The goal of this book is to provide a concise but lucid explanation and deriva- tion of the fundamentals of spread-spectrum communication systems. Although spread-spectrum communication is a staple topic in textbooks on digital com- munication, its treatment is usually cursory, and the subject warrants a more intensive exposition. Originally adopted in military networks as a meanS of ensuring secure communication when confronted with the threats of jamming and interception, spread-spectrum systems are now the core of commercial ap- plications such as mobile cellular and satellite communication.
标签： Principles Spectrum Spread of
上传时间： 2020-05-31
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Wireless meanS different things to different people. For this book, it refers to the radio systems that provide point-to-point, point-to-multipoint, and Earth-space communications over transmission links that propagate outside buildings through the lower atmosphere. Wireless systems are being built that provide data transmission between computers and other devices on one’s own desk. These are part of the wireless world but not the part where, except for interference perhaps, the atmosphere has any influence. The intent of this book is to provide a description of the physical phenomena that can affect propagation through the atmosphere, present sample measurements and statistics, and provide models that system designers can use to calculate their link budgets and estimate the limitations the atmosphere may place on their design.
标签： Communication Propagation Handbook Wireless for
上传时间： 2020-05-31
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Soon after Samuel Morse’s telegraphing device led to a deployed electri- cal telecommunications system in 1843, waiting lines began to form by those wanting to use the system. At this writing queueing is still a significant factor in designing and operating communications services, whether they are provided over the Internet or by other meanS, such as circuit switched networks.
标签： Telecommunication Queueing Packet Theory with
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This paper presents a Hidden Markov Model (HMM)-based speech enhancement method, aiming at reducing non-stationary noise from speech signals. The system is based on the assumption that the speech and the noise are additive and uncorrelated. Cepstral features are used to extract statistical information from both the speech and the noise. A-priori statistical information is collected from long training sequences into ergodic hidden Markov models. Given the ergodic models for the speech and the noise, a compensated speech-noise model is created by meanS of parallel model combination, using a log-normal approximation. During the compensation, the mean of every mixture in the speech and noise model is stored. The stored meanS are then used in the enhancement process to create the most likely speech and noise power spectral distributions using the forward algorithm combined with mixture probability. The distributions are used to generate a Wiener filter for every observation. The paper includes a performance evaluation of the speech enhancer for stationary as well as non-stationary noise environment.
标签： Telecommunications Processing Signal for
上传时间： 2020-06-01
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The goal of this book is to provide a concise but lucid explanation and deriva- tion of the fundamentals of spread-spectrum communication systems. Although spread-spectrum communication is a staple topic in textbooks on digital com- munication, its treatment is usually cursory, and the subject warrants a more intensive exposition. Originally adopted in military networks as a meanS of ensuring secure communication when confronted with the threats of jamming and interception, spread-spectrum systems are now the core of commercial ap- plications such as mobile cellular and satellite communication.
标签： Spread-Spectrum Communication Systems 1st
上传时间： 2020-06-01
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Having dealt with in-depth analysis of SS#7, GSM and GPRS networks I started to monitor UTRAN interfaces approximately four years ago. Monitoring interfaces meanS decoding the data captured on the links and analysing how the different data segments and messages are related to each other. In general I wanted to trace all messages belonging to a single call to prove if the network elements and protocol entities involved worked fine or if there had been failures or if any kind of suspicious events had influenced the normal call proceeding or the call’s quality of service. Cases showing normal network behaviour have been documented in Kreher and Ruedebusch (UMTS Signaling. John Wiley & Sons, Ltd, 2005), which provides examples for technical experts investigating call flows and network procedures.
标签： Performance Measurement Practical Guide UMTS
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Telecommunications is today widely understood to mean the electrical meanS of communicating over a distance. The first form of telecommunications was that of the Telegraph, which was invented quite independently in 1837 by two scientists, Wheatstone and Morse. Telegraphy was on a point-to-point unidirectional basis and relied on trained operators to interpret between the spoken or written word and the special signals sent over the telegraph wire. However, the use of telegraphy did greatly enhance the operations of railways and, of course, the dissemination of news and personal messages between towns.
标签： Telecommunications Understanding Networks
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Wavelength division multiplexing (WDM) refers to a multiplexing and transmission scheme in optical telecommunications fibers where different wavelengths, typically emitted by several lasers, are modulated independently (i.e., they carry independent information from the transmitters to the receivers). These wavelengths are then multiplexed in the transmitter by meanS of passive WDM filters, and likewise they are separated or demultiplexed in the receiver by meanS of the same filters or coherent detection that usually involves a tunable local oscillator (laser).
标签： Multiplexing Wavelength Division
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This is a book on wireless communication. That usually meanS communica- tion by radio, though ultrasound and infrared light are also used occasion- ally. The term “wireless” has come to mean nonbroadcast communication, usually between individuals who very often use portable or mobile equip- ment. The term is rather vague, of course, and there are certainly borderline applications that are called wireless without falling exactly into the above definition.
标签： Communication Technology Wireless
上传时间： 2020-06-01
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Static electricity is the most ancient form of electricity known to humans. More than 2000 years ago, the Greeks recognized the attraction between certain mate- rials when they were rubbed together; indeed, the word electricity comes from the Greek elektron, which meanS amber. During the seventeenth and eighteenth centuries, several key experiments were conducted to understand and measure static electricity. But the discovery of electromagnetism and its formidable break- through has rapidly outgrown interest in static electricity. Even today, where the industrial applications of static electricity are not insignificant, they cannot compare with those of electromagnetism and electrodynamics.
标签： Understand Discharge Electro Static
上传时间： 2020-06-05
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