Design Of Polynomial-based Filters For Continuously Variable Sample Rate Conversion With Applications In Synthetic Instrumentati

In this work, the design and application of Polynomial-Based Filters (PBF) for continuously variable Sample Rate Conversion (SRC) is studied. The major contributions of this work are summarized as follows. First, an explicit formula for the Fourier Transform of both a symmetrical and nonsymmetrical PBF impulse response with variable basis function coefficients is derived. In the literature only one explicit formula is given, and that for a symmetrical even length filter with fixed basis function coefficients. The frequency domain optimization of PBFs via linear programming has been proposed in the literature, however, the algorithm was not detailed nor were explicit formulas derived. In this contribution, a minimax optimization procedure is derived for the frequency domain optimization of a PBF with time-domain constraints. Explicit formulas are given for direct input to a linear programming routine. Additionally, accompanying Matlab code implementing this optimization in terms of the derived formulas is given in the appendix. In the literature, it has been pointed out that the frequency response of the Continuous-Time (CT) filter decays as frequency goes to infinity. It has also been observed that when implemented in SRC, the CT filter is sampled resulting in CT frequency response aliasing. Thus, for example, the stopband sidelobes of the Discrete-Time (DT) implementation rise above the CT designed level. Building on these observations, it is shown how the rolloff rate of the frequency response of a PBF can be adjusted by adding continuous derivatives to the impulse response. This is of great advantage, especially when the PBF is used for decimation as the aliasing band attenuation can be made to increase with frequency. It is shown how this technique can be used to dramatically reduce the effect of alias build up in the passband. In addition, it is shown that as the number of continuous derivatives of the PBF increases the resulting DT implementation more closely matches the Continuous-Time (CT) design. When implemented for SRC, samples from a PBF impulse response are computed by evaluating the polynomials using a so-called fractional interval, µ. In the literature, the effect of quantizing µ on the frequency response of the PBF has been studied. Formulas have been derived to determine the number of bits required to keep frequency response distortion below prescribed bounds. Elsewhere, a formula has been given to compute the number of bits required to represent µ to obtain a given SRC accuracy for rational factor SRC. In this contribution, it is shown how these two apparently competing requirements are quite independent. In fact, it is shown that the wordlength required for SRC accuracy need only be kept in the µ generator which is a single accumulator. The output of the µ generator may then be truncated prior to polynomial evaluation. This results in significant computational savings, as polynomial evaluation can require several multiplications and additions. Under the heading of applications, a new Wideband Digital Downconverter (WDDC) for Synthetic Instruments (SI) is introduced. DDCs first tune to a signal\u27s center frequency using a numerically controlled oscillator and mixer, and then zoom-in to the bandwidth of interest using SRC. The SRC is required to produce continuously variable output sample rates from a fixed input sample rate over a large range. Current implementations accomplish this using a pre-filter, an arbitrary factor resampler, and integer decimation filters. In this contribution, the SRC of the WDDC is simplified reducing the computational requirements to a factor of three or more. In addition to this, it is shown how this system can be used to develop a novel computationally efficient FFT-based spectrum analyzer with continuously variable frequency spans. Finally, after giving the theoretical foundation, a real Field Programmable Gate Array (FPGA) implementation of a novel Arbitrary Waveform Generator (AWG) is presented. The new approach uses a fixed Digital-to-Analog Converter (DAC) sample clock in combination with an arbitrary factor interpolator. Waveforms created at any sample rate are interpolated to the fixed DAC sample rate in real-time. As a result, the additional lower performance analog hardware required in current approaches, namely, multiple reconstruction filters and/or additional sample clocks, is avoided. Measured results are given confirming the performance of the system predicted by the theoretical design and simulation

Noise Characterization and Emulation for Low-Voltage Power Line Channels between 150 kHz and 10 MHz

Characterization and emulation of power line noise have attracted interest since long, in both narrowband and broadband applications. Based on existing models, this paper presents a systematic approach to extract and parameterize each subtype of low-voltage (LV) power line noise between 150 kHz and 10 MHz. Based on the characterization, a FPGA-based emulator is proposed to emulate power line noise scenarios flexibly. A LV power line noise measuring platform is also presented with sample measurements and their emulation

Emulation of Narrowband Powerline Data Transmission Channels and Evaluation of PLC Systems

This work proposes advanced emulation of the physical layer behavior of NB-PLC channels and the application of a channel emulator for the evaluation of NB-PLC systems. In addition, test procedures and reference channels are proposed to improve efficiency and accuracy in the system evaluation and classification. This work shows that the channel emulator-based solution opens new ways toward flexible, reliable and technology-independent performance assessment of PLC modems

Digital and Mixed Domain Hardware Reduction Algorithms and Implementations for Massive MIMO

