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A multi-protocol quantum key distribution transmitter
Quantum key distribution (QKD) is a technology that allows two users to communicate with
theoretically perfect security using standard optical fibres. This is possible by transmitting
the key on single photons, meaning a measurement by an eavesdropper disturbs the system
in a way observable to the legitimate parties. The technology has advanced since the first
protocol proposed in 1984, to the stage where there are now many protocols that can be
experimentally implemented. These protocols have allowed secure keys to be generated over
distances greater than 400 km and with secure key rates over 10 Mbit/s.
In a metropolitan QKD network, it would be desirable for as many users to be connected
as possible. Unfortunately, each protocol comes with different requirements on the transmitter
and receiver. Even within a single protocol, different clock rates can require individualised
transmitter and receiver hardware. This prohibits users from communicating with all receivers,
unless they have complex transmitters with hardware for many protocols.
This thesis develops a transmitter for practical QKD that is able to adapt to a number of
different protocols with no changes to the hardware. The transmitter works using optical
injection locking, where a pulse preparation laser adopts the phase of a phase preparation
laser. Controlling the phase and intensity of the pulses in this way removes the side channel
ordinarily present with direct modulation, in that the phase, intensity and frequency simultaneously
change in response to an applied current. The cavity-enhanced electro-optic effect
allows for the first demonstration of sub-volt half-wave phase modulation at high clock rates.
The transmitter successfully demonstrates phase encoding, intensity encoding and on-demand
phase randomisation. This allows for the experimental realisation and direct comparison
of different QKD protocols, including one that has never before been implemented due to
experimental complexity.
A stable intensity modulator is also developed, based on a Sagnac interferometer. This
removes a side channel in QKD systems and integrates well with the directly-modulated
quantum transmitter. This development also means that the transmitter can implement all
current two-party QKD protocols based on weak coherent pulses.
The transmitter has the potential to become the standard transmitter for future quantum
communication networks due to its stability, versatility and power efficiency. The design
could also be demonstrated on a photonic chip, making it compact enough to fit in small
transmitter units.Royal Commission for the Exhibition of 1851
Toshiba Research Europe Lt
A digital polar transmitter for multi-band OFDM Ultra-WideBand
Linear power amplifiers used to implement the Ultra-Wideband standard must be
backed off from optimum power efficiency to meet the standard specifications and
the power efficiency suffers. The problem of low efficiency can be mitigated by polar
modulation. Digital polar architectures have been employed on numerous wireless
standards like GSM, EDGE, and WLAN, where the fractional bandwidths achieved
are only about 1%, and the power levels achieved are often in the vicinity of 20 dBm.
Can the architecture be employed on wireless standards with low-power and high
fractional bandwidth requirements and yet achieve good power efficiency?
To answer these question, this thesis studies the application of a digital polar transmitter
architecture with parallel amplifier stages for UWB. The concept of the digital
transmitter is motivated and inspired by three factors. First, unrelenting advances
in the CMOS technology in deep-submicron process and the prevalence of low-cost
Digital Signal processing have resulted in the realization of higher level of integration
using digitally intensive approaches. Furthermore, the architecture is an evolution
of polar modulation, which is known for high power efficiency in other wireless applications.
Finally, the architecture is operated as a digital-to-analog converter which
circumvents the use of converters in conventional transmitters.
Modeling and simulation of the system architecture is performed on the Agilent Advanced
Design System Ptolemy simulation platform. First, by studying the envelope
signal, we found that envelope clipping results in a reduction in the peak-to-average
power ratio which in turn improves the error vector magnitude performance (figure
of merit for the study). In addition, we have demonstrated that a resolution of three
bits suffices for the digital polar transmitter when envelope clipping is performed.
Next, this thesis covers a theoretical derivation for the estimate of the error vector
magnitude based on the resolution, quantization and phase noise errors. An analysis
on the process variations - which result in gain and delay mismatches - for a
digital transmitter architecture with four bits ensues. The above studies allow RF
designers to estimate the number of bits required and the amount of distortion that
can be tolerated in the system.
