297 research outputs found
The outlook on white space utilization policy in Korea: Lessons from the DTV leading countries, namely, the US, the UK, and Japan
Some countries have already finished or are progressing toward a transition to Digital Television (DTV). In particular, the US and UK have conducted technical analyses of white space, and its management strategy is under review. They are also working on determining what kind of service could be used for white space. According to this trend, a special research team led by the Japanese government was formed to study DTV white spaces utilization, and its study was conducted at the end of July 2010 [1]. In Korea, a study was recently begun on Cognitive Radio (CR) that could be applied for white spaces. However, no official research is being conducted to quantify the available spaces and their management strategy depending on the service applications. In this paper, we propose an appropriate spectrum management scheme for white space in Korea considering the results of a survey, Spectrum Requirement According to DTV Transition, and an iconography review based on tentatively assigned DTV channels around three DTV pilot test areas, Uljin, Danyang, and Gangjin. --White space,DTV transition,Spectrum policy,Spectrum demand survey,Iconography review,Spectrum management
The Case for Liberal Spectrum Licenses: A Technical and Economic Perspective
The traditional system of radio spectrum allocation has inefficiently restricted wireless services. Alternatively, liberal licenses ceding de facto spectrum ownership rights yield incentives for operators to maximize airwave value. These authorizations have been widely used for mobile services in the U.S. and internationally, leading to the development of highly productive services and waves of innovation in technology, applications and business models. Serious challenges to the efficacy of such a spectrum regime have arisen, however. Seeing the widespread adoption of such devices as cordless phones and wi-fi radios using bands set aside for unlicensed use, some scholars and policy makers posit that spectrum sharing technologies have become cheap and easy to deploy, mitigating airwave scarcity and, therefore, the utility of exclusive rights. This paper evaluates such claims technically and economically. We demonstrate that spectrum scarcity is alive and well. Costly conflicts over airwave use not only continue, but have intensified with scientific advances that dramatically improve the functionality of wireless devices and so increase demand for spectrum access. Exclusive ownership rights help direct spectrum inputs to where they deliver the highest social gains, making exclusive property rules relatively more socially valuable. Liberal licenses efficiently accommodate rival business models (including those commonly associated with unlicensed spectrum allocations) while mitigating the constraints levied on spectrum use by regulators imposing restrictions in traditional licenses or via use rules and technology standards in unlicensed spectrum allocations.
Spectrum Policy and Management
This project provides an examination of the FCC’s policies towards spectrum reallocation. The project examines the National Broadband Plan and how the FCC has approached the goals described within it. The demand for broadband communications has increased dramatically in recent years and has resulted in a predicted spectrum deficit in the near future. In addition to a number of spectrum auctions and their winners the project examines how the redistribution of spectrum impacts the broadband community. The project also provides an examination of spectrum reallocation and policy in other countries, to provide a broader view of spectrum policy. Finally the project examines new spectrum technologies and spectrum usage policies to further examine how the US’s spectrum policies should evolve
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Semi-automated mobile television interactive application generation based on XHTML and Java ME
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 11/02/2011.Mobile Digital TV (MDTV), the hybrid of Digital Television (DTV) and mobile devices (such as mobile phones), has introduced a new way for people to watch DTV and has brought new opportunities for development in the DTV industry. Nowadays, the development of the next generation MDTV service has progressed in terms of both hardware layers and software, with interactive services/applications becoming one of the future MDTV service trends. However, current MDTV interactive services still lack in terms of attracting the consumers and the service creation and implementation process relies too much on commercial solutions, resulting in most parts of the process being proprietary. In addition, this has increased the technical demands for developers as well as has increased substantially the cost of producing and maintaining MDTV services. In light of the aforementioned situation, the Thesis has contributed to this field, by proposing an innovative MDTV service creation and consumption system based on XHTML and Java ME. On the head-end it introduces a semi-automatic creation mechanism to facilitate a less technical and more efficient interactive service creation process. This enables designers and creative individuals to be actively involved in the MDTV service creation process and to develop interactive-rich MDTV service. On the client-end it employs an open-source software environment as the interactive service MDTV consumption platform, rendering the MDTV service implementation process as less proprietary as possible. Furthermore, the Thesis offers a discussion on the different MDTV interactive application models currently used and based on the proposed software, a novel MDTV service presentation method is further introduced and adopted instead of the Rich Media and ECMAScript based methods. Finally, a series of qualitative testing procedures have been implemented with regards to conducting an essential evaluation on the operability of the proposed software system