Emerging 5G and 6G based wireless communications systems largely rely on multiple-input-multiple-output (MIMO) systems to reduce inherently extensive path losses, facilitate high data rates, and high spatial diversity. Massive MIMO systems used in mmWave and sub-THz applications consists of hundreds perhaps thousands of antenna elements at base stations. Digital beamforming techniques provide the highest flexibility and better degrees of freedom for phased antenna arrays as compared to its analog and hybrid alternatives but has the highest hardware complexity. Conventional digital beamformers at the receiver require a dedicated analog to digital converter (ADC) for every antenna element, leading to ADCs for elements. The number of ADCs is the key deterministic factor for the power consumption of an antenna array system. The digital hardware consists of fast Fourier transform (FFT) cores with a multiplier complexity of (N log2N) for an element system to generate multiple beams. It is required to reduce the mixed and digital hardware complexities in MIMO systems to reduce the cost and the power consumption, while maintaining high performance. The well-known concept has been in use for ADCs to achieve reduced complexities. An extension of the architecture to multi-dimensional domain is explored in this dissertation to implement a single port ADC to replace ADCs in an element system, using the correlation of received signals in the spatial domain. This concept has applications in conventional uniform linear arrays (ULAs) as well as in focal plane array (FPA) receivers. Our analysis has shown that sparsity in the spatio-temporal frequency domain can be exploited to reduce the number of ADCs from N to where . By using the limited field of view of practical antennas, multiple sub-arrays are combined without interferences to achieve a factor of K increment in the information carrying capacity of the ADC systems. Applications of this concept include ULAs and rectangular array systems. Experimental verifications were done for a element, 1.8 - 2.1 GHz wideband array system to sample using ADCs. This dissertation proposes that frequency division multiplexing (FDM) receiver outputs at an intermediate frequency (IF) can pack multiple (M) narrowband channels with a guard band to avoid interferences. The combined output is then sampled using a single wideband ADC and baseband channels are retrieved in the digital domain. Measurement results were obtained by employing a element, 28 GHz antenna array system to combine channels together to achieve a 75% reduction of ADC requirement. Implementation of FFT cores in the digital domain is not always exact because of the finite precision. Therefore, this dissertation explores the possibility of approximating the discrete Fourier transform (DFT) matrix to achieve reduced hardware complexities at an allowable cost of accuracy. A point approximate DFT (ADFT) core was implemented on digital hardware using radix-32 to achieve savings in cost, size, weight and power (C-SWaP) and synthesized for ASIC at 45-nm technology

System-Level Design of All-Digital LTE / LTE-A Transmitter Hardware

This thesis presents a detailed system-level analysis of an all-digital transmitter hardware based on the Direct-Digital RF-Modulator (DDRM). The purpose of the presented analysis is to evaluate whether this particular transmitter architecture is suitable to be used in LTE / LTE-A mobile phones. The DDRM architecture is based on the Radio Frequency Digital-to-Analog Converter (RF-DAC), whose system-level characteristics are investigated in this work through mathematical analysis and MATLAB simulations. In particular, a new analytical model for the timing error in the distributed upconversion is developed and verified. Moreover, this thesis reviews the LTE and LTE-A standards, and describes how a baseband environment for signal generation/demodulation can be implemented in MATLAB. The presented system enables much more flexibility with respect to current commercial softwares like Agilent Signal Studio. Simulation results show that the most challenging specification to meet is the out-of-band noise floor, because of the stringent linearity and timing requirements posed on the RF-DAC. This suggests that new means of reducing the out-of-band noise in all-digital transmitters should be researched, in order not to make their design more complicated than for their analog counterpart

The design and implementation of an acoustic phased array transmitter for the demonstration of MIMO techniques

MIMO radar algorithms are the latest generation of techniques that can be applied to array radars. They offer the potential to improve the radar resolution, increase the number of targets that can be identified and give added flexibility in beampattern design. However, little experimental data demonstrating MIMO radar is available because radar arrays are already expensive systems and MIMO extends the com- plexity and cost further. An acoustic array, which works on the same principles as a radio frequency radar array, can be built at a fraction of the cost of a real radar system. The novel contribution of this project was the demonstration ofMIMO radar techniques on an acoustic array, which was designed and built for this purpose. To achieve the project objectives, the theory of traditional phased array radar techniques and MIMO techniques was researched. The phased array and MIMO techniques were also simulated under narrowband and wideband conditions, and the strengths and weaknesses of each were highlighted. This was followed by the design and implementation of a low cost audible acoustic transmitter array to be used with an existing receiver array to demonstrate the investigated array radar techniques. Finally, the techniques were tested on the hardware platform. The simulation and hardware test results were used to evaluate and compare the performance of phased array and MIMO radar techniques. The beampattern design flexibility that is offered by MIMO radar was demonstrated with the transmission and measurement of omnidirectional, single-lobed and multi-lobed MIMO beampat- terns. Also, parameter estimation experiments were performed where phased array and MIMO radar signals were transmitted. Phased array techniques were shown to be simple, effective and robust. The MIMO Capon, APES and GLRT parameter estimation techniques were shown to be sensitive to the type of signals transmitted, and in most cases, the added complexity of these techniques did not lead to improved target parameter estimation results. However, the MIMO technique of transmitter beamforming on reception gave high resolution target range and angle estimates, living up to the expectations placed on MIMO radar

