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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
