Channelization for Multi-Standard Software-Defined Radio Base Stations

As the number of radio standards increase and spectrum resources come under more pressure, it becomes ever less efficient to reserve bands of spectrum for exclusive use by a single radio standard. Therefore, this work focuses on channelization structures compatible with spectrum sharing among multiple wireless standards and dynamic spectrum allocation in particular. A channelizer extracts independent communication channels from a wideband signal, and is one of the most computationally expensive components in a communications receiver. This work specifically focuses on non-uniform channelizers suitable for multi-standard Software-Defined Radio (SDR) base stations in general and public mobile radio base stations in particular. A comprehensive evaluation of non-uniform channelizers (existing and developed during the course of this work) shows that parallel and recombined variants of the Generalised Discrete Fourier Transform Modulated Filter Bank (GDFT-FB) represent the best trade-off between computational load and flexibility for dynamic spectrum allocation. Nevertheless, for base station applications (with many channels) very high filter orders may be required, making the channelizers difficult to physically implement. To mitigate this problem, multi-stage filtering techniques are applied to the GDFT-FB. It is shown that these multi-stage designs can significantly reduce the filter orders and number of operations required by the GDFT-FB. An alternative approach, applying frequency response masking techniques to the GDFT-FB prototype filter design, leads to even bigger reductions in the number of coefficients, but computational load is only reduced for oversampled configurations and then not as much as for the multi-stage designs. Both techniques render the implementation of GDFT-FB based non-uniform channelizers more practical. Finally, channelization solutions for some real-world spectrum sharing use cases are developed before some final physical implementation issues are considered

Cognitive Radio Systems

Cognitive radio is a hot research area for future wireless communications in the recent years. In order to increase the spectrum utilization, cognitive radio makes it possible for unlicensed users to access the spectrum unoccupied by licensed users. Cognitive radio let the equipments more intelligent to communicate with each other in a spectrum-aware manner and provide a new approach for the co-existence of multiple wireless systems. The goal of this book is to provide highlights of the current research topics in the field of cognitive radio systems. The book consists of 17 chapters, addressing various problems in cognitive radio systems

High-Performance On-Chip Microwave Photonic Signal Processing Using Linear and Nonlinear Optics

Manipulating and processing radio-frequency (RF) signals using integrated photonic devices has recently emerged as a paradigm-shifting technology for future microwave applications. This emerging technique is referred to as integrated microwave photonics (IMWP) which enables the high-frequency processing and unprecedentedly wideband tunability in compact photonic circuits, with significantly enhanced stability and robustness. However, to find widespread applications, the performance of IMWP devices must meet or exceed the achievable performance of conventional electronic counterparts. The work presented in this thesis investigates high-performance IMWP signal processing from two aspects: the optimized IMWP processing schemes and the photonic integration. Firstly, we explore novel schemes to improve the performance of chip-based microwave photonic subsystems, such as RF delay lines and RF filters which are basic building blocks of RF systems. A phase amplification technique is demonstrated to achieve a Si3N4 chip-based RF time delay with a delay tuning speed at gigahertz level. A new scheme to achieve an all-optimized RF photonic notch filter is demonstrated, producing a record-high RF link performance and complete functionalities. To unlock the potential of RF signal processing, we investigate a new filter concept of pairing linear and nonlinear optics for a high-performance RF photonic filter. To reduce the footprint of the novel IMWP filter, the photonic integration of both the ring resonators and Brillouin-active circuits on the same photonic chip is achieved. To eliminate the use of integrated optical circulators for on-chip SBS, on-chip backward inter-modal stimulated Brillouin scattering is predicted and experimentally demonstrated in a Si-Chalcogenide hybrid integrated photonic platform. The study and demonstrations presented in this thesis make the first viable step towards high-performance IMWP signal processing for real-world RF applications

Impacto do comportamento transitório de sistemas de radiocomunicações na gestão do espectro

Doutoramento em Engenharia EletrotécnicaThis PhD Thesis falls within the domain of spectrum engineering and spectrum management, and intends to address current and concrete problems, with which, regulators have to deal. Particularly, the definition of technical conditions to be met by radio systems, which will operate in specific bands, selected to introduce novel concepts such as flexibility and technological neutrality. The Block Edge Mask approach was adopted to define technical conditions of operation, in those bands. However, this model, based on spectral masks, which are defined in the frequency domain, do not take into account the transient behavior or time-varying characteristics of signals used by emerging radio communication systems. Furthermore, measurement methodologies developed for validation of technical parameters associated to these models, which are recommended by international bodies, potentially lead to practical issues that must be scrutinized. Thus, alternative time-frequency mixed domain signal processing techniques are explored, in this thesis, to be used for assessing the compliance of radio systems operating under such constraints.Esta Tese de Doutoramento insere-se nos domínios da engenharia do espectro e da gestão do espectro radioelétrico, e pretende abordar problemas atuais e concretos com que os reguladores se deparam. Em particular, a definição de condições técnicas a serem cumpridas pelos sistemas rádio que irão operar em determinadas faixas de frequências, selecionadas para a introdução de abordagens de gestão do espectro mais flexíveis e tecnologicamente neutras. O modelo de Máscara Delimitadora de Bloco (Block Edge Mask) foi adotado, a nível europeu, como estratégia de definição de condições técnicas de operação, nessas faixas. Contudo, este modelo, que recorre a restrições que são apenas estabelecidas no domínio da frequência, não entra em linha de conta com comportamentos transitórios ou com a variabilidade temporal de sinais inerentes aos sistemas de radiocomunicações atuais. Para além disso, a medição e validação de parâmetros técnicos associados a estes modelos, conforme definidas nas recomendações internacionais aplicáveis, levantam problemas práticos que importa escalpelizar. Nesse sentido, são exploradas, nesta tese, técnicas alternativas de processamento de sinal no domínio misto tempo-frequência, tendo em vista a sua utilização na avaliação de conformidade dos sistemas rádio em face das restrições aplicáveis

Proceedings of the Third International Mobile Satellite Conference (IMSC 1993)

Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial cellular communications services. While the first and second International Mobile Satellite Conferences (IMSC) mostly concentrated on technical advances, this Third IMSC also focuses on the increasing worldwide commercial activities in Mobile Satellite Services. Because of the large service areas provided by such systems, it is important to consider political and regulatory issues in addition to technical and user requirements issues. Topics covered include: the direct broadcast of audio programming from satellites; spacecraft technology; regulatory and policy considerations; advanced system concepts and analysis; propagation; and user requirements and applications

Advanced Location-Based Technologies and Services

Since the publication of the first edition in 2004, advances in mobile devices, positioning sensors, WiFi fingerprinting, and wireless communications, among others, have paved the way for developing new and advanced location-based services (LBSs). This second edition provides up-to-date information on LBSs, including WiFi fingerprinting, mobile computing, geospatial clouds, geospatial data mining, location privacy, and location-based social networking. It also includes new chapters on application areas such as LBSs for public health, indoor navigation, and advertising. In addition, the chapter on remote sensing has been revised to address advancements