Techniques for Wideband All Digital Polar Transmission

abstract: Modern Communication systems are progressively moving towards all-digital transmitters (ADTs) due to their high efficiency and potentially large frequency range. While significant work has been done on individual blocks within the ADT, there are few to no full systems designs at this point in time. The goal of this work is to provide a set of multiple novel block architectures which will allow for greater cohesion between the various ADT blocks. Furthermore, the design of these architectures are expected to focus on the practicalities of system design, such as regulatory compliance, which here to date has largely been neglected by the academic community. Amongst these techniques are a novel upconverted phase modulation, polyphase harmonic cancellation, and process voltage and temperature (PVT) invariant Delta Sigma phase interpolation. It will be shown in this work that the implementation of the aforementioned architectures allows ADTs to be designed with state of the art size, power, and accuracy levels, all while maintaining PVT insensitivity. Due to the significant performance enhancement over previously published works, this work presents the first feasible ADT architecture suitable for widespread commercial deployment.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

Experimental demonstration of PAM-DWMT for passive optical network

We experimentally demonstrate a discrete wavelet multitone (DWMT) modulation scheme based on pulse amplitude modulation (PAM) for next generation passive optical network (PON), which offers high tolerance against chromatic dispersion, high spectral efficiency, low peak to average power ratio (PAPR) and low side lobes. The experimental results show the chromatic dispersion induced power penalties are negligible after 20km fiber transmission. Compared with orthogonal frequency division multiplexing (OFDM), DWMT offers a better receiver sensitivity

