The UHF band between 470-790 MHz, currently occupied by digital ter- restrial TV (DTT) distribution in Europe, is widely regarded as a premium spectrum band for providing mobile coverage. With the exponential increase in wireless data traffic in recent years, there has been growing interests in gaining access to this spectrum band for wireless broadband services. The secondary access in TV White Space is considered as one cost-effective way to reuse the spectrum unoccupied by the primary DTT network. On the other hand, the declining influence of DTT and the converging trends of video con- sumption on TV and mobile platforms are new incentives for the regulator to reconsider the optimal utilization of the UHF broadcast band. The proposal to re-farm the UHF band for a converged content distribution network was born under theses circumstances. This thesis intends to develop a methodology for evaluating the technical performance of these options for utilizing UHF broadcast band and quantify- ing their gains in terms of achievable extra capacity and spectrum savings. For the secondary access in TV white space, our study indicates a considerable po- tential for low power secondary, which is mostly limited by the adjacent chan- nel interference generated from the densely deployed secondary devices due to the cumulative effect of multichannel interference. On the other hand, this potential does not translate directly into capacity for a WiFi-like secondary system based on CSMA/CA protocol, as the network congestion and self- interference within the secondary system has a greater impact on the network throughput than the primary interference constraint. Our study on the cellular content distribution network reveals more po- tential benefits for re-farming the UHF broadcast band and reallocating it for a converged platform. This platform is based on cellular infrastructure and can provide TV service with the same level of quality requirement as DTT by delivering the video content via either broadcast or unicast as the situa- tion dictates. We have developed a resource manage framework to minimize its spectrum requirement for providing TV service and identified a significant amount of spectrum that can be reused by the converged platform to provide extra mobile broadband capacity in urban and sparsely populated rural areas. Overall, we have arrived at the conclusion that the concept of cellular con- tent distribution in a re-farmed UHF band shows a more promising prospect than the secondary access in TV white space in the long run. Nevertheless, low power secondary is still considered as a flexible and low-cost way to exploit the underutilized spectrum in the short term, despite its uncertainty in future availability. On the other hand, the re-farming of UHF broadcast band is a long and difficult regulation process with substantial opposition from the in- cumbent.The results from this study could serve as input for future regulatory decisions on the UHF band allocation and cost-benefit analysis for deploying new systems to access this spectrum band. / <p>QC 20140609</p> / EU FP7 QUASAR / EU FP7 METIS

Les techniques à base d’antennes multiples constituent une solution intéressante à l’augmentation du débit sans accroître la bande passante. Cependant, la conception de systèmes à base de diversité soulève de nouveaux défis quant à leur intégration au sein de terminaux à encombrement réduit. Le travail présenté consiste à prendre en compte conjointement les éléments déterminant les performances de communication multi-antennes et les contraintes d’intégration liées aux terminaux. Les systèmes développés fonctionnent dans deux bandes LTE: 790-862 MHz et 2.5-2.69 GHz; certains couvrent également la partie haute de la bande TVWS (TV White Space): 700-790 MHz afin d’offrir des applications de radio cognitive. Pour la première conception, la démarche consiste à obtenir un système performant sans rechercher, dans un premier temps une forte intégration. Néanmoins, le système proposé est intégrable dans des terminaux émergeant dans le marché actuel comme l’hybride téléphone-tablette. Des performances très satisfaisantes en termes de bandes et d’isolation sont atteintes. Ensuite, on privilégie la compacité du système tout en offrant des performances acceptables. Cette démarche permet la conception de trois prototypes, dont le dernier est intégrable dans un téléphone.D’autre part, l’influence de la présence d’un utilisateur mais également de l’intégration dans un terminal multimédia sur les performances des systèmes est étudiée. Enfin, les performances en diversité sont évaluées dans différentes configurations d’environnements. Les résultats ont montré que ces systèmes sont adaptés à la technologie LTE et offrent la possibilité d’établir des communications sans fil MIMO. / Multiple antennas techniques are an interesting solution to increase throughput without increasing the bandwidth. This is an advantage in a context where the proliferation of users and services leads to a saturation of spectrum. However, the systems based on diversity raise new challenges for their integration into terminals. The work presented in this thesis is to consider jointly the performance of multi-antennas systems and integration into terminals constraints. Developed systems operate in two bands LTE: 790-862 MHz and 2.5-2.69 GHz, and cover also for some of them the upper part of the band TVWS (TVWhite Space): 700-790 MHz to provide cognitive radio applications. The first study is concentrated on designing an efficient system while maintaining a reasonable size. The proposed system is integrated into the terminals emerging in the market today such as mini-tablets, the tablet-phone hybrid or laptop. Very satisfactory performance in terms of bands and isolation are achieved. Aiming the size reduction, we propose an alternative compact system providing acceptable performances. For this purpose, three prototypes are proposed where the last could be integrated into a mobile phone. For all systems, we have evaluated the diversity performances in terms of correlation coefficient and Mean Effective Gain. It has been founded that the systems provide good diversity performances even if the terminal's position is changed during the communication. Moreover, the influence on the antennas performances with a presence of users is studied. The results show that these systems are suitable for LTE and can be used for MIMO wireless communications.

