Filetype
To be able to connect wirelessly to the internet is nowadays a part of everyday life and the number of wireless devices accessing wireless networks worldwide are increasing rapidly. However, with the increasing number of wireless devices and applications and the amount available bandwidth, spectrum shortage is an issue. A promising way to increase the amount of available spectrum is to utilize fre
Time-reversal (TR) signal processing has the potential to focus the transmitted signal at a desired receive (Rx) location in both space and time. At lower frequency bands, TR in conjunction with array antennas at transmit (Tx) or Rx has been shown to significantly improve its focusing performance relative to the case of single antennas at both link ends. This work for the first time investigates T
Optimization models related to designing and operating complex systems are mainly focused on some efficiency metrics such as response time, queue length, throughput, and cost. However, in systems which serve many entities there is also a need for respecting fairness: each system entity ought to be provided with an adequate share of the system's services. Still, due to system operations-dependant c
Open source components can be used as one type of software component in development of commercial software. In development using this type of component, potential open source components must first be identified, then specific components must be selected, and after that selected components should maybe be adapted before they are included in the developed product. A company using open source compone
Reference attribute grammars (RAGs) provide a practical declarative means to implement programming language compilers and other tools. RAGs have previously been extended to support nonterminal attributes (also known as higher-order attributes), circular attributes, and context-dependent declarative rewrites of the abstract syntax tree. In this previous work, interdependencies between these extensi
This paper presents the design of a digital PLL which uses a high resolution Gated-Ring-Oscillator-Based Vernier Time-to-Digital Converter (TDC) for low noise RF application. The TDC uses two gated ring oscillators (GRO) acting as the delay lines in an improved Vernier TDC. The already small quantization noise of the standard Vernier TDC is further first-order shaped by the GRO operation. Addition
Bug report assignment is an important part of software maintenance. In particular, incorrect assignments of bug reports to development teams can be very expensive in large software development projects. Several studies propose automating bug assignment techniques using machine learning in open source software contexts, but no study exists for large-scale proprietary projects in industry. The goal
In Space Division Multiple Access (SDMA) systems, users are separated based on their positions. The base-station (BS) signals typically reach the users through multipath clusters. The goal of this work is to find the probability that a randomly selected user will receive the signal from the BS via at least one nonshared (by any other user) multipath cluster. This probability, referred to as PSucce
Real-time applications introduce new requirements on wireless networks and impose quality thresholds on parameters like delay, jitter, throughput, and packet loss in order to run smoothly. This paper addresses this issue by presenting a MAC scheme that offers real-time applications the opportunity to reserve transmission time based on their QoS requirements for contention-free medium access. Our s
The present day global climate change is fueled by our use of fossil fuels and land use change. The already observed warming and other distinct changes in the climate system stem from these human influences and are ongoing. Due to climate system inertia, a part of the climate system's response to this historical forcing remains to manifest itself, which it will do over time. At the same time, soci
Stochastic differential equations have been shown useful in describing random continuous time processes. Biomedical experiments often imply repeated measurements on a series of experimental units and differences between units can be represented by incorporating random effects into the model. When both system noise and random effects are considered, stochastic differential mixed-effects models ensu
Modern large-scale software development is a complex undertaking and coordinating various processes is crucial to achieve efficiency. The alignment between requirements and test activities is one important aspect. Production and maintenance of software result in an ever-increasing amount of information. To be able to work efficiently under such circumstances, navigation in all available data needs
Fast correlation attacks, pioneered by Meier and Staffelbach in 1988, constitute an important class of attacks on stream ciphers. They exploit a correlation between the keystream and the output of a linear feedback shift register (LFSR) within the cipher. Several factors affect the feasibility of such an attack, e.g., the amount of available keystream and the number of taps in the LFSR. Notably, f
This paper presents an analysis on energy dissipation of digital half-band filters operating in the sub-threshold (sub-VT) region with throughput and supply voltage constraints. A 12-bit filter is implemented along with various unfolded structures, used to form a decimation filter chain. The designs are synthesized in a 65 nm low-leakage CMOS technology with various threshold voltages. A sub-VT en
This paper discusses design and measurements of a flexible Viterbi decoder fabricated in 130-nm digital CMOS. Flexibility was incorporated by providing various code rates and modulation schemes to adjust to varying channel conditions. Based on previous trade-off studies, flexible building blocks were carefully designed to cause as little area penalty as possible. The chip runs down to a minimal co
HC-128 is an eSTREAM final portfolio stream cipher. Several authors have investigated its security and, in particular, distinguishing attacks have been considered. Still, no one has been able to provide a distinguisher stronger than the one presented by Wu in the original HC-128 paper. In this paper we first argue that the keystream requirement in Wu’s original attack is underestimated by a factor
This paper presents a flow that is suitable to estimate energy dissipation of digital standard-cell based designs which are determined to be operated in the sub-threshold regime. The flow is applicable on gate-level netlists, where back-annotated toggle information is used to find the minimum energy operation point, corresponding maximum clock frequency, as well as the dissipated energy per clock
Directional antennas have been used to solve interference and connectivity issues in wireless networks for some time. Many scenarios have been presented and often positive conclusions are drawn, i.e., showing the increase in capacity. However, to date the research has mainly focused on either antenna placement or transmission scheduling but not the two combined. Such consideration will become incr
We present the concept of greedy distinguishers and show how some simple observations and the well known greedy heuristic can be combined into a very powerful strategy (the Greedy Bit Set Algorithm) for efficient and systematic construction of distinguishers and nonrandomness detectors. We show how this strategy can be applied to a large array of stream and block ciphers, and we show that our meth
