A General Framework for Analyzing, Characterizing, and Implementing Spectrally Modulated, Spectrally Encoded Signals

Fourth generation (4G) communications will support many capabilities while providing universal, high speed access. One potential enabler for these capabilities is software defined radio (SDR). When controlled by cognitive radio (CR) principles, the required waveform diversity is achieved via a synergistic union called CR-based SDR. Research is rapidly progressing in SDR hardware and software venues, but current CR-based SDR research lacks the theoretical foundation and analytic framework to permit efficient implementation. This limitation is addressed here by introducing a general framework for analyzing, characterizing, and implementing spectrally modulated, spectrally encoded (SMSE) signals within CR-based SDR architectures. Given orthogonal frequency division multiplexing (OFDM) is a 4G candidate signal, OFDM-based signals are collectively classified as SMSE since modulation and encoding are spectrally applied. The proposed framework provides analytic commonality and unification of SMSE signals. Applicability is first shown for candidate 4G signals, and resultant analytic expressions agree with published results. Implementability is then demonstrated in multiple coexistence scenarios via modeling and simulation to reinforce practical utility

A 5G Communication system based on flexible spectrum technology for the SKA

Faculty of Science Radio astronomy research is rapidly expanding across the African continent. At the same time, the fifth generation (5G) of mobile communication systems are also being researched and developed. Throughout history, mobile communication networks are known to affect the activities of radio astronomy. If not carefully managed, radio frequencies from mobile communication devices can severely affect radio astronomy observations. To that end, many techniques have been proposed to protect the radio astronomer from RFIs coming from radio communication networks. Some of the proposed techniques such as RFI quite zones and spectrum assignment by regulatory authorities will not be convenient during the implementation of 5G mobile networks. This is because 5G radio communication systems are expected to support spectrum-hungry application such as video-on-demand, augmented realities, high-definition television and so on. To realize this, the 5G networks will be forced to have access to protected radio spectrum, including those at which radio astronomy activities are being researched. To facilitate this, the 5G radio communication networks should have the intelligence to coexist within such protected spectrums without the consequences of radio frequency interferences (RFI) to the primary user. In this thesis, we present novel 5G networks with the intelligence that allow them to coexist within radio astronomy areas without introducing RFIs to the primary user. We proposed a photonic solution, keeping in mind the characteristic requirements for future 5G radio communication networks. The thesis begins by reviewing the current trend of radio astronomy research in Africa. It was found that radio astronomy research in Africa is growing rapidly. Many African countries such as South Africa and Ghana are at advanced stages when it comes to radio astronomy research. Therefore, the finding and proposal of this thesis will be valuable to such countries. In order to develop a radio access network (RAN) that can coexist within radio astronomy areas, the thesis reviewed past and present state-of-the-art RANs. Each access network was analyses for its feasibility to be implemented within radio astronomy areas to realize mobile communication without the consequences of RFIs to the astronomer. It was motivated that the current centralized radio access network (C-RAN) the best solution to be developed for radio communication within radio astronomy areas. This is because the C-RAN architecture is centralized by pooling network resources to a common point. From such pool, network resources can be controlled and shared among 5G network user, including radio astronomers and the surrounding communities. The next chapters reviewed photonic RF transmitters and their associated lasers currently being proposed to be used within C-RANs.Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 202

A 5G Communication system based on flexible spectrum technology for the SKA

Faculty of Science Radio astronomy research is rapidly expanding across the African continent. At the same time, the fifth generation (5G) of mobile communication systems are also being researched and developed. Throughout history, mobile communication networks are known to affect the activities of radio astronomy. If not carefully managed, radio frequencies from mobile communication devices can severely affect radio astronomy observations. To that end, many techniques have been proposed to protect the radio astronomer from RFIs coming from radio communication networks. Some of the proposed techniques such as RFI quite zones and spectrum assignment by regulatory authorities will not be convenient during the implementation of 5G mobile networks. This is because 5G radio communication systems are expected to support spectrum-hungry application such as video-on-demand, augmented realities, high-definition television and so on. To realize this, the 5G networks will be forced to have access to protected radio spectrum, including those at which radio astronomy activities are being researched. To facilitate this, the 5G radio communication networks should have the intelligence to coexist within such protected spectrums without the consequences of radio frequency interferences (RFI) to the primary user. In this thesis, we present novel 5G networks with the intelligence that allow them to coexist within radio astronomy areas without introducing RFIs to the primary user. We proposed a photonic solution, keeping in mind the characteristic requirements for future 5G radio communication networks. The thesis begins by reviewing the current trend of radio astronomy research in Africa. It was found that radio astronomy research in Africa is growing rapidly. Many African countries such as South Africa and Ghana are at advanced stages when it comes to radio astronomy research. Therefore, the finding and proposal of this thesis will be valuable to such countries. In order to develop a radio access network (RAN) that can coexist within radio astronomy areas, the thesis reviewed past and present state-of-the-art RANs. Each access network was analyses for its feasibility to be implemented within radio astronomy areas to realize mobile communication without the consequences of RFIs to the astronomer. It was motivated that the current centralized radio access network (C-RAN) the best solution to be developed for radio communication within radio astronomy areas. This is because the C-RAN architecture is centralized by pooling network resources to a common point. From such pool, network resources can be controlled and shared among 5G network user, including radio astronomers and the surrounding communities. The next chapters reviewed photonic RF transmitters and their associated lasers currently being proposed to be used within C-RANs.Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 202

Design and Implementation of System Components for Radio Frequency Based Asset Tracking Devices to Enhance Location Based Services. Study of angle of arrival techniques, effects of mutual coupling, design of an angle of arrival algorithm, design of a novel miniature reconfigurable antenna optimised for wireless communication systems

