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We derive the interarrival distribution of a workload input process which is a variation of the infinite source Poisson process for packet traffic. It accounts for long-range dependence and self-similarity exhibited by real traces in the Internet. The packet generation process is compound Poisson over each session which has a heavy tailed distribution. Considering the dependence induced by the wor
It is well known that user proximity introduces absorption and impedance mismatch losses that severely degrade multiple-input multiple-output (MIMO) performance of handset antennas. In this work, we experimentally verified the potential of adaptive impedance matching (AIM) to mitigate user interaction effects and identified the main AIM gain mechanism in realistic systems. A practical setup includ
It is well known that fast correlation attacks can be very efficient if the feedback polynomial is of low weight. These feedback polynomials can be considered weak in the context of stream ciphers. This paper generalizes the class of weak feedback polynomials into polynomials were taps are located in several groups, possibly far apart. Low weight feedback polynomials are thus a special case of thi
Two gated ring oscillators (GROs) act as the delay lines in an improved Vernier time-to-digital converter (TDC), where the already small quantization noise of the standard Vernier TDC is further first-order shaped by the GRO operation. The TDC has been implemented in a 90nm CMOS process and consumes 3mA from 1.2V when operating at 25MHz. The native Vernier resolution of the TDC is 5.8ps, while the
Optimization techniques always play an important role in designing high-performance wireless systems. This presented thesis studies a selected set of optimization problems for different kinds of wireless networks, making use of mathematical programming techniques to find optimal solutions and of efficient heuristics to find near-optimal solutions. The basic contribution of the thesis consists in a
Excitation of the chassis enables single-antenna terminals to achieve good bandwidth and radiation performance, due to the entire chassis being utilized as the main radiator. In contrast, the same chassis excitation phenomenon complicates the design of multiple antennas for MIMO applications, since the same characteristic mode of the chassis may be effectively excited by more than one antenna, lea
Given a weighted directed graph where some arcs can fail while others are reliable, we aim to compute a shortest pair of failure-disjoint paths. If a reliable arc is used by both paths, its cost is counted only once. We present a polynomial time algorithm to solve the problem.
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
The 60 GHz band is very promising for high data rate (>1 Gb/s) wireless systems operating at short ranges. However, due to the short wavelengths in this frequency band, the shadowing effects cuased by human bodies and furniture are severe and need to be modeled properly. In this paper, we present an experimental, measurement-based characterization of the reflection and shadowing effects in the 60
Test-Driven Development (TDD) is a software development approach where test cases are written before actual development of the code in iterative cycles. Context: TDD has gained attention of many software practitioners during the last decade since it has contributed several benefits to the software development process. However, empirical evidence of its dominance in terms of internal code quality,
At the same time as our dependence on IT systems increases, the number of reports of problems caused by failures of critical IT systems has also increased. Today almost every system or service, e.g., water, power supply, transportation, is dependent on IT systems, and failure of these systems has serious and negative effects on society. In general, governmental organizations are responsible for de
In this paper we present the implementation of a WebRTC gateway service that can forward ad-hoc RTP data plane traffic from a browser inside a local hospital network to a browser on a local home network. The gateway leverages the same infrastructure used by the hospital to tunnel sensor and control data for medical devices in home-care deployments. In our use case, doctors at hospitals can only ac
