There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

The use of flying platforms such as unmanned aerial vehicles (UAVs), popularly known as drones, is rapidly growing. In particular, with their inherent attributes such as mobility, flexibility, and adaptive altitude, UAVs admit several key potential applications in wireless systems. On the one hand, UAVs can be used as aerial base stations to enhance coverage, capacity, reliability, and energy efficiency of wireless networks. On the other hand, UAVs can operate as flying mobile terminals within a cellular network. Such cellular-connected UAVs can enable several applications ranging from real-time video streaming to item delivery. In this paper, a comprehensive tutorial on the potential benefits and applications of UAVs in wireless communications is presented. Moreover, the important challenges and the fundamental tradeoffs in UAV-enabled wireless networks are thoroughly investigated. In particular, the key UAV challenges such as 3D deployment, performance analysis, channel modeling, and energy efficiency are explored along with representative results. Then, open problems and potential research directions pertaining to UAV communications are introduced. Finally, various analytical frameworks and mathematical tools, such as optimization theory, machine learning, stochastic geometry, transport theory, and game theory are described. The use of such tools for addressing unique UAV problems is also presented. In a nutshell, this tutorial provides key guidelines on how to analyze, optimize, and design UAV-based wireless communication systems.

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A Tutorial on UAVs for Wireless Networks: Applications, Challenges, and Open Problems

The use of flying platforms such as unmanned aerial vehicles (UAVs), popularly known as drones, is rapidly growing. In particular, with their inherent attributes such as mobility, flexibility, and adaptive altitude, UAVs admit several key potential applications in wireless systems. On the one hand, UAVs can be used as aerial base stations to enhance coverage, capacity, reliability, and energy efficiency of wireless networks. On the other hand, UAVs can operate as flying mobile terminals within a cellular network. Such cellular-connected UAVs can enable several applications ranging from real-time video streaming to item delivery. In this paper, a comprehensive tutorial on the potential benefits and applications of UAVs in wireless communications is presented. Moreover, the important challenges and the fundamental tradeoffs in UAV-enabled wireless networks are thoroughly investigated. In particular, the key UAV challenges such as three-dimensional deployment, performance analysis, channel modeling, and energy efficiency are explored along with representative results. Then, open problems and potential research directions pertaining to UAV communications are introduced. Finally, various analytical frameworks and mathematical tools such as optimization theory, machine learning, stochastic geometry, transport theory, and game theory are described. The use of such tools for addressing unique UAV problems is also presented. In a nutshell, this tutorial provides key guidelines on how to analyze, optimize, and design UAV-based wireless communication systems.

A system is provided for locating a vehicle. The system comprises a transmission device such as a key fob for transmission and receiving of a signal. Typically the key fob has a plurality of indicators such as LED indicators arranged in a circle. The key fob is adapted to transmit a radio frequency or microwave frequency transmission signal. An antenna array is positioned on or in a vehicle. The array comprises a plurality of antennas, generally arranged in a circular pattern. The array is adapted to receive the transmission signal from the transmission device which is converted to be analyzed by a microcontroller unit (MCU). The MCU is adapted to: (i) receive digital data converted from the transmission signal, (ii) calculate an angle of arrival (AOA) or direction of arrival (DOA) based on known components and an algorithm, and (iii) transmit a selection signal back to the key fob. A signal processing unit is coupled to the plurality of antennas and the MCU. The signal processing unit is adapted to receive the signal transmission from each antenna, convert the signal to digital data, and transmit the digital data to the MCU.

Automotive direction finding system based on received power levels

Multiple-input-multiple-output (MIMO) antenna systems are a key enabling technology for modern fourth-generation (4G) wireless systems. The need for higher data rates for multimedia applications within the limited bandwidth and power levels led the way to the use of multiple antennas at the receiver and transmitter ends. Printed MIMO antenna systems, supporting multiple bands, including the lower band of the 4G wireless standard (LTE), pose a challenge in terms of available size. In this work, we start by defi ning the new required metrics to characterize MIMO antenna systems. We then present several recent printed multi-band MIMO antenna systems, along with some isolation-enhancement mechanisms that are used in these closely packed antennas.

Printed Multi-Band MIMO Antenna Systems and Their Performance Metrics

Multiple-input-multiple-output (MIMO) antenna systems are a key enabling technology for modern fourth-generation (4G) wireless systems. The need for higher data rates for multimedia applications within the limited bandwidth and power levels led the way to the use of multiple antennas at the receiver and transmitter ends. Printed MIMO antenna systems, supporting multiple bands, including the lower band of the 4G wireless standard (LTE), pose a challenge in terms of available size. In this work, we start by defining the new required metrics to characterize MIMO antenna systems. We then present several recent printed multi-band MIMO antenna systems, along with some isolation-enhancement mechanisms that are used in these closely packed antennas.

Printed Multi-Band MIMO Antenna Systems and Their Performance Metrics [Wireless Corner]

In the past six years or so, the number of scientific articles and conference papers providing possible multiple-input, multiple-output (MIMO) antenna system solutions has noticeably increased. Flagship conferences on antennas and propagation have recently had multiple sessions addressing MIMO antenna systems and their applications. The importance of such antenna systems lies in the magnitude of their application in current wireless devices and gadgets, and this thrust will continue because fourth-generation (4G) and the upcoming fifth-generation (5G) wireless standards rely heavily on MIMO technology. But throughout the years, and up until now, a wide range of publications still suffer from some major misconceptions and unclear understanding of the fundamental aspects while designing, characterizing, and evaluating such multiantenna systems.

Current Misuses and Future Prospects for Printed Multiple-Input, Multiple-Output Antenna Systems [Wireless Corner]

In this paper, a step-by-step procedure is devised for extracting the material parameters to facilitate and simplify the design procedure of metamaterial structures using commercial software packages. A parameter-retrieval method using the S parameters is used to calculate the curves for the complex permittivity and permeability of the metamaterial based on its unit element. The S parameters are extracted using HFSSTM, which is a Finite-Element-Method (FEM)-based full-wave simulator. The permittivity and permeability curves are calculated using a MATLAB script. Two different methods are used in HFSS to extract the S parameters: one using perfect electric and perfect magnetic (PE-PM) boundary conditions, and the second using the master-slave boundary conditions. Wave ports and Floquet ports are used to excite the structure. The results of the proposed procedure are validated by comparing the calculated curves with already published results.

Mohammad S. Sharawi

Papers

Automotive direction finding system based on received power levels

Printed Multi-Band MIMO Antenna Systems and Their Performance Metrics

Printed Multi-Band MIMO Antenna Systems and Their Performance Metrics [Wireless Corner]

Current Misuses and Future Prospects for Printed Multiple-Input, Multiple-Output Antenna Systems [Wireless Corner]

Extraction of Material Parameters for Metamaterials Using a Full-Wave Simulator [Education Column]