The angle of arrival estimation of multiple sources plays a vital role in the field of array signal processing as MIMO systems can be employed at both the transmitter and the receiver end and the system capacity, reliability and throughput can be significantly increased by using array signal processing. Almost all applications require accurate direction of arrival (DOA) estimation to localize the sources of the signals. Another important parameter of localization systems is the array geometry and sensor design which can be application specific and is used to estimate the DOA. In this work, various array geometries and arrival estimation algorithms are studied and then a new scheme for multiple source estimation is proposed and evaluated based on the performance of subspace and non-subspace decomposition methods. The proposed scheme has shown to outperform the conventional Multiple Signal Classification (MUSIC) estimation and Bartlett estimation techniques. The new scheme has a better performance advantage at low and high signal to noise ratio values (SNRs). The research work also studies different array geometries for both single and multiple incident sources and proposes a geometry which is cost effective and efficient for 3, 4, and 5 antenna array elements. This research also considers the shape of the ground plane and its effects on the angle of arrival estimation and in addition it shows how the mutual couplings between the elements effect the overall estimation and how this error can be minimised by using a decoupling matrix. At the end, a novel miniaturised multi element reconfigurable antenna to represent the receiver base station is designed and tested. The antenna radiation patterns in the azimuth angle are almost omni-directional with linear polarisation. The antenna geometry is uniplanar printed logspiral with striplines feeding network and biased components to improve the impedance bandwidth. The antenna provides the benefit of small size, and re-configurability and is very well suited for the asset tracking applications

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High performance, low cost and low consumption Radio-over-Fiber systems for diversified communications applications

This dissertation aims to analyze the possibility of improving in terms of cost and consumption the future Radio-over-Fiber (RoF) systems in different telecommunications scenarios, such as current and next generation of cellular networks and in other applications such as Radio Astronomy. The RoF system studied is hence composed of a Vertical Cavity Surface Emitting Laser (VCSEL) operating at 850 nm, standard single mode fiber (SSMF) and SiGe Heterojunction PhotoTransistor (HPT), adopting the technique called Intensity Modulation-Direct Detection which is nowadays the cheapest and simplest architecture for RoF. This dissertation describes in detail the multimode propagation within the SSMF which is present at 850 nm. Through a developed mathematical model, the two-modes propagation is described and the main phenomena involved are analyzed. The model developed is able to identify the main parameters which contribute to enhance the detrimental effects produced by intermodal dispersion and modal noise both in frequency and time domain. Starting from the model, possible techniques to improve the performances are then proposed. In particular, a pre-filtering technique is realized in order to avoid the excitation of the second order mode, allowing a quasi-single-mode propagation within the SSMF. The technique is theoretically and experimentally validated both for single radio frequency sinusoidal transmission and for bandpass signal. Furthermore, the technique is validated in a LTE transmission system, making the RoF technology proposed able to transmit 256-QAM LTE signal of 20 MHz bandwidth, confirming the possibility to decrease the overall cost and consumption of the network. Further work has been done on the mathematical model. In particular the two modes propagation is exploited in order to characterize the chirp parameter of the VCSEL employed. Finally, the problem of coupling between fiber and opto-electronic devices is also discussed and investigated, in order to improve the efficiency while keeping low the costs

NASA Automated Rendezvous and Capture Review. A compilation of the abstracts

This document presents a compilation of abstracts of papers solicited for presentation at the NASA Automated Rendezvous and Capture Review held in Williamsburg, VA on November 19-21, 1991. Due to limitations on time and other considerations, not all abstracts could be presented during the review. The organizing committee determined however, that all abstracts merited availability to all participants and represented data and information reflecting state-of-the-art of this technology which should be captured in one document for future use and reference. The organizing committee appreciates the interest shown in the review and the response by the authors in submitting these abstracts

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

Components for Wide Bandwidth Signal Processing in Radio Astronomy

In radio astronomy wider observing bandwidths are constantly desired for the reasons of improved sensitivity and velocity coverage. As observing frequencies move steadily higher these needs become even more pressing. In order to process wider bandwidths, components that can perform at higher frequencies are required. The chief limiting component in the area of digital spectrometers and correlators is the digitiser. This is the component that samples and quantises the bandwidth of interest for further digital processing, and must function at a sample rate of at least twice the operating bandwidth. In this work a range of high speed digitiser integrated circuits (IC) are designed using an advanced InP HBT semiconductor process and their performance limits analysed. These digitiser ICs are shown to operate at up to 10 giga-samples/s, significantly faster than existing digitisers, and a complete digitiser system incorporating one of these is designed and tested that operates at up to 4 giga-samples/s, giving 2 GHz bandwidth coverage. The digitisers presented include a novel photonic I/O digitiser which contains an integrated photonic interface and is the first digitiser device reported with integrated photonic connectivity. In the complementary area of analogue correlators the limiting component is the device which performs the multiplication operation inherent in the correlation process. A 15 GHz analogue multiplier suitable for such systems is designed and tested and a full noise analysis of multipliers in analogue correlators presented. A further multiplier design in SiGe HBT technology is also presented which offers benefits in the area of low frequency noise. In the effort to process even wider bandwidths, applications of photonics to digitisers and multipliers are investigated. A new architecture for a wide bandwidth photonic multiplier is presented and its noise properties analysed, and the use of photonics to increase the sample rate of digitisers examined

Space station systems: A bibliography with indexes (supplement 3)

This bibliography lists 780 reports, articles and other documents introduced into the NASA scientific and technical information system between January 1, 1986 and June 30, 1986. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite system. The coverage includes documents that define major systems and subsystems, servicing and support requirements, procedures and operations, and missions for the current and future space station