Название: Modern Digital and Analog Communication, 5th Edition Автор: B.P. Lathi, Zhi Ding
Издательство: Oxford University Press
Год: 2019
Страниц: 1025
Язык: английский
Формат: pdf (true)
Размер: 26.4 MB
As engineering students become more and more aware of the important role that communication systems play in modern society, they are increasingly motivated to learn through experimenting with solid, illustrative examples. To captivate students' attention and stimulate their imaginations, Modern Digital and Analog Communication, Fifth Edition, places strong emphasis on connecting fundamental concepts of communication theory to students' daily experiences of communication technologies. The text provides highly relevant information on the operation and features of wireless cellular systems, Wi-Fi access, broadband Internet services, and more.
The goal of this textbook is to provide the fundamental technical knowledge needed by future-generation communication engineers and technologists for designing even more efficient and more powerful communication systems of tomorrow. Critically, one major objective of this book is to answer the question: How do communication systems work? That is, how can we access information remotely using small devices such as a smartphone? Being able to answer this question is essential to designing better communication systems for the future.
One main reason for the superior quality of digital systems over analog ones is the viability of signal regeneration by repeaters and relay nodes. When directly communicating over a long distance, transmitted signals can be severely attenuated and distorted. For digital pulse signals used in digital communications, repeater nodes can be placed along the communication path at distances short enough to ensure that noise and distortion effects are minor such that digital pulses can be detected with high accuracy. At each repeater or relay node, the incoming digital pulses are detected such that new, “clean” pulses are regenerated for transmission to the next node along the path. This process prevents the accumulation of noise and distortion along the path by cleaning up the pulses at regular path intervals. We can thus transmit messages over longer distances with greater accuracy. There has been widespread application of distortionless regeneration by repeaters in long-haul communication systems or by nodes in a large (possibly heterogeneous) network. The same argument applies when making copies of digital content. In analog systems, however, signals and noise within the same bandwidth cannot be separated.
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