In this paper we revisit hybrid analog-digital precoding systems with emphasis on their modelling and RADio-Frequency (RF) losses, to realistically evaluate their benefits in 5G system implementations. For this, we decompose the analog beamforming networks (ABFN) as a bank of commonly used RF components and formulate realistic model constraints based on their S-parameters. Specifically, we concentrate on fully-connected ABFN (FC-ABFN) and Butler networks for implementing the discrete Fourier transform (DFT) in the RF domain. The results presented in this paper reveal that the performance and energy efficiency of hybrid precoding systems are severely affected, once practical factors are considered in the overall design. In this context, we also show that Butler RF networks are capable of providing better performances than FC-ABFN for systems with a large number of RF chains.
标签： Analog-Digital Precoding Hybrid
上传时间： 2020-05-27
上传用户：shancjb
Radio frequency (RF) power amplifiers are used in everyday life for many applica- tions including cellular phones, magnetic resonance imaging, semiconductor wafer processing for chip manufacturing, etc. Therefore, the design and performance of RF amplifiers carry great importance for the proper functionality of these devices. Furthermore, several industrial and military applications require low-profile yet high-powered and efficient power amplifiers.
标签： Introduction Amplifier Design Power to RF
上传时间： 2020-05-27
上传用户：shancjb
With the rapid expansion of wireless consumer products,there has been a con- siderable increase in the need for RADio-Frequency (RF) planning, link plan- ning, and propagation modeling.A network designer with no RF background may find himself/herself designing a wireless network. A wide array of RF planning software packages can provide some support, but there is no substi- tute for a fundamental understanding of the propagation process and the lim- itations of the models employed. Blind use of computer-aided design (CAD) programs with no understanding of the physical fundamentals underlying the process can be a recipe for disaster. Having witnessed the results of this approach, I hope to spare others this frustration.
标签： Introduction Propagation to RF
上传时间： 2020-05-27
上传用户：shancjb
Thanks for purchasing the RFI Pocket Guide. The purpose of this guide to help you identify, locate and resolve radio frequency interference (RFI). It includes some basic theory and measurement techniques and there are a number of handy references, tables, and equations that you may find useful. The focus is to assist both amateur radio operators, as well as commercial broadcast and communications engineers, in resolving a variety of common interference issues.
标签： Radio_Frequency_Interference_Pock et_Guide
上传时间： 2020-06-01
上传用户：shancjb
The unguided transmission of information using electromagnetic waves at radio frequency (RF) is often referred to as wireless communications, the first demonstration of which took place at the end of the 19th cen- tury and is attributed to Hertz. The technology was, shortly thereafter, commercialised by, amongst others, Marconi in one of the first wire- less communication systems, i.e., wireless telegraphy. In the first half of the 20th century the technology was developed further to enable more than the mere transmission of Morse code. This first resulted in uni- directional radio broadcasting and several years later also in television broadcasting.
标签： Imperfections RF
上传时间： 2020-06-01
上传用户：shancjb
Radio frequency spectrum is a scarce and critical natural resource that is utilized for many services including surveillance, navigation, communication, and broadcast- ing. Recent years have seen tremendous growth in the use of spectrum especially by commercial cellular operators. Ubiquitous use of smartphones and tablets is one of the reasons behind an all-time high utilization of spectrum. As a result, cellular operators are experiencing a shortage of radio spectrum to meet bandwidth demands of users. On the other hand, spectrum measurements have shown that much spectrum not held by cellular operators is underutilized even in dense urban areas. This has motivated shared access to spectrum by secondary systems with no or minimal impact on incumbent systems. Spectrum sharing is a promising approach to solve the problem of spectrum congestion as it allows cellular operators access to more spectrum in order to satisfy the ever-growing bandwidth demands of commercial users.
标签： Spectrum Sharing Between Radars
上传时间： 2020-06-01
上传用户：shancjb
Visible light communications (VLC) is the name given to an optical wireless communication system that carries information by modulating light in the visible spectrum (400–700 nm) that is principally used for illumination [1–3]. The communications signal is encoded on top of the illumination light. Interest in VLC has grown rapidly with the growth of high power light emitting diodes (LEDs) in the visible spectrum. The motivation to use the illumination light for communication is to save energy by exploiting the illumination to carry information and, at the same time, to use technology that is “green” in comparison to radio frequency (RF) technology, while using the existing infrastructure of the lighting system.
标签： Communication Visible Light
上传时间： 2020-06-01
上传用户：shancjb
Although the origins of radio frequency based wireless networking can be traced back to the University of Hawaii’s ALOHANET research project in the 1970s, the key events that led to wireless networking becoming one of the fastest growing technologies of the early 21st century have been the ratification of the IEEE 802.11 standard in 1997, and the subsequent development of interoperability certification by the Wi-Fi Alliance (formerly WECA).
标签： Networking Technology Wireless
上传时间： 2020-06-01
上传用户：shancjb
The phenomenon of electrostatic discharge (ESD) has been known for a long time, but recently a growing interest has been observed in ESD in radio frequency (RF) technology and ESD issues in RF applications.
标签： Technology Circuits ESD and RF
上传时间： 2020-06-05
上传用户：shancjb
Introduction to Radio Frequency Identification (RFID): RFID is a wireless modulation and demodulation technique for automatic identification of objects, tracking goods, smart logistics, and access con- trol. RFID is a contactless, usually short‐distance transmission and reception technique for unique ID data transfer from a tagged object to an interrogator (reader). The generic configuration of an RFID system comprises (i) an ID data‐carrying tag, (ii) a reader, (iii) a middleware, and (iv) an enterprise application.
标签： Chipless_Radio_Frequency_Identifi cation
上传时间： 2020-06-08
上传用户：shancjb
