chapter 1. introduction husheng li the university of tennessee
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Chapter 1. IntroductionHusheng LiThe University of Tennessee
Course Contents1. Basics of communications
2. Signals and noise
3. Amplitude modulation
4. Phase and frequency modulations
5. Pulse modulation
6. Analog communication system
TextbookCommunication
Systems: An Introduction to Signals and Noise in Electrical Communication, by A. B. Carlson and P. B. Crilly, McGraw Hill, 5th edition, 2008
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%
Office hour and TA2:15 --- 3:15pm, MWF, MK644
TA: Jingchao Bao, [email protected]
Course website: go to my personal website
http://web.eecs.utk.edu/~husheng/
ExperimentsExperiment 1: Matlab simulation for amplitude
modulations.
Experiment 2: Matlab simulation for frequency and phase modulations.
Experiment 3: USRP hardware board experiment
Concepts
A communication system conveys information from its source to a destination some distance away.
Some concepts: Information, analog, digital, transducer
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
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.
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
Modulation
Modulation involves two waveforms: a modulating signal and a carrier wave.
Modulatingsignal
AmplitudeModulation
Pulse trainWith AM
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.
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
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.
Emerging DevelopmentsCircuit / packet switching
Multiple access: TDMA, CDMA, OFDMA.
Ultra-wideband (UWB)
Computer Networks: WiFi (IEEE 802.11) and WiMAX (IEEE 802.16)
Software defined radio
Some History (1)
Some History (2)
Some History (3)
Some History (4)
Some History (5)
Some History (6)
AssignmentRead chapter 1