The TV white space (TVWS) is one of the promising technologies to provide wide coverage, energy effcient and cost effective Internet of Things (IoT) services. However, its low operating frequency and wide bandwidth poses significant challenges to antenna designs. In this thesis, three antennas are developed using the characteristic mode analysis (CMA) for IoT devices operating over the TVWS. First, a very-low profile circular small antenna is transformed from a vertical monopole antenna. The CMA is used to determine the mode to be excited and to design a specific feeding structure. After being printed on Rogers 5880 substrate, the final antenna structure operates at 474 MHz with a V SWR < 2 bandwidth of 2.2 MHz. Its lateral radius is just 5.2% of the wavelength of its resonant frequency. Second, a compact U-shaped printed UWB monopole antenna is proposed to operate over the entire UHF TV spectrum. This antenna measures 0:36 0 0:06 0 0:01 0 where 0 is the wavelength of its lowest operating frequency. Its V SWR < 2 bandwidth is 87.5%, and the UWB behaviour is discussed by the CMA. Third, a novel antenna design method is established on annular ring-shaped structures with modal characteristics revealed by the CMA. Following the proposed method, another UWB antenna is achieved by creating and exciting multiple modes with resonant frequencies distributed across the UHF TV spectrum. All antenna designs are verified thorough simulations and measurements. Furthermore, antennas are also integrated into IoT devices and their system performance is measured under different communication scenarios. The system measurements also verify the good propagation property and the abundant spectrum resource of the TVWS.

The sharing of the terrestrial TV frequency spectrum with Secondary Users (SUs) is presently the focus point of numerous research efforts worldwide. In many regulatory domains, contiguous blocks of VHF and UHF spectrum are available for exclusive use by the terrestrial TV broadcasting incumbents. However, this notion is currently challenged by the spectrum management paradigm of Dynamic Spectrum Access (DSA), advocating that this spectrum may be shared on a dynamic basis with SUs. The migration of analogue terrestrial TV to Digital Terrestrial Television (DTT) has also catalysed the notion that the terrestrial TV frequency spectrum will no longer be exclusively used for terrestrial broadcasting. Some administrations have already embraced this technology, reforming spectrum policy to allow unlicensed secondary access to the Spectral Opportunities (SOs) present in the terrestrial TV frequency bands. The Independent Communications Authority of South Africa (ICASA) has expressed early interest in the possibilities of TV white space technology and its possible utility in exploiting the SOs that exist in the terrestrial TV frequency bands. Core to the issues mentioned above is the quantification of the Spectral Opportunity (SO) available. To this end, the work presented in this thesis gives a quantified estimate of the SO available in South Africa. This work is the first of its kind for the South African environment and uncovers new knowledge regarding SO in South Africa. SO is analysed and quantified on provincial and national level for three discrete points in time: before the start of dual-illumination, during dual illumination and after analogue switch-off. A system model that is able to produce the required geo-referenced field strength coverage and SO maps is conceptualised and implemented. A complete standards compliant model is implemented from scratch, verified and validated, with design decisions specific to the South African context. The analysis methodology is developed with rigour. The construction of the TV transmitter database, definition of incumbent protection criteria and development of the required analysis metrics to quantify SO are presented. SO in the VHF and UHF terrestrial TV frequency bands is quantified by expressing SO in terms of the number of available channels, weighted respectively by land area and population density. The analysis results indicate that significant SO is available for exploitation by TV white space devices in the terrestrial TV spectrum in South Africa. The effects of radio astronomy advantage areas on the SO available are also investigated. The probability of finding contiguous channels in the Very High Frequency (VHF) and Ultra High Frequency (UHF) bands is also quantified. A comparative study, comparing the SO for South Africa with related work in Europe and the United States of America (USA), is also performed. Finally, maps that visualise the SO available are constructed for the three discrete time periods evaluated. / Thesis (PhD (Computer Engineering))--North-West University, Potchefstroom Campus, 2013

