Silicon technology continues to progress, but device scaling is rapidly
taking the metal oxide semiconductor field-effect transistor (MOSFET) to its
limit. When MOS technology was developed in the 1960's, channel lengths
were about 10 micrometers, but researchers are now building transistors with
channel lengths of less than 10 nanometers. New kinds of transistors and
other devices are also being explored. Nanoscale MOSFET engineering
continues, however, to be dominated by concepts and approaches originally
developed to treat microscale devices...
The efficient management and sharing of the spectrum among the users is an important issue, frequency channels have to be reused as much as possible in order to support the many thousands of simultaneous call in any typical of mobile system. In cellular architecture, cell is serviced by a base station located at its center. A number of cells are linked to a mobile switching center which also acts as a gateway of the cellular network to
Our first chapter puts LTE into its historical context, and lays out its requirements and key
technical features. We begin by reviewing the architectures of UMTS and GSM, and
by introducing some of the terminology that the two systems use. We then summarize
the history of mobile telecommunication systems, discuss the issues that have driven the
development of LTE, and show how UMTS has evolved first into LTE and then into an
enhanced version known as LTE-Advanced. The chapter closes by reviewing the standardization
process for LTE....
The third generation (3G) mobile communication system is the next big thing in the world of mobile telecommunications. The first generation included analog mobile phones [e.g., Total Access Communications Systems (TACS), Nordic Mobile Telephone (NMT), and Advanced Mobile Phone Service (AMPS)], and the second generation (2G) included digital mobile phones [e.g., global system for mobile communications (GSM), personal digital cellular (PDC), and digital AMPS (D-AMPS)].
Multi-carrier modulation, in particular Orthogonal Frequency Division
Multiplexing (OFDM), has been successfully applied to a wide variety of
digital communications applications over the past several years. Although
OFDM has been chosen as the physical layer standard for a diversity of
important systems, the theory, algorithms, and implementation techniques
remain subjects of current interest. This is clear from the high volume of
papers appearing in technical journals and conferences.
This is an undergraduate course in digital communications, which is designed to prepare students for engineering work in high-tech industries and for graduate work in communications, signal processing, and computer systems. The course covers basic concepts and useful tools for design and performance analysis of transmitters and receivers in the physical layer of a communication system. Prerequisite: An introductory course in probability. A course in signals and systems. Texts: J.G. Proakis, M. Salehi, Communication Systems Engineering M. P. Fitz, A Course in Communication Theory Graders:...
This book follows from my first edition and is intended to provide a thorough,
up to date, treatment of wireless physical communications. The book is
derived from a compilation of course material that I have taught in a graduatelevel
course on physical wireless communications at Georgia Tech over the past
decade. This textbook differs from others on the subject by stressing mathematical
modeling and analysis. My approach is to include detailed derivations
from first principles.
UMTS standard: WCDMA/FDD Layer 1
17.1 TRANSPORT CHANNELS AND PHYSICAL CHANNELS (FDD)
17.1.1 Transport channels In the terminology used in wireless communications, ‘transport channels’ are the services offered by Layer 1 to the higher layers. The purpose of this section is to introduce basic terminology and abbreviations used in practice. For more details, see www.3gpp.org. We start with the deﬁnition of the channels.
PACKET ACCESS IN UTRA FDD AND UTRA TDD
In this chapter, ﬁrst a brief introduction to UMTS Terrestrial Radio Access (UTRA) matters is provided, such as fundamental radio access network concepts, basics of, for example, the physical and the MAC layer, and the types of channels deﬁned (namely logical, transport and physical channels). This is followed by a discussion of certain UTRA FDD features, such as soft handover, fast power control and compressed mode operation.
Knowledge of the Earth’s structure and dynamics calls for a multi-disciplinary study that
makes use of the most advanced methods of Physics, Chemistry, Geology, Mathematics
and Information Technology, in the framework, or in close collaboration with, the
different branches of Earth Sciences such as Geology, Geophysics and Geodesy.
Grid research, rooted in distributed and high performance computing, started in midto-
late 1990s when scientists around the world acknowledged the need to establish an
infrastructure to support their collaborative research on compute and data intensive
experiments. Soon afterwards, national and international research and development
authorities realized the importance of the Grid and gave it a primary position on their
research and development agenda.
So far we have only considered single-input multi-output
(SIMO) and multi-input single-output (MISO) channels. They provide diversity and power gains but no degree-offreedom
(d.o.f.) gain. D.o.f gain is most useful in the high SNR regime. MIMO channels have a potential to provide d.o.f gain. We would like to understand how the d.o.f gain depends
on the physical environment and come up with statistical
models that capture the properties succinctly.
Today, the data acquisition technology has found its way into virtually every segment
of electronics. A digital signal processing (DSP) system accepts analog signals as input,
converts those analog signals to numbers, performs computations using the numbers
and eventually converts the results of the computations back into analog signals. Once
converted to numbers, signals are unconditionally stable. Error detection and
correction methods can be applied to store,transmit and reproduce numbers with no
corruption. Signals stored digitally are really just large arrays of numbers.
Orthogonal frequency division multiplexing (OFDM) is becoming the chosen
modulation technique for wireless communications. OFDM can provide large data
rates with sufficient robustness to radio channel impairments. Many research centers
in the world have specialized teams working in the optimization of OFDM for
countless applications. Here, at the Georgia Institute of Technology, one of such
teams is in Dr. M. A. Ingram’s Smart Antenna Research Laboratory (SARL), a part
of the Georgia Center for Advanced Telecommunications Technology (GCATT).
Search of accessible beams for monitoring in a reception poin. Reception and processing physical channels in directions "subscriber-satellite" and "satellite-subscriber".
Primary processing of the received digital signal (extraction of data
packages, demultiplexing, removal of scrambler, deinterleaving,removal convolutional codings).
The demand of transmission of images and video is increasing quickly recently and researchers are trying to invest good solutions to improve the quality of these over wireless networks. There are still challenges due to the different characteristics and quality of images between wired and wireless channels. An important issue is congestion control to ensure network stability and achieve a reasonably fair distribution of the network resources among the users.
–Resemblance between the source and recipient of the message
–Knowledge of the source through repeated or prolonged exposure
–Affection for the source resulting from physical appearance, behavior, or other personal traits