Ambient RF energy harvesting and efficient DC-load inductive power transfer
This thesis analyses in detail the technology required for wireless power transfer via radio frequency (RF) ambient energy harvesting and an inductive power transfer system (IPT). Radio frequency harvesting circuits have been demonstrated for more than fifty years, but only a few have been able to harvest energy from freely available ambient (i.e. non-dedicated) RF sources. To explore the potential for ambient RF energy harvesting, a city-wide RF spectral survey was undertaken in London. Using the results from this survey, various harvesters were designed to cover four frequency bands from the largest RF contributors within the ultra-high frequency (0.3 to 3 GHz) part of the frequency spectrum. Prototypes were designed, fabricated and tested for each band and proved that approximately half of the London Underground stations were found to be suitable locations for harvesting ambient RF energy using
the prototypes.
Inductive Power Transfer systems for transmitting tens to hundreds of watts have been reported for almost a decade. Most of the work has concentrated on the optimization of the link efficiency and have not taken into account the efficiency of the driver and rectifier. Class-E amplifiers and rectifiers have been identified as ideal drivers for IPT applications, but their power handling capability at tens of MHz has been a crucial limiting factor, since the load and inductor characteristics are set by
the requirements of the resonant inductive system. The frequency limitation of the driver restricts the unloaded Q-factor of the coils and thus the link efficiency. The system presented in this work alleviates the use of heavy and expensive field-shaping techniques by presenting an efficient IPT system capable of transmitting energy with high dc-to-load efficiencies at 6 MHz across a distance of 30 cm.Open Acces
Modelling, Dimensioning and Optimization of 5G Communication Networks, Resources and Services
This reprint aims to collect state-of-the-art research contributions that address challenges in the emerging 5G networks design, dimensioning and optimization. Designing, dimensioning and optimization of communication networks resources and services have been an inseparable part of telecom network development. The latter must convey a large volume of traffic, providing service to traffic streams with highly differentiated requirements in terms of bit-rate and service time, required quality of service and quality of experience parameters. Such a communication infrastructure presents many important challenges, such as the study of necessary multi-layer cooperation, new protocols, performance evaluation of different network parts, low layer network design, network management and security issues, and new technologies in general, which will be discussed in this book
Semi-automated mobile television interactive application generation based on XHTML and Java ME
Mobile Digital TV (MDTV), the hybrid of Digital Television (DTV) and mobile devices (such as mobile phones), has introduced a new way for people to watch DTV and has brought new opportunities for development in the DTV industry. Nowadays, the development of the next generation MDTV service has progressed in terms of both hardware layers and software, with interactive services/applications becoming one of the future MDTV service trends. However, current MDTV interactive services still lack in terms of attracting the consumers and the service creation and implementation process relies too much on commercial solutions, resulting in most parts of the process being proprietary. In addition, this has increased the technical demands for developers as well as has increased substantially the cost of producing and maintaining MDTV services. In light of the aforementioned situation, the Thesis has contributed to this field, by proposing an innovative MDTV service creation and consumption system based on XHTML and Java ME. On the head-end it introduces a semi-automatic creation mechanism to facilitate a less technical and more efficient interactive service creation process. This enables designers and creative individuals to be actively involved in the MDTV service creation process and to develop interactive-rich MDTV service. On the client-end it employs an open-source software environment as the interactive service MDTV consumption platform, rendering the MDTV service implementation process as less proprietary as possible. Furthermore, the Thesis offers a discussion on the different MDTV interactive application models currently used and based on the proposed software, a novel MDTV service presentation method is further introduced and adopted instead of the Rich Media and ECMAScript based methods. Finally, a series of qualitative testing procedures have been implemented with regards to conducting an essential evaluation on the operability of the proposed software system.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Semi-automated mobile television interactive application generation based on XHTML and Java ME
