifically validated a new ultrasound transmission computed tomography system with the aim of quantitative assessment of a polymer gel dosimeter including dose response verification of ultrasonic parameters of attenuation, velocity and broadband ultrasound attenuation (BUA). This work was the first to investigate and report ultrasound frequency dependent attenuation in a gel dosimeter, demonstrating a dose dependence.

Channel tracking in SDMA-based multi-user MIMO-OFDM communications systems

Capacity of current and future high data rate wireless communications depend significantly on how well changes in the wireless channel are predicted and tracked. Generally, this can be estimated by transmitting known symbols. However, this increases overheads if the channel varies over time. Given today’s bandwidth demand and the increased necessity for mobile wireless devices, the contributions of this research are very significant. This study has developed a novel and efficient channel tracking algorithm that can recursively update the channel estimation for wireless broadband communications reducing overheads, therefore increasing the speed of wireless communication systems.

Australian Research to Encourage School Students’ Positive Use of Technology to Reduce Cyberbullying

Information and Communications Technology (ICT) has spread rapidly in Australia. Mobile phones, which increasingly have advanced capabilities including Internet access, mobile television and multimedia storage, are owned by 22% of Australian children aged 9-11 years and 73% of those aged 12-14 years (Australian Bureau of Statistics, 2012b), as well as by over 90% of Australians aged 15 years and over(Australian Communications and Media Authority (ACMA), 2010). Nearly 80% of Australian households have access to the Internet and 73% have a broadband Internet connection, ensuring that Internet access is typically reliable and high-speed (Australian Bureau of Statistics, 2012a). Ninety percent of Australian children aged 5-14 years (comprising 79% of 5-8 year olds; 96% of 9-11 year olds; and 98% of 12-14 year olds) reported having accessed the Internet during 2011-2012, a significant increase from 79% in 2008-2009 (Australian Bureau of Statistics, 2012b). Approximately 90% of 5-14 year olds have accessed the Internet both from home and from school, with close to 49% accessing the Internet from other places (Australian Bureau of Statistics, 2012b). Young people often make use of borrowed Internet access (e.g. in friends’ homes), commercial access (e.g. cybercafés), public access (e.g. libraries), and mobile device access in areas offering free Wi-Fi (Lim, 2009).

The local library across the digital and physical city : opportunities for economic development

This paper considers the role of the public library as a community hub, engagement space, and entrepreneurial incubator in the context of the city, city governance, and local government planning. It considers this role from the perspective of library experts and their future visions for libraries in a networked knowledge economy. Public libraries (often operated by or on behalf of local governments) potentially play a pivotal role for local governments in positioning communities within the global digital network. Fourteen qualitative interviews with library experts informed the study which investigates how the relationship between digital technology and the physical library space can potentially support the community to develop innovative, collaborative environments for transitioning to a digital future. The study found that libraries can capitalise on their position as community hubs for two purposes: first, to build vibrant community networks and forge economic links across urban localities; and second, to cross the digital divide and act as places of innovation and lifelong learning. Libraries provide a specific combination of community and technology spaces and have significant tangible connection points in the digital age. The paper further discusses the potential benefits for libraries in using ICT networks and infrastructure, such as the National Broadband Network in Australia. These networks could facilitate greater use of library assets and community knowledge, which, in turn, could assist knowledge economies and regional prosperity.

'Water view' from cyberspace : building resilient communities by identifying water risks

The perceived desirability of water views continues to lead to increasing numbers relocating to coastal regions. Proximity to coastal water brings with it unique risks from rising sea levels; however, water can present a risk in any area, whether or not you have water views. Recent Australian and international disasters show that even inland populations not located in traditional flood areas are not immune from water risks. The author examines the nature of these risks and shows how the internet can be used as a tool in identifying risk areas. The author also highlights the need to ensure accuracy of the data for valuation and planning purposes and identifies flaws in the current data provision.

Synthesis, photophysical and electrochemical properties of aza-boron-diquinomethene complexes

A series of aza-boron-diquinomethene (aza-BODIQU) complexes with different aryl-substituents (B1–B6) were synthesized and characterized. Their photophysical properties were investigated systematically via spectroscopic and theoretical methods. All complexes exhibit strong 1π–π* absorption bands and intense fluorescent emission bands in the visible spectral region at room temperature. The fluorescence spectra in solution show the mirror image features of the S0→S1 absorption bands, which can be assigned to the 1π–π*/1ICT (intramolecular charge transfer) emitting states. Except for B6, all complexes exhibit high photoluminescence quantum yields (ΦPL = 0.47–0.93). The spectroscopic studies and theoretical calculations indicate that the photophysical properties of these aza-BODIQUs can be tuned by the appended aryl-substituents, which would be useful for rational design of boron–fluorine complexes with high emission quantum yield for organic light-emitting applications.

