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

Real-Time Dispersion Code Multiple Access (DCMA) for High-Speed Wireless Communications

We model, demonstrate and characterize Dispersion Code Multiple Access (DCMA) and hence show the applicability of this purely analog and real-time multiple access scheme to high-speed wireless communications. We first mathematically describe DCMA and show the appropriateness of Chebyshev dispersion coding in this technology. We next provide an experimental proof-of-concept in a 2 X 2 DCMA system. Finally,we statistically characterize DCMA in terms of bandwidth, dispersive group delay swing, system dimension and signal-to-noise ratio

Flexible-Resolution, Arbitrary-Input and Tunable Rotman Lens Spectrum Decomposer (RL-SD)

We present an enhanced design -- in terms of resolution flexibility, input port position arbitrariness and frequency-range tunability -- of the planar Rotman lens spectrum decomposer (RL-SD). This enhancement is achieved by manipulating the output port locations through proper sampling of the frequency-position law of the RL-SD, inserting a calibration array compensating for frequency deviation induced by input modification and introducing port switching, respectively. A complete design procedure is provided and two enhanced RL-SD prototypes, with uniform port distribution and uniform frequency resolution, respectively, are numerically and experimentally demonstrated

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

Generalized Coupled-line All-Pass Phasers

Generalized coupled-line all-pass phasers, based on transversally-cascaded (TC), longitudinally-cascaded (LC) and hybrid-cascaded (HC) coupled transmission line sections, are presented and demonstrated using analytical, full-wave and experimental results. It is shown that for N commensurate coupled-line sections, LC and TC phasers exhibit N group delay peaks per coupled-line section harmonic frequency band, in contrast to the TC configuration, which exhibits only one peak within this band. It is also shown that for a given maximum achievable coupling-coefficient, the HC configuration provides the largest group delay swing. A wave-interference analysis is finally applied to the various coupled-line phasers, explaining their unique group delay characteristics based on physical wave-propagation mechanisms.Comment: 10 pages, 11 figure