Next, a study on the circuit implementation was conducted. A DPA that comprises
7 parallel RF amplifiers driven by a constant RF phase-modulated signal and 7
cascode transistors (individually connected in series with the bottom amplifiers)
digitally controlled by a 3-bit digitized envelope signal to reconstruct the UWB
signal at the output. Through the use of NFET models from the IBM 130-nm
technology, our simulation reveals that our DPA is able to achieve an EVM of -
22 dB. The DPA simulations have been performed at 3.432 GHz centre frequency
with a channel bandwidth of 528 MHz, which translates to a fractional bandwidth
of 15.4%. Drain efficiencies of 13.2/19.5/21.0% have been obtained while delivering
-1.9/2.5/5.5 dBm of output power and consuming 5/9/17 mW of power.
In addition, we performed a yield analysis on the digital polar amplifier, based
on unit-weighted and binary-weighted architecture, when gain variations are introduced
in all the individual stages. The dynamic element matching method is also
introduced for the unit-weighted digital polar transmitter. Monte Carlo simulations
reveal that when the gain of the amplifiers are allowed to vary at a mean of 1 with a
standard deviation of 0.2, the binary-weighted architecture obtained a yield of 79%,
while the yields of the unit-weighted architectures are in the neighbourhood of 95%.
Moreover, the dynamic element matching technique demonstrates an improvement
in the yield by approximately 3%.
Finally, a hardware implementation for this architecture based on software-defined
arbitrary waveform generators is studied. In this section, we demonstrate that the error vector magnitude results obtained with a four-stage binary-weighted digital polar
transmitter under ideal combining conditions fulfill the European Computer Manufacturers
Association requirements. The proposed experimental setup, believed to
be the first ever attempted, confirm the feasibility of a digital polar transmitter architecture
for Ultra-Wideband. In addition, we propose a number of power combining
techniques suitable for the hardware implementation. Spatial power combining, in
particular, shows a high potential for the digital polar transmitter architecture.
The above studies demonstrate the feasibility of the digital polar architecture with
good power efficiency for a wideband wireless standard with low-power and high
fractional bandwidth requirements
Modulador de amplitude para amplificadores de rádio frequência
Mestrado em Engenharia Electrónica e TelecomunicaçõesEste trabalho enquadra-se na área de Electrónica para Telecomunicações.
A alteração dinâmica da fonte de alimentação do amplificador de potência
é uma das actuais soluções para ultrapassar o compromisso linearidade
rendimento. A construção do modulador para gerar a alimentação dinâmica
é crucial para a obtenção de um conjunto que cumpra os requisitos de
linearidade e rendimento. Os requisitos chave deste bloco são a largura de
banda e rendimento.
Neste trabalho foi feito o estudo das diversas abordagens e técnicas para
melhoramento da eficiência num amplificador de potência para rádio
frequência em particular as que recorrem a modelação da amplitude da
fonte de Alimentação (Seguidor de envolvente (SE), eliminação e restauro
de envolvente (EER) e modulação polar).
Efectuou-se o estudo dos moduladores de amplitude, seus requisitos chave
e técnicas de construção.
Foi implementado um modulador de amplitude capaz de fornecer 12W,
uma largura de banda para sinal fraco de 6MHz e um rendimento médio
para um sinal de CDMA2000FW de 57%. Este modulador permite a sua
utilização em outros standards tais como o EDGE e CDMA2000RV com
rendimento respectivamente de 73% e 67% respectivamente.This work is included in the area of electronics for telecommunications.
The dynamic shifting of the supply source of the power amplifier is
one of the nowadays solutions to overcome the efficiency linearity compromise.
The modulator construction to generate the dynamic supply
is crucial to obtain a set that meets the linearity and efficiency requirements.