A deconvolution method for deriving the transit time spectrum for ultrasound propagation through cancellous bone replica models

The acceptance of broadband ultrasound attenuation for the assessment of osteoporosis suffers from a limited understanding of ultrasound wave propagation through cancellous bone. It has recently been proposed that the ultrasound wave propagation can be described by a concept of parallel sonic rays. This concept approximates the detected transmission signal to be the superposition of all sonic rays that travel directly from transmitting to receiving transducer. The transit time of each ray is defined by the proportion of bone and marrow propagated. An ultrasound transit time spectrum describes the proportion of sonic rays having a particular transit time, effectively describing lateral inhomogeneity of transit times over the surface of the receiving ultrasound transducer. The aim of this study was to provide a proof of concept that a transit time spectrum may be derived from digital deconvolution of input and output ultrasound signals. We have applied the active-set method deconvolution algorithm to determine the ultrasound transit time spectra in the three orthogonal directions of four cancellous bone replica samples and have compared experimental data with the prediction from the computer simulation. The agreement between experimental and predicted ultrasound transit time spectrum analyses derived from Bland–Altman analysis ranged from 92% to 99%, thereby supporting the concept of parallel sonic rays for ultrasound propagation in cancellous bone. In addition to further validation of the parallel sonic ray concept, this technique offers the opportunity to consider quantitative characterisation of the material and structural properties of cancellous bone, not previously available utilising ultrasound.

New media [Fourth Edition]

This is the fourth edition of New Media: An Introduction, with the previous editions being published by Oxford University Press in 2002, 2005 and 2008. As the first edition of the book published in the 2010s, every chapter has been comprehensively revised, and there are new chapters on: • Online News and the Future of Journalism (Chapter 7) • New Media and the Transformation of Higher Education (Chapter 10) • Online Activism and Networked Politics (Chapter 12). It has retained popular features of the third edition, including the twenty key concepts in new media (Chapter 2) and illustrative case studies to assist with teaching new media. The case studies in the book cover: the global internet; Wikipedia; transmedia storytelling; Media Studies 2.0; the games industry and exploitation; video games and violence; WikiLeaks; the innovator’s dilemma; massive open online courses (MOOCs); Creative Commons; the Barack Obama Presidential campaigns; and the Arab Spring. Several major changes in the media environment since the publication of the third edition stand out. Of particular importance has been the rise of social media platforms such as Facebook, Twitter and YouTube, which draw out even more strongly the features of the internet as networked and participatory media, with a range of implications across the economy, society and culture. In addition, the political implications of new media have become more apparent with a range of social media-based political campaigns, from Barack Obama’s successful Presidential election campaigns to the Occupy movements and the Arab Spring. At the same time, the subsequent developments of politics in these and other cases has drawn attention to the limitations of thinking about the politics or the public sphere in technologically determinist ways. When the first edition of New Media was published in 2002, the concept of new media was seen as being largely about the internet as it was accessed from personal computers. The subsequent decade has seen a proliferation of platforms and devices: we now access media in all forms from our phones and other mobile platforms, therefore we seen television and the internet increasingly converging, and we see a growing uncoupling of digital media content and delivery platforms. While this has a range of implications for media law and policy, from convergent media policy to copyright reform, governments and policy-makers are struggling to adapt to such seismic shifts from mass communications media to convergent social media. The internet is no longer primarily a Western-based medium. Two-thirds of the world’s internet users are now outside of Europe and North America; three-quarters of internet users use languages other than English; and three-quarters of the world’s mobile cellular phone subscriptions are in developing nations. It is also apparent that conducting discussions about how to develop new media technologies and discussions about their cultural and creative content can no longer be separated. Discussions of broadband strategies and the knowledge economy need to be increasingly joined with those concerning the creative industries and the creative economy.

Getting a piece of the cloud

Introduction When it comes to sustainable economic development, it is hard to go past the thought of investment in information technology (IT). The foundation of sustainable economic development is sustainable infrastructure. This situation means that investment in IT is about developing sustainable IT infrastructure. An IT infrastructure is a set of IT tools on which organisations could develop applications to manage their varying business processes. At a national economic level, this is all about developing a national IT infrastructure to provide social and economic services to the various stakeholders. Current troubling economic times call for collaboration and centrality in IT infrastructure development. This notion has led to the idea of national broadband networks, sustainable telecommunication platforms, and national IT development plans and goals. However, these thoughts and actions do not directly impact the critical social and economic processes of organisations. That is, these thoughts set the tone and direction of actions

