Indoor wireless communications and applications

Chapter 3 addresses challenges in radio link and system design in indoor scenarios. Given the fact that most human activities take place in indoor environments, the need for supporting ubiquitous indoor data connectivity and location/tracking service becomes even more important than in the previous decades. Specific technical challenges addressed in this section are(i), modelling complex indoor radio channels for effective antenna deployment, (ii), potential of millimeter-wave (mm-wave) radios for supporting higher data rates, and (iii), feasible indoor localisation and tracking techniques, which are summarised in three dedicated sections of this chapter

Downlink channel spatial covariance estimation in realistic FDD massive MIMO systems

The knowledge of the downlink (DL) channel spatial covariance matrix at the BS is of fundamental importance for large-scale array systems operating in frequency division duplexing (FDD) mode. In particular, this knowledge plays a key role in the DL channel state information (CSI) acquisition. In the massive MIMO regime, traditional schemes based on DL pilots are severely limited by the covariance feedback and the DL training overhead. To overcome this problem, many authors have proposed to obtain an estimate of the DL spatial covariance based on uplink (UL) measurements. However, many of these approaches rely on simple channel models, and they are difficult to extend to more complex models that take into account important effects of propagation in 3D environments and of dual-polarized antenna arrays. In this study we propose a novel technique that takes into account the aforementioned effects, in compliance with the requirements of modern 4G and 5G system designs. Numerical simulations show the effectiveness of our approach.Comment: [v2] is the version accepted at GlobalSIP 2018. Only minor changes mainly in the introductio

Operating Principle and Performance Optimization of a Three-Level NPC Dual-Active-Bridge DC-DC Converter

© 1982-2012 IEEE. Aiming to improve the performance features of conventional two-level dual-active-bridge (DAB) converters, this paper presents a three-level neutral-point-clamped (NPC) DAB dc-dc converter. A general modulation pattern is initially defined, the dc-link capacitor voltage balancing is analyzed in detail, and a proper balancing control is designed. Then, a set of decoupled optimization problems is formulated as a function of the available modulation degrees of freedom to minimize the predominant converter losses. Finally, a simple and practical specific modulation strategy is provided, resembling the optimum solutions. The good performance of the proposed three-level NPC DAB converter operated with the proposed modulation strategy and voltage balancing control is verified through simulation and experiments. The capacitor voltage balancing can be guaranteed for all operating conditions. In addition, it is concluded that the multilevel topology provides benefits compared with the conventional two-level DAB converter.Postprint (published version

Parallel Evaluation of Multi-join Queries

A number of execution strategies for parallel evaluation of multi-join queries have been proposed in the literature. In this paper we give a comparative performance evaluation of four execution strategies by implementing all of them on the same parallel database system, PRISMA/DB. Experiments have been done up to 80 processors. These strategies, coming from the literature, are named: Sequential Parallel, Synchronous Execution, Segmented Right-Deep, and Full Parallel. Based on the experiments clear guidelines are given when to use which strategy. This is an extended abstract; the full paper appeared in Proc. ACM SIGMOD'94, Minneapolis, Minnesota, May 24–27, 199

Effects of Physical Characteristics of Placebos on Exercise Performance

Previous research has shown that placebos can impact medical conditions such as irritable bowel syndrome and depression as well as elicit analgesic effects and improvements in certain exercise performances. These placebo responses occur from a variety of alterations to the placebo itself or through verbal suggestion of how helpful the placebo will be. This study aimed to observe whether changing the color and quantity of capsules can induce improvements in both vertical jump and hand grip strength. This deceptive, parallel study consisted of 28 participants, with a mean age of 24.9 (±4.3) years old, that were randomly assigned to receive either two bright red and yellow capsules or a single white capsule, which all contained rice flour powder. Participants were informed that there was a 50% chance of receiving an herbal-amino acid blend or a placebo and were asked to perform two assessments of strength and neuromuscular performance. Both groups attended one session, that started with obtaining informed consent, completing a background questionnaire, performing a body composition test in the BodPod, a 5- minute seated rest with resting heart rate measured, the completion of visual analogue scales of fatigue (VAS-F) and energy (VAS-E), and a warm-up on a Monarch cycle ergometer. Participants then completed familiarization trials for both vertical jump and hand grip dynamometry using the Lode contact mat and Jamar hand dynamometer, respectively, followed by a baseline assessment for both the vertical jump and single hand grip dynamometer consisting of three attempts with 30-60 seconds of rest between attempts. Subsequently, participants received their randomized treatment along with a standardized script, which was followed by a 15-minute incubation period before repeating the VAS-F, VAS-E, and vertical jump and maximal strength tests. Before debriefing, participants were shown four images and asked to rate the perceived stimulatory properties of each on a 100-mm VAS (VAS-S); the first image was a single white capsule, the second was two red/yellow capsules, the third was two white capsules, and the fourth was a single red/yellow capsule. The primary outcome variables were assessed via mixed analysis of variance (group x time). Results suggested no significant differences between groups for any of the primary outcome variables: vertical jump, grip strength, VAS-F, VAS-E, and change of heart rate over time. However, participants perceived two red/yellow capsules (61.4±4.6) to have a greater stimulatory effect than a single white capsule (26.6±4.1) via the VAS-S (p \u3c 0.05). The results agree with previous research that individuals associate higher pill quantity and red-yellow as having stimulatory effects. That said, no effects on physical performance or perceived fatigue or energy were detected. Future research should consider using a combination of aerobic and anaerobic exercise

Automatic Parallelization of Database Queries

Although automatic parallelization of conventional language programs is now widely accepted, relatively little emphasis has been placed on automatic parallelization of database query programs (sometimes referred to as “multiple queries” ). In this paper, we discuss the unique problems associated with automatic parallelization of database programs. From this discussion, we derive a complete approach to automatic parallelization of database programs. Beside integrating a number of existing techniques, our approach relies heavily on several new concepts, including the concepts of “algorithm-level” analysis and hybrid static/dynamic scheduling

On a Class of Optimal Nonbinary Linear Unequal-Error-Protection Codes for Two Sets of Messages

Several authors have addressed the problem of designing good linear unequal error protection (LUEP) codes. However, very little is known about good nonbinary LUEP codes. We present a class of optimal nonbinary LUEP codes for two different sets of messages. By combining t-error-correcting ReedSolomon (RS) codes and shortened nonbinary Hamming codes, we obtain nonbinary LUEP codes that protect one set of messages against any t or fewer symbol errors and the remaining set of messages against any single symbol error. For t ≥ 2, we show that these codes are optimal in the sense of achieving the Hamming lower bound on the number of redundant symbols of a nonbinary LUEP code with the same parameters