Mobile Digital TV (MDTV), the hybrid of Digital Television (DTV) and mobile devices (such as mobile phones), has introduced a new way for people to watch DTV and has brought new opportunities for development in the DTV industry. Nowadays, the development of the next generation MDTV service has progressed in terms of both hardware layers and software, with interactive services/applications becoming one of the future MDTV service trends. However, current MDTV interactive services still lack in terms of attracting the consumers and the service creation and implementation process relies too much on commercial solutions, resulting in most parts of the process being proprietary. In addition, this has increased the technical demands for developers as well as has increased substantially the cost of producing and maintaining MDTV services. In light of the aforementioned situation, the Thesis has contributed to this field, by proposing an innovative MDTV service creation and consumption system based on XHTML and Java ME. On the head-end it introduces a semi-automatic creation mechanism to facilitate a less technical and more efficient interactive service creation process. This enables designers and creative individuals to be actively involved in the MDTV service creation process and to develop interactive-rich MDTV service. On the client-end it employs an open-source software environment as the interactive service MDTV consumption platform, rendering the MDTV service implementation process as less proprietary as possible. Furthermore, the Thesis offers a discussion on the different MDTV interactive application models currently used and based on the proposed software, a novel MDTV service presentation method is further introduced and adopted instead of the Rich Media and ECMAScript based methods. Finally, a series of qualitative testing procedures have been implemented with regards to conducting an essential evaluation on the operability of the proposed software system.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Solutions for New Terrestrial Broadcasting Systems Offering Simultaneously Stationary and Mobile Services
221 p.[EN]Since the first broadcasted TV signal was transmitted in the early decades of
the past century, the television broadcasting industry has experienced a series of
dramatic changes. Most recently, following the evolution from analogue to digital
systems, the digital dividend has become one of the main concerns of the
broadcasting industry. In fact, there are many international spectrum authorities
reclaiming part of the broadcasting spectrum to satisfy the growing demand of
other services, such as broadband wireless services, arguing that the TV services
are not very spectrum-efficient.
Apart from that, it must be taken into account that, even if up to now the
mobile broadcasting has not been considered a major requirement, this will
probably change in the near future. In fact, it is expected that the global mobile
data traffic will increase 11-fold between 2014 and 2018, and what is more, over
two thirds of the data traffic will be video stream by the end of that period.
Therefore, the capability to receive HD services anywhere with a mobile device is
going to be a mandatory requirement for any new generation broadcasting system.
The main objective of this work is to present several technical solutions that
answer to these challenges. In particular, the main questions to be solved are the
spectrum efficiency issue and the increasing user expectations of receiving high
quality mobile services. In other words, the main objective is to provide technical
solutions for an efficient and flexible usage of the terrestrial broadcasting spectrum
for both stationary and mobile services.
The first contributions of this scientific work are closely related to the study of
the mobile broadcast reception. Firstly, a comprehensive mathematical analysis of
the OFDM signal behaviour over time-varying channels is presented. In order to
maximize the channel capacity in mobile environments, channel estimation and
equalization are studied in depth. First, the most implemented equalization
solutions in time-varying scenarios are analyzed, and then, based on these existing
techniques, a new equalization algorithm is proposed for enhancing the receivers’
performance.
An alternative solution for improving the efficiency under mobile channel
conditions is treating the Inter Carrier Interference as another noise source.
Specifically, after analyzing the ICI impact and the existing solutions for reducing
the ICI penalty, a new approach based on the robustness of FEC codes is
presented. This new approach employs one dimensional algorithms at the receiver
and entrusts the ICI removing task to the robust forward error correction codes.