A study of several approaches and techniques for improvement of efficiency
in a radio frequency power amplifier, particularly the ones that use the
power supply amplitude modulation (envelope tracking (ET), envelope
elimination and restoration (EER) e Polar modulation) was made.
The study of the amplitude Modulators, its key requirements and construction
techniques was be made.
An amplitude modulator able to supply 12W, a small signal bandwidth
of 6MHz and a 57% average efficiency for a CDMA2000RV signal was
implemented. This modulator allows it application in other standards like
EDGE and CDMA2000RV with respectably efficiency of 73% e 67%
Energy-Efficient Wireless Connectivity and Wireless Charging For Internet-of-Things (IoT) Applications
During the recent years, the Internet-of-Things (IoT) has been rapidly evolving. It is indeed the future of communication that has transformed Things of the real world into smarter devices. To date, the world has deployed billions of “smart” connected things. Predictions say there will be 10’s of billions of connected devices by 2025 and in our lifetime we will experience life with a trillion-node network. However, battery lifespan exhibits a critical barrier to scaling IoT devices. Replacing batteries on a trillion-sensor scale is a logistically prohibitive feat. Self-powered IoT devices seems to be the right direction to stand up to that challenge. The main objective of this thesis is to develop solutions to achieve energy-efficient wireless-connectivity and wireless-charging for IoT applications.
In the first part of the thesis, I introduce ultra-low power radios that are compatible with the Bluetooth Low-Energy (BLE) standard. BLE is considered as the preeminent protocol for short-range communications that support transmission ranges up to 10’s of meters. Number of low power BLE transmitter (TX) and receiver (RX) architectures have been designed, fabricated and tested in different planar CMOS and FinFET technologies. The low power operation is achieved by combining low power techniques in both the network and physical layers, namely: backchannel communication, duty-cycling, open-loop transmission/reception, PLL-less architectures, and mixer-first architectures. Further novel techniques have been proposed to further reduce the power the consumption of the radio design, including: a fast startup time and low startup energy crystal oscillators, an antenna-chip co-design approach for quadrature generation in the RF path, an ultra-low power discrete-time differentiator-based Gaussian Frequency Shift Keying (GFSK) demodulation scheme, an oversampling GFSK modulation/demodulation scheme for open loop transmission/reception and packet synchronization, and a cell-based design approach that allows automation in the design of BLE digital architectures. The implemented BLE TXs transmit fully-compliant BLE advertising packet that can be received by commercial smartphone.
In the second part of the thesis, I introduce passive nonlinear resonant circuits to achieve wide-band RF energy harvesting and robust wireless power transfer circuits. Nonlinear resonant circuits modeled by the Duffing nonlinear differential equation exhibit interesting hysteresis characteristics in their frequency and amplitude responses that are exploited in designing self-adaptive wireless charging systems. In the magnetic-resonance wireless power transfer scenario, coupled nonlinear resonators are proposed to maintain the power transfer level and efficiency over a range of coupling factors without active feedback control circuitry. Coupling factor depends on the transmission distance, lateral, and angular misalignments between the charging pad and the device. Therefore, nonlinear resonance extends the efficient charging zones of a wireless charger without the requirement for a precise alignment.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/169842/1/omaratty_1.pd
Proceedings of the 8th Precise Time and Time Interval (PTTI) Applications and Planning Meeting
The Proceedings contain the papers presented at the Eight Annual Precise Time and Tme Interval PTTI Applications and Planning Meeting. The edited record of the discussions following the papers and the panel discussions are also included. This meeting provided a forum for the exchange of information on precise time and frequency technology among members of the scientific community and persons with program applications. The 282 registered attendees came from various U.S. Government agencies, private industry, universities and a number of foreign countries were represented. In this meeting, papers were presented that emphasized: (1) definitions and international regulations of precise time sources and users, (2) the scientific foundations of Hydrogen Maser standards, the current developments in this field and the application experience, and (3) how to measure the stability performance properties of precise standards. As in the previous meetings, update and new papers were presented on system applications with past, present and future requirements identified
