Time-Reversal Routing for Dispersion Code Multiple Access (DCMA) Communications

We present the modeling and characterization of a time-reversal routing dispersion code multiple access (TR-DCMA) system. We show that this system maintains the low complexity advantage of DCMA transceivers while offering dynamic adaptivity for practial communication scenarios. We first derive the mathematical model and explain operation principles of the system, and then characterize its interference, signal to interference ratio, and bit error probability characteristics

Time-reversal routing for dispersion code multiple access (DCMA) communications

ABSTRACT: We present the modeling and characterization of a time-reversal routing dispersion code multiple access (TR-DCMA) system. We show that this system maintains the low complexity advantage of DCMA transceivers while offering dynamic adaptivity for practical communication scenarios. We first derive the mathematical model and explain operation principles of the system, and then characterize its interference, signal to interference ratio and bit error probability characteristics

Dispersion Based Real-Time Analog Signal Processing (R-ASP) and Application to Wireless Communications

RÉSUMÉ Nous sommes confrontés à une demande explosive de systèmes radio plus rapides, plus fiables et plus écoénergétiques, pour la communication sans fil 5G par exemple. On s’attend à ce que la capacité des données mobiles dépasse 1000 fois ce qu’elle est actuellement dans la prochaine décennie. Un tel volume de données nécessite un grand spectre de bande passante. Aux fréquences radio-fréquences (RF) faibles, le spectre est congestionné par des milliards d’appareils radio. Dans les hautes fréquences, le spectre de bande passante ultra large (UWB) est moins congestionné. Cependant, le traitement d’un tel signal UWB RF pose de grands défis au niveau du traitement du signal (DSP) numérique, qui est habituellement utilisé pour les basses fréquences et les bandes passantes étroites. Les problèmes dont souffre le DSP pour les signaux hautes fréquences sont la limitation de la vitesse, le coût élevé et la forte consommation d’énergie pour la conversion analogique / numérique (ADC). Par conséquent, une technique de traitement en temps réel et purement analogique est souhaitable. En optique, les gens ont traité des signaux RF UWB avec des approches photoniques hyperfréquences en temps réel, mais cela impliquait une conversion électrique / optique coûteuse. Le traitement de signal analogique d’une onde radio en temps réel (R-ASP) est une alternative attrayante et moins exploitée. Le premier chapitre présente l’état de l’art de la technologie R-ASP ainsi que la contribution de la thèse. Le composant au coeur du traitement R-ASP s’appelle "phaseur", un composant qui fournit un retard de groupe spécifié � (!) à une onde radio. Un phaseur, en réponse à un signal d’excitation large bande, réorganise les composants spectraux dans le temps. La façon dont un phaseur réorganise le spectre dépend de la fonction de retard de groupe, � (!). Différentes applications R-ASP peuvent nécessiter des profils de retard de groupe différents. Le chapitre 2 introduit le concept de retard de groupe, présente différentes technologies phaseur, et présente une méthode pour augmenter la quantité de délai de groupe en utilisant des phaseurs réfléchissants passifs. Un phaseur passif et passe-tout (qui ne filtre aucune fréquence) affiche une perte qui est proportionnelle au retard de groupe, ce qui entraîne une distorsion du signal. Le chapitre trois présente une solution à ce problème, qui consiste en une mise en cascade d’un phaseur ayant du gain et un phaseur ayant des pertes.---------- ABSTRACT We are facing exploding demands for faster, more reliable, more energy-efficient radio systems, such as for instance 5G wireless communication. It is expected that for the next decade the mobile data capacity would exceed 1000 times higher than it is right now. Such high data volume requires large bandwidth spectrum resources. In low RF frequencies, the precious spectrum have been congested by zillions of radio devices. In high frequencies, such as millimeter wave, ultra wideband (UWB) spectrum is much easier available. However, processing UWB RF signal poses great difficulties on conventional digital signal processing (DSP) technique that has prevailed for low frequency and small bandwidth processing. For instance, DSP suffers limited speed, high cost and high power consumption for analog/digital conversion (ADC). Therefore, real-time and purely analog processing technique is desirable. In optics, people have been processing UWB RF signal with microwave photonics approaches, which is real-time, but involves expensive and lossy electrical/optical conversion. The direct radio Real-time Analog Signal Processing (R-ASP) is thus tractive but less exploited. Chapter 1 presents the advancements of R-ASP along with the contributions of the thesis. The core of R-ASP is “phaser”, which is a group delay engineered component that provides specified group delay function � (!). A phaser, in response to a wideband signal excitation, rearranges spectral components in time. The way a phaser arranges spectral components is controlled by the group delay function, � (!). Different R-ASP applications may require different group delay profiles. Chapter 2 introduces the concept of group delay engineering, different phaser technologies, and presents an R-ASP resolution (group delay swing) enhancement example using passive reflective phaser units. Passive phaser exhibits loss that is proportional to the group delay, i.e. imbalance amplitude, which typically results in undesired processing distortion. It is found that a phaser unit loaded with gain (G) and another loaded with equalized loss (L = 1/G) provide symmetric amplitudes (about 0 dB) and identical group delays. Cascading such gain and loss pair yields real all-pass amplitude. Moreover, the group delay can be tuned by the gain and loss. Chapter 3 introduces the gain-loss equalization concept, mathematically presents the device modeling, and experimentally demonstrated the prototype