Finally, another major contribution of this work is the presentation of the
Layer Division Multiplexing (LDM) as a spectrum-efficient and flexible solution
for offering stationary and mobile services simultaneously. The comprehensive
theoretical study developed here verifies the improved spectrum efficiency,
whereas the included practical validation confirms the feasibility of the system and
presents it as a very promising multiplexing technique, which will surely be a strong
candidate for the next generation broadcasting services.[ES]Desde el comienzo de la transmisión de las primeras señales de televisión a
principios del siglo pasado, la radiodifusión digital ha evolucionado gracias a una
serie de cambios relevantes. Recientemente, como consecuencia directa de la
digitalización del servicio, el dividendo digital se ha convertido en uno de los
caballos de batalla de la industria de la radiodifusión. De hecho, no son pocos los
consorcios internacionales que abogan por asignar parte del espectro de
radiodifusión a otros servicios como, por ejemplo, la telefonía móvil, argumentado
la poca eficiencia espectral de la tecnología de radiodifusión actual.
Asimismo, se debe tener en cuenta que a pesar de que los servicios móviles no
se han considerado fundamentales en el pasado, esta tendencia probablemente
variará en el futuro cercano. De hecho, se espera que el tráfico derivado de
servicios móviles se multiplique por once entre los años 2014 y 2018; y lo que es
más importante, se pronostica que dos tercios del tráfico móvil sea video streaming
para finales de ese periodo. Por lo tanto, la posibilidad de ofrecer servicios de alta
definición en dispositivos móviles es un requisito fundamental para los sistemas de
radiodifusión de nueva generación.
El principal objetivo de este trabajo es presentar soluciones técnicas que den
respuesta a los retos planteados anteriormente. En particular, las principales
cuestiones a resolver son la ineficiencia espectral y el incremento de usuarios que
demandan mayor calidad en los contenidos para dispositivos móviles. En pocas
palabras, el principal objetivo de este trabajo se basa en ofrecer una solución más
eficiente y flexible para la transmisión simultánea de servicios fijos y móviles.
La primera contribución relevante de este trabajo está relacionada con la
recepción de la señal de televisión en movimiento. En primer lugar, se presenta un
completo análisis matemático del comportamiento de la señal OFDM en canales
variantes con el tiempo. A continuación, con la intención de maximizar la
capacidad del canal, se estudian en profundidad los algoritmos de estimación y
ecualización. Posteriormente, se analizan los algoritmos de ecualización más
implementados, y por último, basándose en estas técnicas, se propone un nuevo
algoritmo de ecualización para aumentar el rendimiento de los receptores en tales
condiciones.
Del mismo modo, se plantea un nuevo enfoque para mejorar la eficiencia de
los servicios móviles basado en tratar la interferencia entre portadoras como una
fuente de ruido. Concretamente, tras analizar el impacto del ICI en los receptores
actuales, se sugiere delegar el trabajo de corrección de dichas distorsiones en
códigos FEC muy robustos.
Finalmente, la última contribución importante de este trabajo es la
presentación de la tecnología LDM como una manera más eficiente y flexible para
la transmisión simultánea de servicios fijos y móviles. El análisis teórico presentado
confirma el incremento en la eficiencia espectral, mientras que el estudio práctico
valida la posible implementación del sistema y presenta la tecnología LDM c
Cognitive-radio systems for spectrum, location, and environmental awareness
In order to perform reliable communications, a system needs to have sufficient information about its operational environment, such as spectral resources and propagation characteristics. Cognitive-radio technology has capabilities for acquiring accurate spectrum, location, and environmental information, due to its unique features such as spectrum, location, and environmental awareness. The goal of this paper is to give a comprehensive review of the implementation of these concepts. In addition, the dynamic nature of cognitive-radio systems - including dynamic spectrum utilization, transmission, the propagation channel, and reception - is discussed, along with performance limits, challenges, mitigation techniques, and open issues. The capabilities of cognitive-radio systems for accurate characterization of operational environments are emphasized. These are crucial for efficient communications, localization, and radar systems. © 2010 IEEE
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