1,859 research outputs found
An Adaptive Design Methodology for Reduction of Product Development Risk
Embedded systems interaction with environment inherently complicates
understanding of requirements and their correct implementation. However,
product uncertainty is highest during early stages of development. Design
verification is an essential step in the development of any system, especially
for Embedded System. This paper introduces a novel adaptive design methodology,
which incorporates step-wise prototyping and verification. With each adaptive
step product-realization level is enhanced while decreasing the level of
product uncertainty, thereby reducing the overall costs. The back-bone of this
frame-work is the development of Domain Specific Operational (DOP) Model and
the associated Verification Instrumentation for Test and Evaluation, developed
based on the DOP model. Together they generate functionally valid test-sequence
for carrying out prototype evaluation. With the help of a case study 'Multimode
Detection Subsystem' the application of this method is sketched. The design
methodologies can be compared by defining and computing a generic performance
criterion like Average design-cycle Risk. For the case study, by computing
Average design-cycle Risk, it is shown that the adaptive method reduces the
product development risk for a small increase in the total design cycle time.Comment: 21 pages, 9 figure
Satellite Navigation for the Age of Autonomy
Global Navigation Satellite Systems (GNSS) brought navigation to the masses.
Coupled with smartphones, the blue dot in the palm of our hands has forever
changed the way we interact with the world. Looking forward, cyber-physical
systems such as self-driving cars and aerial mobility are pushing the limits of
what localization technologies including GNSS can provide. This autonomous
revolution requires a solution that supports safety-critical operation,
centimeter positioning, and cyber-security for millions of users. To meet these
demands, we propose a navigation service from Low Earth Orbiting (LEO)
satellites which deliver precision in-part through faster motion, higher power
signals for added robustness to interference, constellation autonomous
integrity monitoring for integrity, and encryption / authentication for
resistance to spoofing attacks. This paradigm is enabled by the 'New Space'
movement, where highly capable satellites and components are now built on
assembly lines and launch costs have decreased by more than tenfold. Such a
ubiquitous positioning service enables a consistent and secure standard where
trustworthy information can be validated and shared, extending the electronic
horizon from sensor line of sight to an entire city. This enables the
situational awareness needed for true safe operation to support autonomy at
scale.Comment: 11 pages, 8 figures, 2020 IEEE/ION Position, Location and Navigation
Symposium (PLANS
Millimetre-wave and Terahertz Electronics
Overview:
The basic thesis for the advancement of millimetre-wave and terahertz electronics is
represented in four sections: Signal Processing, Component Design and Realization,
Modelling and Materials, and Paradigm Shift. The first section is at system and circuit levels
and reports on complex signal process functions that have been performed directly on the
millimetre-wave carrier signal, intended for realizing low-cost and adaptive communications
and radar systems architectures. The second section is at circuit and component levels and
reports on techniques for the design and realization of low-loss passives for use at millimetrewave
frequencies. The third section is at component and material levels and reports on
modelling techniques for passives for use at both millimetre-wave and terahertz frequencies.
Finally, the fourth section introduces a revolutionary new technology that represents a
paradigm shift in the way millimetre-wave and terahertz electronics (i.e. components, circuits
and systems) can be implemented. As found with the new generation of mobile phone
handsets, a fusion of two extreme technologies can take place; here, complex signal processing
operations could be performed both directly on the carrier signal and with the use of a spatial
light modulator.
Based on a selection of 20 papers (co-)authored by the candidate †b, and published over a
period of 15 years, it will be seen that a coherent theme runs throughout this body of work, for
the advancement of knowledge in millimetre-wave and terahertz electronics
Efficient spectrum-handoff schemes for cognitive radio networks
Radio spectrum access is important for terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations. The services offered by terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations have evolved due to technological advances. They are expected to meet increasing users' demands which will require more spectrum. The increasing demand for high throughput by users necessitates allocating additional spectrum to terrestrial wireless networks. Terrestrial radio astronomy observations s require additional bandwidth to observe more spectral windows. Commercial earth observation requires more spectrum for enhanced transmission of earth observation data. The evolution of terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations leads to the emergence of new interference scenarios. For instance, terrestrial wireless networks pose interference risks to mobile ground stations; while inter-satellite links can interfere with terrestrial radio astronomy observations. Terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations also require mechanisms that will enhance the performance of their users. This thesis proposes a framework that prevents interference between terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations when they co-exist; and enhance the performance of their users. The framework uses the cognitive radio; because it is capable of multi-context operation. In the thesis, two interference avoidance mechanisms are presented. The first mechanism prevents interference between terrestrial radio astronomy observations and inter-satellite links. The second mechanism prevent interference between terrestrial wireless networks and the commercial earth observation ground segment. The first interference reductionmechanism determines the inter-satellite link transmission duration. Analysis shows that interference-free inter-satellite links transmission is achievable during terrestrial radio astronomy observation switching for up to 50.7 seconds. The second mechanism enables the mobile ground station, with a trained neural network, to predict the terrestrial wireless network channel idle state. The prediction of the TWN channel idle state prevents interference between the terrestrial wireless network and the mobile ground station. Simulation shows that incorporating prediction in the mobile ground station enhances uplink throughput by 40.6% and reduces latency by 18.6%. In addition, the thesis also presents mechanisms to enhance the performance of the users in terrestrial wireless network, commercial earth observations and terrestrial radio astronomy observations. The thesis presents mechanisms that enhance user performance in homogeneous and heterogeneous terrestrial wireless networks. Mechanisms that enhance the performance of LTE-Advanced users with learning diversity are also presented. Furthermore, a future commercial earth observation network model that increases the accessible earth climatic data is presented. The performance of terrestrial radio astronomy observation users is enhanced by presenting mechanisms that improve angular resolution, power efficiency and reduce infrastructure costs
A CubeSat Power System Implementing a Zero Voltage Switching Resonant Buck Converter Design with Low Electronic & Radio Frequency Noise
Noise from power systems can be a limiting factor in how well scientific instruments on CubeSats can perform. Instruments such as microwave radiometers which are on TROPICS, TEMPEST-D, and IceCube, or wide-band software defined radios such as those used on AERO/VISTA for Earth auroral hiss observations, or precipitation instruments used on RainCube are all affected by electronic and radio frequency (RF) noise. Current hybrid DC/DC converter technologies can also be prone to failure and anomalies during flight. The GRACE mission had the converter fail due to high temperatures, which caused a reduction in switching frequency. This research project will provide a way for CubeSat power subsystems to become more optimized and efficient by reducing the noise produced, enabling CubeSats to support a wider range of science missions. This paper presents a design for a CubeSat power subsystem that uses a phase-locking control scheme where the voltage ripple and RF noise can be significantly reduced so that the power converter does not affect the CubeSat instruments. CubeSats are now returning valuable scientific data and can improve temporal and spatial coverage. Optimizing CubeSat power subsystems enables its payload to become more effective
White Paper for Research Beyond 5G
The documents considers both research in the scope of evolutions of the 5G systems (for the period around 2025) and some alternative/longer term views (with later outcomes, or leading to substantial different design choices). This document reflects on four main system areas: fundamental theory and technology, radio and spectrum management; system design; and alternative concepts. The result of this exercise can be broken in two different strands: one focused in the evolution of technologies that are already ongoing development for 5G systems, but that will remain research areas in the future (with “more challenging” requirements and specifications); the other, highlighting technologies that are not really considered for deployment today, or that will be essential for addressing problems that are currently non-existing, but will become apparent when 5G systems begin their widespread deployment
- …