Rapid growth of wireless communication services in recent decades has created a huge demand of radio spectrum. Spectrum scarcity and utilization inefficiency limit the development of wireless networks. Cognitive radio is a promising tech- nology that allows secondary users to reuse the underutilized licensed spectrum of primary users. The major challenge for spectrum sharing is to achieve high spectrum efficiency while making non-intrusive access to the licensed bands. This requires in- formation of availability and quality of channel resources at secondary transmitters, however, is difficult to be obtained perfectly in practice.
標(biāo)簽： Opportunistic Spectrum Sharing
上傳時間： 2020-05-31
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In this book, we present the basic pinciples that underlie the analysis and design of digital communication system.The subject of digital communications involves the transmission of information in digital form from a source that generates the information to one or more destinations.
標(biāo)簽： J.G. Communications Proakis Digital
上傳時間： 2020-05-31
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By inventing the wireless transmitter or radio in 1897, the Italian physicist Tomaso Guglielmo Marconi added a new dimension to the world of communications. This enabled the transmission of the human voice through space without wires. For this epoch-making invention, this illustrious scientist was honored with the Nobel Prize for Physics in 1909. Even today, students of wireless or radio technology remember this distinguished physicist with reverence. A new era began in Radio Communications.
標(biāo)簽： Radio Frequency Modulation
上傳時間： 2020-06-01
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We are currently witnessing an increase in telecommunications norms and standards given the recent advances in this domain. The increasing number of normalized standards paves the way for an increase in the range of offers and services available for each consumer. Moreover, the majority of available radio frequencies have already been allocated.
標(biāo)簽： Allocation Resource Radio
上傳時間： 2020-06-01
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Mobile and wireless communication systems are a prominent communications technology of the twenty-first century with profound economic and social impacts in practically all parts of the world. The current state of wireless communication systems allows for a much wider scope of applications than what it used to be originally, that is, to be a mobile extension of the public switched telephone network.
標(biāo)簽： Allocation Resource MIMO and
上傳時間： 2020-06-01
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The ability to analyze system or circuit behavior is one of the key requirements for successful design. To put an idea to work, a designer needs both the knowledge and tools for analyzing the behavior of that new system architecture or that experi- mental circuit topology. Design decisions are grounded on the results obtained from analysis.
上傳時間： 2020-06-01
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Intensive development of digital technologies coincided in time with the beginning of the new era in telecommunications. It made possible to formalize many proce- dures of data exchange and to atomize some operations which made providing of serviceandmakeworkofmanytelecommunicationworkersmucheasier. Somenew telecommunication technologies were born out of the necessity for use of specific configurations of network elements and networks, as well as for a possibility of providing maximum characteristics of efficiency combined with high requirements to the stability of operation, the overcoming of different catastrophic situations and deadlockconditions,such as failuresand ”pending”of the networkandthe like. The thresholdbetweeninformationsystems andtelecommunicationsystems has become practically invisible. It resulted in such a new term as ”infocommunication”
標(biāo)簽： Telecommunication+Systems
上傳時間： 2020-06-01
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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(biāo)簽： Understanding_the_Basics_of_MIMO
上傳時間： 2020-06-01
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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(biāo)簽： Communication Visible Light
上傳時間： 2020-06-01
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n the first part of this book, we give an introduction to the basic applications of wireless com- munications, as well as the technical problems inherent in this communication paradigm. After a brief history of wireless, Chapter 1 describes the different types of wireless services, and works out their fundamental differences. The subsequent Section 1.3 looks at the same problem from a different angle: what data rates, ranges, etc., occur in practical systems, and especially, what combination of performance measures are demanded (e.g., what data rates need to be transmitted over short distances; what data rates are required over long distances?) Chapter 2 then describes the technical challenges of communicating without wires, putting special emphasis on fading and co-channel interference. Chapter 3 describes the most elementary problem of designing a wireless system, namely to set up a link budget in either a noise-limited or an interference-limited system. After studying this part of the book, the reader should have an overview of different types of wireless services, and understand the technical challenges involved in each of them. The solutions to those challenges are described in the later parts of this book.
標(biāo)簽： Communications Wireless Edition 2nd
上傳時間： 2020-06-01
上傳用戶：shancjb
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