Enhanced PON Infrastructure Enabled by Silicon Photonics

Les systèmes de courte portée et de détection directe sont le dernier/premier kilomètre de la fourniture des services Internet d'aujourd'hui. Deux cas d'application sont abordés dans cette thèse, l'un concerne l'amélioration des performances des services Internet par la Fibre-To-TheHome ou les réseaux optiques passifs (PONs). L'autre est le radio access network (RAN) pour le fronthaul. Notre objectif pour RAN est de superposer les signaux 5G sur une infrastructure PON. Nous démontrons expérimentalement la génération d'un signal de répartition multiplexée de fréquences orthogonales (OFDM) à bande latérale unique en utilisant un modulateur IQ sur puce basé sur les photoniques au silicium à micro-anneau. Il s'agit d'une solution à coût bas permettant aux PONs d'augmenter les débits de données grâce à l'utilisation d'OFDM. Nous avons généré un signal OFDM à large bande avec un ratio de suppression de bande latérale de plus de 18 dB. Afin de confirmer la robustesse de la dispersion chromatique (CD), nous transmettons le signal généré OFDM SSB dans plus de 20 km de fibre de monomode standard. Aucun fading induit par la CD n'a été observé et le taux d'erreur sur les bits était bon. Nous proposons une solution de photoniques au silicium pour un réseau optique passif afin de mitiger l'interférence de battement signal-signal (SSBI) dans la transmission OFDM, et de récupérer une partie des porteuses de la liaison descendante pour une utilisation dans la liaison montante. Le sous-système recrée les interférences à une entrée du détecteur équilibré ; le signal de données corrompu par SSBI est à la deuxième entrée. L'annulation se produit via la soustraction dans la détection équilibrée. Comme notre solution de photoniques au silicium (SiP) ne peut pas filtrer les signaux idéalement, nous examinons un facteur d'échelle introduit dans la détection équilibrée qui peut balancer les effets de filtrage non idéaux. Nous montrons expérimentalement l'annulation de l'interférence donne de bonnes performances même avec une porteuse faible, soit pour un ratio porteuse/signal ultra bas de 0 dB. Bien que notre solution soit sensible aux effets de la température, notre démonstration expérimentale montre que le réglage de la fréquence résonante peut dériver jusqu'à 12 GHz de la valeur ciblée et présenter toujours de bonnes performances. Nous effectuons des simulations extensives du schéma d'annulation SSBI proposé, et suggérons une diverse conception polarisée pour le sous-système SiP. Nous examinons via la simulation la vulnérabilité à la variation de température et introduisons une nouvelle métrique de performance : Q-facteur minimum garanti. Nous nous servons de cette métrique pour évaluer la robustesse d'annulation SSBI contre la dérive de fréquence induite par les changements de température. Nous maximisons l'efficacité spectrale sous différentes conditions du système en balayant les paramètres de conception contrôlables. Finalement, les résultats de la simulation du système fournissent des indications sur la conception du résonateur micro-anneau, ainsi que sur le choix de la bande de garde et du format de modulation pour obtenir la plus grande efficacité spectrale. Finalement, nous nous concentrons sur la superposition des signaux 5G sur une infrastructure PON pour RAN. Nous expérimentalement validons un sous-système photonique au silicium conçu pour les réseaux optiques passifs avec réutilisation de porteuses et compatibilité radiosur-fibre (RoF) analogique 5G. Le sous-système permet la détection simultanée des signaux RoF et du signal PON transmis dans une seule tranche assignée de longueur d'onde. Tout en maintenant une qualité suffisante de détection des signaux RoF et PON, il n'y a que la puissance minimale de la porteuse qui est extraite pour chaque détection, ce qui conserve ainsi la puissance de la porteuse pour la modulation de liaison montante. Nous réalisons une suppression efficace du signal de liaison descendante en laissant une porteuse propre et forte pour la remodulation. Nous démontrons expérimentalement le signal RoF de liaison montante via un modulateur à micro-anneau. Nous avons détecté avec succès un signal à large bande de 8 GHz et cinq signaux RoF de 125 MHz simultanément. Et deux signaux RoF de 125 MHz sont remodulés sur la même porteuse. Le signal RoF de liaison montante généré est de 13 dB de plus que les signaux de liaison descendante, ce qui indique leur robustesse contre la diaphonie des signaux résiduels de la liaison descendante.Short reach, direct detection systems are the last/first mile of today's internet service provision. Two use cases are addressed in this thesis, one is for enhancing performance of Internet services on fiber-to-the-home or passive optical networks (PON). The other is radio access networks (RAN) for fronthaul. Our focus for RAN is to overlay 5G signals on a PON infrastructure. We experimentally demonstrate the generation of a single-sideband orthogonal frequency division multiplexed (OFDM) signal using an on-chip silicon photonics microring-based IQ modulator. This is a low cost solution enabling PONs to increase data rates through the use of OFDM. We generated a wideband OFDM signal with over 18 dB sideband suppression ratio. To confirm chromatic dispersion (CD) robustness, we transmit the generated SSB OFDM signal over 20 km of standard single mode fiber. No CD-induced fading was observed and bit error rate was good. We propose a silicon photonics solution for a passive optical network to mitigate signal-signal beat interference (SSBI) in OFDM transmission, and to recuperate a part of the downlink carrier for use in the uplink. The subsystem recreates the interference at one balanced detector input; the data signal corrupted with SSBI is at the second input. Cancellation occurs via subtraction in the balanced detection. As our silicon photonics (SiP) solution cannot filter the signals ideally, we examine a scaling factor to be introduced to the balanced detection that can trade-off the non-ideal filtering effects. We show experimentally that the interference is cancelled, allowing good performance even with a weak carrier, that is, for ultra low carrier to signal ratio of 0 dB. Although our solution is sensitive to temperature effects, our experimental demonstration shows the tuning of the resonant frequency can drift by as much as 12 GHz from the targeted value and still provide good performance. We perform extensive simulations of the proposed SSBI cancellation scheme, and suggest a polarization diverse design for the SiP subsystem. We examine via simulation the vulnerability to temperature variation and introduce a new performance metric: minimum guaranteed Qfactor. We use this metric to evaluate the SSBI cancellation robustness against the frequency drift induced by temperature changes. We maximize the spectral efficiency under different system conditions by sweeping the controllable design parameters. Finally the system simulation results provide guidance on the microring resonator design, as well as choice of guard band and modulation format to achieve the highest spectral efficiency. Finally, we turn to focus on overlay 5G signals on a PON infrastructure for RAN. We experimentally validate a silicon photonic subsystem designed for passive optical networks with carrier reuse and 5G analog radio-over-fiber (RoF) compatibility. The subsystem enables the simultaneous detection of RoF signals and a PON signal transmitted in a single assigned wavelength slot. While maintaining sufficient quality of RoF and PON signal detection, only the minimum carrier power is leached off for each detection, thus conserving carrier power for uplink modulation. We realize effective downlink signal suppression to leave a clean and strong carrier for remodulation. We demonstrate experimentally the RoF uplink signal via a micro ring modulator. We successfully detected an 8 GHz broadband signal and five 125 MHz RoF signals simultaneously. And two 125 MHz radio over fiber signals are remodulated onto the same carrier. The generated uplink RoF signal is 13 dB over the downlink signals, indicating their robustness against the crosstalk from residual downlink signals