Synthesis and monolithic integration of analogue signal processing networks

Data traffic of future 5G telecommunication systems is projected to increase 10 000-fold compared to current rates. 5G fronthaul links are therefore expected to operate in the mm-wave spectrum with some preliminary International Telecommunication Union specifications set for the 71-76 and 81-86 GHz bands. Processing 5 GHz as a single contiguous band in real-time, using existing digital signal processing (DSP) systems, is exceedingly challenging. A similar challenge exists in radio astronomy, with the Square Kilometer Array project expecting data throughput rates of 15 Tbits/s at its completion. Speed improvements on existing state-of-the-art DSPs of 2-3 orders of magnitude are therefore required to meet future demands. One possible mitigating approach to processing wideband data in real-time is to replace some DSP blocks with analog signal processing (ASP) equivalents, since analogue devices outperform their digital counterparts in terms of cost, power consumption and the maximum attainable bandwidth. The fundamental building block of any ASP is an all-pass network of prescribed response, which can always be synthesized by cascaded first- and second-order all-pass sections (with two cascaded first-order sections being a special case of the latter). The monolithic integration of all-pass networks in commercial CMOS and BiCMOS technology nodes is a key consideration for commercial adaptation of ASPs, since it supports mass production at reduced costs and operating power requirements, making the ASP approach feasible. However, this integration has presented a number of yet unsolved challenges. Firstly, the state-of-the-art methods for synthesizing quasi-arbitrary group delay functions using all-pass elements lack a theoretical synthesis procedure that guarantees minimum-order networks. In this work an analytically-based solution to the synthesis problem is presented that produces an all-pass network with a response approximating the required group delay to within an arbitrary minimax error. This method is shown to work for any physical realization of second-order all-pass elements, is guaranteed to converge to a global optimum solution without any choice of seed values as an input, and allows synthesis of pre-defined networks described either analytically or numerically. Secondly, second-order all-pass networks are currently primarily implemented in off-chip planar media, which is unsuited for high volume production. Component sensitivity, process tolerances and on-chip parasitics often make proposed on-chip designs impractical. Consequently, to date, no measured results of a dispersive on-chip second-order all-pass network suitable for ASP applications (delay Q-value (QD) larger than 1) have been presented in either CMOS or BiCMOS technology nodes. In this work, the first ever on-chip CMOS second-order all-pass network is proposed with a measured QD-value larger than 1. Measurements indicate a post-tuning bandwidth of 280 MHz, peak-to-nominal delay variation of 10 ns, QD-value of 1.15 and magnitude variation of 3.1 dB. An active on-chip mm-wave second-order all-pass network is further demonstrated in a 130 nm SiGe BiCMOS technology node with a bandwidth of 40 GHz, peak-to-nominal delay of 62 ps, QD-value of 3.6 and a magnitude ripple of 1.4 dB. This is the first time that measurement results of a mm-wave bandwidth second-order all-pass network have been reported. This work therefore presents the first step to monolithically integrating ASP solutions to conventional DSP problems, thereby enabling ultra-wideband signal processing on-chip in commercial technology nodes.Thesis (PhD)--University of Pretoria, 2018.Square Kilometer Array (SKA) project - postgraduate scholarshipElectrical, Electronic and Computer EngineeringPhDUnrestricte

Altering regional development for sustainability: Lessons learned from strategic communications of RCE Saskatchewan (Canada) with government

An important part of successful strategies for sustainable development involves altering (or, in some cases, preventing) proposals for development that are unsustainable or have significant opportunity costs relative to more sustainable alternatives. In modern democracies, development proposals normally require formal public approvals (whether at the municipal, provincial/state, or national level) with opportunities for public and specialist input and oversight as well as legal remedies where due processes are not followed. This creates an important locus for ESD, specifically educational interventions by Regional Centers of Expertise on education for sustainable development (RCEs). RCEs are able to rapidly mobilize local, regional, and global expertise to engage such processes, frequently where there are narrow time frames and complex mechanisms for public input. The paper will use a case studies approach examining strategic communications of RCE Saskatchewan with various levels of government in proposed developments within its region in Western Canada. Despite a primary commitment of governments in the RCE Saskatchewan region to economic growth with a more limited role for sustainable development, the RCE has successfully contributed to substantially altering unsustainable development proposals in a range of areas since its acknowledgment in 2007. These proposals have included forest clear-cutting, large-scale water diversions, agricultural drainage, nuclear power, road construction, and potash mining. The RCE's interventions have been modest, involving letters and formal submissions through existing government channels aimed at public officials or elected representatives involved in key stages of decision making. This paper will document some of the main elements of the formal RCE correspondence that has lead to its strategic effectiveness including the RCE's ability to draw upon independent scholarly knowledge (including expertise about governmental processes) and legitimization of local sustainability expertise. These interventions have enabled local learning, modifications of specific development proposals, and, in some cases, system-wide transformations. Importantly, however, it highlights how an older form of university scholarship associated with the rise of the humanities, namely the art of formal correspondence or letter writing, can be customized to the goal of regional education for sustainable development

Federal Register

Daily publication of the U.S. Office of the Federal Register contains rules and regulations, proposed legislation and rule changes, and other notices, including "Presidential proclamations and Executive Orders, Federal agency documents having general applicability and legal effect, documents required to be published by act of Congress, and other Federal agency documents of public interest" (p. ii). Table of Contents starts on page iii

2005 BRAC Commission

Contains notes, emails and other material presented to the Senate Armed Services Committee on September 15, 2005 upon their request