RFID multiantenna systems for wireless communications and sensing
Many scientific, industrial and medical applications require the measurement of different physical parameters in order to collect information about the spatially distributed status of some process. Very often this information needs to be collected remotely, either due to the spatial dispersion of the measurement points or due to their inaccessibility. A wireless embedded self-powered sensor may be a convenient solution to be placed at these inaccessible locations. This thesis is devoted to study the analytical relation governing the electromagnetic coupling between a reader and a embeddable self-powered sensor, based on radio frequency identification (RFID) technology, which is capable of wirelessly retrieving the status of physical parameters at a remote and inaccessible location. The physical parameter to be sensed may be the electromagnetic (EM) field existing at that location (primary measurement) or the indirect measurement of other parameters such as the temperature, humidity, etc. (secondary measurement). Given the simplicity of the RFID solution (highly embeddable properties, scavenging capabilities, penetration and radio coverage characteristics, etc.) the measurement can be done at a single location, or it can be extended to a set of measuring locations (an array or grid of sensors). The analytical relation is based on a reciprocity formulation studying the modulation of the scattered field by the embedded sensor in relation with the incident field, and allows to define a set of quality parameters of interest for the optimum design of the sensors. Particular attention is given to the scavenging circuitry as well as to the antenna design relevant to the sensing objective. In RFID tags, the existence of an RF harvesting section is an improvement with respect to conventional scattering field probes since it removes the need of DC biasing lines or optical fibers to modulate the sensor. However, this harvesting section introduces non-linearities in the response of the sensor, which requires a proper correction to use them as EM-field probes, although the characterization of the non-linearities of the RFID tag cannot be directly done using a conventional vector network analyzer (VNA), due to the requirements of an RFID protocol excitation. Due to this, this thesis proposes an alternative measurement approach that allows to characterize the different scattering states used for the modulation, in particular its non-linear behavior. In addittion, and taking this characterization as the starting point, this thesis proposes a new measurement setup for EM-field measurements based on the use of multiple tones to enlarge the available dynamic range, which is experimentally demonstrated in the measurement of a radiation pattern, as well as in imaging applications.
The RFID-based sensor response is electromagnetically sensitive to the dielectric properties of its close environment. However, the governing formulation for the response of the probe mixes together a set of different contributions, the path-loss, the antenna impedance, the loads impedance, etc. As a consequence, it is not possible to isolate each contribution from the others using the information available with a conventional RFID sensor. This thesis mathematically proposes and experimentally develops a modification of the modulation scheme to introduce a new set of multi-load scattering states that increases the information available in the response and properly isolate each term. Moreover, this thesis goes a step forward and introduces a new scattering state of the probe sensitive to temperature variations that do not depend on the environment characteristics. This new configuration enables robust environmental sensing in addition to EM-field measurements, and sensing variations of the dielectric properties of the environment
Radio Communications
In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks
Multichannel biomedical telemetry system using delta modulation
Telemetering of biomedical data from unrestrained subjects
requires a system to be compact, reliable and efficient.
A survey of the existing multi-channel biomedical telemetry
showed that most of the systems employ analogue or uncoded (digital)
techniques of encoding biomedical signals. These techniques are
less reliable, employ wider bandwidth and are difficult to implement
compared to the coded (digital) techniques of modulation.
A theoretical study of the coded techniques of modulation for
encoding biomedical signals showed-that pulse code modulation,
though more efficient, calls for extensive circuitry and makes it
expensive and difficult to implement. Delta modulation and
delta sigma modulation were found to be simpler, easier to Implement
and efficient. [Continues.
Advanced Syncom, volume 1 Summary report
Synchronous communications satellite configuration, instrumentation, handling and test equipment, and systems desig
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