Chapter 1. Introduction
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Transcript of Chapter 1. Introduction
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Chapter 1. IntroductionHusheng LiThe University of Tennessee
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Course Contents1. Basics of communications2. Signals and noise3. Amplitude modulation4. Phase and frequency modulations5. Pulse modulation6. Analog communication system
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TextbookCommunication
Systems: An Introduction to Signals and Noise in Electrical Communication, by A. B. Carlson and P. B. Crilly, McGraw Hill, 5th edition, 2008
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LogisticsHomework: 20% (4 problems every Friday; turn
in your homework in two weeks)Midterm and final exams: 40%Quiz: 15% (will be 5 quizzes)Experiments: 25%
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Office hour and TA2:15 --- 3:15pm, MWF, MK644TA: Jingchao Bao, [email protected] website: go to my personal website http://web.eecs.utk.edu/~husheng/
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ExperimentsExperiment 1: Matlab simulation for amplitude
modulations.Experiment 2: Matlab simulation for frequency
and phase modulations.Experiment 3: USRP hardware board
experiment
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Concepts
A communication system conveys information from its source to a destination some distance away.
Some concepts: Information, analog, digital, transducer
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Elements of Communication Systems
The transmitter involves modulation and coding. The transmission channel is the medium for
communications, which could be wireless, optical or even sound.
The receiver carries out demodulation and decoding
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Negative Factors in Communications
Distortion: Waveform perturbation caused by imperfect response of the system to the desired signal itself.
Interference: Contamination by extraneous signals Noise: Random and unpredictable electrical signals.
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Fundamental LimitationsCommunications are limited by bandwidth and
noise.Bandwidth: the width of frequency band used
for the communications.Noise: The signal-to-noise ratio (SNR; S/N) is
important.When the noise is Gaussian, the channel
capacity is given by
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Modulation
Modulation involves two waveforms: a modulating signal and a carrier wave.
Modulatingsignal
AmplitudeModulation
Pulse trainWith AM
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CodingCoding is a symbol processing operation for
improved communication when the information is digital or can be approximated in the form of discrete symbols (actually there is also analog coding).
Source coding converts source information into a series of bits.
Channel coding: add redundancy to improve the robustness of transmission.
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EM Transmission
there are several effects that enable light as well as electromagnetic (EM) waves to propagate around obstructions or beyond the earth’s horizon
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Multipath and Fading
In wireless communications, the signal could be received by the receiver after reflections.
The superposition of signals from different paths could strengthen or weaken each other.
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Emerging DevelopmentsCircuit / packet switchingMultiple access: TDMA, CDMA, OFDMA.Ultra-wideband (UWB)Computer Networks: WiFi (IEEE 802.11) and
WiMAX (IEEE 802.16)Software defined radio
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Some History (1)
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Some History (2)
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Some History (3)
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Some History (4)
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Some History (5)
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Some History (6)
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AssignmentRead chapter 1