Academics in the policy process : engagement with Australian media policy inquiries 2011-2013

This paper critically evaluates the series of inquires that the Australian Labor government undertook during 2011-2013 into reform of Australian media, communications and copyright laws. One important driver of policy reform was the government’s commitment to building a National Broadband Network (NBN), and the implications this had for existing broadcasting and telecommunications policy, as it would constitute a major driver of convergence of media and communications access devices and content platforms. These inquiries included: the Convergence Review of media and communications legislation; the Australian Law Reform Commission (ALRC) review of the National Classification Scheme; and the Independent Media Inquiry (Finkelstein Review) into Media and Media Regulation. One unusual feature of this review process was the degree to which academics were involved in the process, not simply as providers of expert opinion, but as review chairs seconded from their universities. This paper considers the role played by activist groups in all of these inquiries and their relationship to the various participants in the inquiries, as well as the implications of academics being engaged in such inquiries, not simply as activist-scholars, but as those primarily responsible for delivering policy review outcomes. The paper draws upon the concept of "policy windows" in order to better understand the context in which the inquiries took place, and their relative lack of legislative impact.

At home on the outstation : barriers to home Internet in remote Indigenous communities

Indigenous Australians living in remote areas have little access to the Internet and make little use of it. This article investigates the various dimensions of Internet take-up in remote Indigenous communities in Australia and considers the implications for broadband policy. It focuses specifically on the circumstances and experiences of three remote Indigenous communities in central Australia. Residents in these communities provided significant insight into the social, economic and cultural aspects of communications access and use. This evidence is used to examine the drivers and barriers to home Internet for remote Indigenous communities and to discuss a complex set of issues, including: the dynamics of remote living, economic priorities, cultural engagement with technology, and the characteristics of domestic life in remote Indigenous communities.

The effect of temperature on the mechanism of photoluminescence from plasma-nucleated, nitrogenated carbon nanotips

Nitrogenated carbon nanotips (NCNTPs) have been synthesized using customized plasma-enhanced hot filament chemical vapor deposition. The morphological, structural, and photoluminescent properties of the NCNTPs are investigated using scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and photoluminescence spectroscopy. The photoluminescence measurements show that the NCNTPs predominantly emit a green band at room temperature while strong blue emission is generated at 77 K. It is shown that these very different emission behaviors are related to the change of the optical band-gap and the concentration of the paramagnetic defects of the carbon nanotips. The studies shed light on the controversies on the photoluminescence mechanisms of carbon-based amorphous films measured at different temperatures. The relevance of the results to the use of nitrogenated carbon nanotips in light-emitting optoelectronic devices is discussed.

Room-temperature photoluminescence from nitrogenated carbon nanotips grown by plasma-enhanced hot filament chemical vapor deposition

Nitrogenated carbon nanotips with a low atomic concentration of nitrogen have been synthesized by using a custom-designed plasma-enhanced hot-filament plasma chemical vapor deposition system. The properties (including morphology, structure, composition, photoluminescence, etc.) of the synthesized nitrogenated carbon nanotips are investigated using advanced characterization tools. The room-temperature photoluminescence measurements show that the nitrogenated carbon nanotips can generate two distinct broad emissions located at ∼405 and ∼507 nm, respectively. Through the detailed analysis, it is shown that these two emission bands are attributed to the transition between the lone pair valence and bands, which are related to the sp3 and sp2 C-N bonds, respectively. These results are highly relevant to advanced applications of nitrogenated carbon nanotips in light emitting optoelectronic devices.

Temperature-dependent growth mechanisms of low-dimensional ZnO nanostructures

One-dimensional ZnO nanostructures were successfully synthesized on single-crystal silicon substrates via a simple thermal evaporation and vapour-phase transport method under different process temperatures from 500 to 1000 °C. The detailed and in-depth analysis of the experimental results shows that the growth of ZnO nanostructures at process temperatures of 500, 800, and 1000 °C is governed by different growth mechanisms. At a low process temperature of 500 °C, the ZnO nanostructures feature flat and smooth tips, and their growth is primarily governed by the vapour-solid mechanism. At an intermediate process temperature of 800 °C, the ZnO nanostructures feature cone-shape tips, and their growth is primarily governed by the self-catalyzed and saturated vapour–liquid–solid mechanism. At a high process temperature of 1000 °C, the alloy tip appears on the front side of the ZnO nanostructures, and their growth is primarily governed by the common catalyst-assisted vapour–liquid–solid mechanism. It is also shown that the morphological, structural, optical, and compositional properties of the synthesized ZnO nanostructures are closely related to the process temperature. These results are highly relevant to the development of light-emitting diodes, chemical sensors, energy conversion devices, and other advanced applications.