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Multi-user MIMO offers big advantages over conventional point-to-point MIMO: it works with cheap single-antenna terminals, a rich scattering environment is not required, and resource allocation is simplified because every active terminal utilizes all of the time-frequency bins. However, multi-user MIMO, as originally envisioned, with roughly equal numbers of service antennas and terminals and freq
The cluster power is an important parameter for cluster-based wireless channel models. This paper addresses modeling and estimation of the cluster power for wireless channels. A novel way of estimating the cluster decay and cluster fading, where the effects of the noise floor is taken into account, is presented. Due to the noise floor present in the measurement, only a limited number of clusters a
This paper presents the results of an empirical study of wireless propagation channels for vehicle-to-vehicle communications in street intersections, a scenario especially important for collision avoidance applications. The results are derived from a channel measurement campaign performed at 5.6 GHz in four different types of urban intersections. We present results on typical power delay profiles,
Background: Spot pricing is considered as a significant supplement for building a full-fledged market economy for the Cloud ecosystem. However, it seems that both providers and consumers are still hesitating to enter the Cloud spot market. The relevant academic community also has conflicting opinions about Cloud spot pricing in terms of revenue generation. Aim: This work aims to systematically ide
This paper proposes two low-complexity two-dimensional channel estimators for MIMO-OFDM systems derived from a joint time–frequency channel estimator. The estimators exploit both time and frequency correlations of the wireless channel via use of Slepian-basis expansions. The computational saving comes from replacing a two-dimensional Slepian-basis expansion with two serially concatenated one-dimen
The learning parity with noise (LPN) problem has recently proved to be of great importance in cryptology. A special and very useful case is the Ring-LPN problem, which typically provides improved efficiency in the constructed cryptographic primitive. We present a new algorithm for solving the Ring-LPN problem in the case when the polynomial used is reducible. It greatly outperforms the previous al
Multi-site multi-antenna measurements for semiurban microcell environment at 2.6 GHz are performed with four base stations (BSs) and one mobile station (MS). Three BSs are provided with four antenna elements in closely spaced copolarized configuration, and one BS is provided with a single antenna element. The MS is equipped with a cylindrical uniform array consisting of 64 dual-polarized antenna e
Abstract in UndeterminedMultiple-antenna handheld terminals are an integral part of the latest mobile communication systems, due to the adoption of multiple-input multiple-output (MIMO) technology. In this contribution, MIMO performances of three multiple-antenna configurations for smart phones are investigated in an urban macrocellular environment, based on an extensive MIMO measurement campaign
Context: Test driven development (TDD) has been extensively researched and compared to traditional approaches (test last development, TLD). Existing literature reviews show varying results for TDD. Objective: This study investigates how the conclusions of existing literature reviews change when taking two study quality dimension into account, namely rigor and relevance. Method: In this study a sys
Abstract in UndeterminedInside a tunnel, electromagnetic wave propagation differs strongly from the well understood "open-air" situation. The characterization of the tunnel environment is crucial for deploying vehicular communication systems. In this paper we evaluate vehicle-to-vehicle (V2V) radio channel measurements inside a tunnel. We estimate the time-varying root mean square (rms) delay and
Abstract in UndeterminedThis paper presents a filtering ADC for the LTE communication standard, where a second-order Delta-Sigma modulator (DSM) is incorporated into the third-order Chebychev channel-select filter (CSF) of the radio receiver. The CSF introduces an additional third-order suppression of both thermal and quantization DSM noise, while the CSF transfer function is maintained. A design
An all digital phase-locked loop (ADPLL) has been implemented in a 90-nm CMOS process. It uses a phase-frequency detector (PFD) connected to two time-to-digital converters (TDC). To save power the TDCs use delay line cells with uneven delay time. During frequency acquisition an automatic tuning bank controller selects active bank of the digitally controlled oscillator (DCO), which features three s
MIMO systems ideally achieve linear capacity gain proportional to the number of antennas. However, the compactness of terminal devices limits the number of spatial degrees of freedom (DOFs) in such systems, which motivates efficientantenna design techniques to exploit all available DOFs. In this contribution, we present a compact six-port dielectric resonator antenna (DRA) array which utilizes spa
Open source software has been gaining popularity, especially among commercial organizations. The broad industry acceptance is in large part due to the demonstrated ability of open source solutions to compete with proprietary alternatives. Using open source software components enables companies to reduce their own development costs, and thus improve software development efficiency. Many open source
In this paper, we propose a directed and weighted graph model for describing P2P networks using BitTorrent protocol. Then, we analysis the topological properties of the model based on complex networks theory. We find that the node strength follows a power-law distribution and that there exists a positive correlation between flow betweenness and out-strength. We also include some other findings abo
This paper presents a 2.45 GHz wake-up receiver front-end intended for use in sensor networks, and is designed to receive data modulated with on-off-keying. Manufactured in 65 nm CMOS it employs an uncertain IF structure with three phase passive mixer and high gain amplifier chain. With the modulation frequency response tailored to the detector behaviour, it achieves a sensitivity of -88 dBm at BE
Context: The questions of how many individuals and how much time to use for a single testing task are critical in software verification and validation. In software review and usability evaluation contexts, positive effects of using multiple individuals for a task have been found, but software testing has not been studied from this viewpoint. Objective: We study how adding individuals and imposing