The sharing of the terrestrial TV frequency spectrum with Secondary Users (SUs) is presently the focus point of numerous research efforts worldwide. In many regulatory domains, contiguous blocks of VHF and UHF spectrum are available for exclusive use by the terrestrial TV broadcasting incumbents. However, this notion is currently challenged by the spectrum management paradigm of Dynamic Spectrum Access (DSA), advocating that this spectrum may be shared on a dynamic basis with SUs. The migration of analogue terrestrial TV to Digital Terrestrial Television (DTT) has also catalysed the notion that the terrestrial TV frequency spectrum will no longer be exclusively used for terrestrial broadcasting. Some administrations have already embraced this technology, reforming spectrum policy to allow unlicensed secondary access to the Spectral Opportunities (SOs) present in the terrestrial TV frequency bands. The Independent Communications Authority of South Africa (ICASA) has expressed early interest in the possibilities of TV white space technology and its possible utility in exploiting the SOs that exist in the terrestrial TV frequency bands. Core to the issues mentioned above is the quantification of the Spectral Opportunity (SO) available. To this end, the work presented in this thesis gives a quantified estimate of the SO available in South Africa. This work is the first of its kind for the South African environment and uncovers new knowledge regarding SO in South Africa. SO is analysed and quantified on provincial and national level for three discrete points in time: before the start of dual-illumination, during dual illumination and after analogue switch-off. A system model that is able to produce the required geo-referenced field strength coverage and SO maps is conceptualised and implemented. A complete standards compliant model is implemented from scratch, verified and validated, with design decisions specific to the South African context. The analysis methodology is developed with rigour. The construction of the TV transmitter database, definition of incumbent protection criteria and development of the required analysis metrics to quantify SO are presented. SO in the VHF and UHF terrestrial TV frequency bands is quantified by expressing SO in terms of the number of available channels, weighted respectively by land area and population density. The analysis results indicate that significant SO is available for exploitation by TV white space devices in the terrestrial TV spectrum in South Africa. The effects of radio astronomy advantage areas on the SO available are also investigated. The probability of finding contiguous channels in the Very High Frequency (VHF) and Ultra High Frequency (UHF) bands is also quantified. A comparative study, comparing the SO for South Africa with related work in Europe and the United States of America (USA), is also performed. Finally, maps that visualise the SO available are constructed for the three discrete time periods evaluated. / Thesis (PhD (Computer Engineering))--North-West University, Potchefstroom Campus, 2013

The aim of this thesis is to analyze how technological, economic, political and social factors can be integrated into Business Model for Geo-location database as a controlling entity for operation of Cognitive Radio devices in the TV White Space spectrum range. Tasks of thesis: to perform an analysis of scientific literature in the context of TVWS and to identify technologies of TVWS management, to find factors influencing Geo-location Database Business Model, to put forward Geo-location Database scenarios, to construct classification of Business Model for the Geo-location Database, to provide experimental study of feasibility to deploy distinct classification of Business Model for the distinct scenarios of Geo-location Database. Qualitative methods chosen for the research: exploratory literature analysis, consultations with experts/specialists and conceptual modelling based on scenarios. The exploratory part of the thesis describes existing spectrum shortage problem and presents potential technologies that can solve this problem. The theoretical part of this work introduces research methodology and the concept and principles of Business Model for technology innovation. Analytical part of the thesis seeks to identify potential Business Model configurations for the operations of Geo-location database in the TV White Space spectrum range. This part ends with presenting experimental study of the feasibility of Geo-location Business Model. The final part of the thesis concludes... [to full text] / Šio darbo tikslas – išanalizuoti, kaip technologiniai, ekonominiai, politiniai ir socialiniai faktoriai gali būti integruoti į verslo modelį, skirtą TV spektro tuštumų geografinei duomenų bazei, naudojančiai sumaniojo radijo ryšio sistemas. Tikslui pasiekti išsikelti uždaviniai: atlikti mokslinės literatūros analizę TV spektro tuštumų tema ir identifikuoti spektro tuštumų valdymo technologijas, nustatyti veiksnius, įtakojančius geografinės duomenų bazės verslo modelį, sudaryti geografinės duomenų bazės verslo scenarijus, sudaryti geografinės duomenų bazės verslo modelių klasifikaciją, nustatyti sudarytos verslo modelių klasifikacijos tinkamumą kiekvienam scenarijui bei nustatyti optimalią verslo modelio konfigūraciją. Uždaviniams įgyvendinti taikyti kokybiniai metodai: mokslinės literatūros analizė, konsultacijos su ekspertais bei specialistais, konceptualus modeliavimas, paremtas scenarijų metodu. Pirmoje darbo dalyje aprašomos egzistuojančios spektro trūkumo problemos ir apžvelgiamos potencialios technologijos, kurios gali išspręsti išanalizuotą problemą. Antroji darbo dalis pristato tyrimo metodus ir nagrinėja verslo modelį bei jo principus, galinčius įtakoti technologijos inovaciją. Trečioji darbo dalis siekia identifikuoti ir įvertinti potencialius TV spektro tuštumų geografinės duomenų bazės verslo modelius. Pateikiamos darbo išvados atsižvelgiant į darbo naudingumą, praktiškumą ir esamus apribojimus. Pagrindiniai darbo rezultatai: nustatyta optimali verslo modelių... [toliau žr. visą tekstą]