-
Ultra-wideband (UWB) technology enables high data-rate short-range communica-
tion, in excess of hundredmegabit-per-secondsand up to multi-gigabit-per-seconds,
over a wide spectrum of frequencies, while keeping power consumption at low lev-
els. This low power operation results in a less-interfering co-existence with other
existed communication technologies (e.g., UNII bands).
In addition to carrying a huge amount of data over a distance of up to 230 feet
at very low power (less than 0.5mW), the UWB signal has the ability to penetrate
through the doors and other obstacles that tend to reflect signals at more limited
bandwidths and higher power densities.
標簽：
Silicon-Based
Front-Ends
RF
上傳時間：
2020-06-01
上傳用戶：shancjb
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Software Radio (SR) is one of the most important emerging technologies for the
future of wireless communication services. By moving radio functionality into
software, it promises to give flexible radio systems that are multi-service, multi-
standard, multi-band, reconfigurable and reprogrammable by software.
Today’s radios are matched to a particular class of signals that are well defined
bytheircarrierfrequencies,modulationformatsandbandwidths.Aradiotransmitter
today can only up convert signals with well-defined bandwidths over defined center
frequencies, while, on the other side of the communication chain, a radio receiver
can only down convert well-defined signal bandwidths, transmitted over specified
carrier frequencies.
標簽：
Software
Radio
上傳時間：
2020-06-01
上傳用戶：shancjb
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The serious study of the practice of how to determine the appropriate content of a
specification is a seldom-appreciated pastime. Those who have the responsibility to
design a product would prefer a greater degree of freedom than permitted by the con-
tent of a specification. Many of those who would manage those who would design
a product would prefer to allocate all of the project funding and schedule to what
they consider more productive labor. These are the attitudes, of course, that doom a
project to defeat but they are hard to counter no matter how many times repeated by
design engineers and managers. A system engineer who has survived a few of these
experiences over a long career may retire and forget the past but we have an endur-
ing obligation to work toward changing these attitudes while trying to offer younger
system engineers a pathway toward a more sure success in requirements analysis and
specification publishing.
標簽：
Requirements
Analysis
System
上傳時間：
2020-06-01
上傳用戶：shancjb
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When 3GPP started standardizing the IMS a few years ago, most analysts expected the
number of IMS deploymentsto grow dramatically as soon the initial IMS specifications were
ready (3GPP Release 5 was functionallyfrozenin the first half of 2002and completedshortly
after that). while those predictions have proven to be too aggressive owing to a number of
upheavals hitting the ICT (Information and Communications Technologies) sector, we are
now seeing more and more commercial IMS-based service offerings in the market. At the
time of writing (May 2008), there are over 30 commercial IMS networks running live traffic,
addingup to over10million IMS users aroundthe world; the IMS is beingdeployedglobally.
In addition, there are plenty of ongoing market activities; it is estimated that over 130 IMS
contracts have been awarded to all IMS manufacturers. The number of IMS users will grow
substantially as these awarded contracts are launched commercially. At the same time, the
number of IMS users in presently deployed networks is steadily increasing as new services
are introduced and operators running these networks migrate their non-IMS users to their
IMS networks.
標簽：
Multimedia
Subsystem
The
IMS
3G
IP
上傳時間：
2020-06-01
上傳用戶：shancjb
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Recent advances in wireless communication technologies have had a transforma-
tive impact on society and have directly contributed to several economic and social
aspects of daily life. Increasingly, the untethered exchange of information between
devices is becoming a prime requirement for further progress, which is placing an
ever greater demand on wireless bandwidth. The ultra wideband (UWB) system
marks a major milestone in this progress. Since 2002, when the FCC allowed the
unlicensed use of low-power, UWB radio signals in the 3.1–10.6GHz frequency
band, there has been significant synergistic advance in this technology at the cir-
cuits, architectural and communication systems levels. This technology allows for
devices to communicate wirelessly, while coexisting with other users by ensuring
that its power density is sufficiently low so that it is perceived as noise to other
users.
標簽：
Circuits
Wideband
Ultra
上傳時間：
2020-06-01
上傳用戶：shancjb
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An acronym for Multiple-In, Multiple-Out, MIMO communication sends the same data as several signals
simultaneously through multiple antennas, while still utilizing a single radio channel. This is a form of
antenna diversity, which uses multiple antennas to improve signal quality and strength of an RF link. The
data is split into multiple data streams at the transmission point and recombined on the receive side by
another MIMO radio configured with the same number of antennas. The receiver is designed to take
into account the slight time difference between receptions of each signal, any additional noise or
interference, and even lost signals.
標簽：
Understanding_the_Basics_of_MIMO
上傳時間：
2020-06-01
上傳用戶：shancjb
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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.
標簽：
Communication
Visible
Light
上傳時間：
2020-06-01
上傳用戶：shancjb
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The explosion in demand for wireless services experienced over the past 20 years
has put significant pressure on system designers to increase the capacity of the
systems being deployed. while the spectral resource is very scarce and practically
exhausted, the biggest possibilities are predicted to be in the areas of spectral reuse
by unlicensed users or in exploiting the spatial dimension of the wireless channels.
The former approach is now under intense development and is known as the cogni-
tive radio approach (Haykin 2005).
標簽：
Multi-Antenna
Wireless
Channels
Modeling
上傳時間：
2020-06-01
上傳用戶：shancjb
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In this age of science and technology, the global economy has developed so much that our
lifestyles are now extremely modernized and developed. In some ways, modern society
seems to have reached the utmost state of advancement in various areas, including eco-
nomic development, science and technology pursuit, and the utilization of the given nat-
ural environment. However, it is important to consider approaches that may allow human
beings to stay longer on the Earth while enjoying fulfilling and peaceful daily lives.
標簽：
Ecological
Networks
Design
Smart
Home
of
上傳時間：
2020-06-06
上傳用戶：shancjb
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This book is written for engineers involved in the operation, control, and
planning of electric power systems. In addition, the book provides information and
tools for researchers working in the fields of power system security and stability. The
book consists of two volumes. The first volume provides traditional techniques for the
stability analysis of large scale power systems. In addition, an overview of the main
drivers and requirements for modernization of the traditional methods for online
applications are discussed. The second volume provides techniques for online security
assessment and corrective action studies. In addition, the impact of variable generation
on the security of power systems is considered in the second volume. The first volume
may be considered as a background builder while the second volume is intended for
the coverage of edge techniques and methods for online dynamic security studies.
標簽：
Security
Dynamic
上傳時間：
2020-06-07
上傳用戶：shancjb
