ECE 4710 / 7710 Communication Systems Goal : To provide an introduction to digital ccommunication ommunication system basics. Topics include: signal analysis, power spectrum density, baseband digital signaling, signal transmission and filtering, modulated digital communications, error performance, and communication link analysis. Instructor : Dr. Curt Davis Office : 323 EBW Phone: 884-3789 Email: DavisCH@m
[email protected] issouri.edu Course Time : M W F from 10-11 pm Course Location : 355 EBW Course Eligibility : Undergraduate Students: satisfactory completion of ECE 3810. Graduate Students: basic knowledge of probability and linear signals and systems. Text : Digital & Analog Communication Systems – 7 th Edition, Leon Couch, Prentice Hall, 2007.
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ECE 4710 / 7710 Communication Systems Homework : Homework will be assigned approximately once a week and will be due at the beginning of the hour for the class class period one week later. later. Each student is allowed to turn turn in one late homework assignment at 50% credit and this must be turned in no later than 3 PM on the day after the assignment is due. After this no credit will be given for late homewor homework. k. If you plan to miss a class for any reason, you are responsible for arranging for the homework to be turned in. Exams : All exams ar aree mandatory mandatory.. Failure to ta take ke an exam will result in an F for that exam. If for some legitimate reason (sickness, death in the family, etc.) you cannot take an exam on the scheduled day, you must notify me prior to the exam so other arrangements can be made. Grading : The following perc percentages entages will be used to determ determine ine your final course gr grade: ade:
Homework First Exam Second Exam Final Exam
15% 25% 30% 30%
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ECE 4710 / 7710 Communication Systems Grading Scale** :
Grade A B C D F
% > 90 80-89 70-79 60-69 < 60
** Grading scale may be adjusted at the end of the semester depending upon class performance and overall distribution of final %’s. Different grading scales may be used for undergraduate and graduate students based upon class performance. Normally Normally there is no “curve” for graduate students final grading scale. Academic Dishonesty : Academic honesty is fundamental to the activities and principles principles of a university university.. All members of the academic community must be confident that each person’s work has been responsibly and
honorably acquired,ordeveloped, and to gain an advantage not academic given to all students as dishonest whether not the effor effort t ispresented. successful.Any Theeffort academic community re regards gards dishonesty aiss an extremely serious matter, matter, with serious consequences that range from proba probation tion to expulsion. When in doubt about plagiarism, paraphrasing, quoting, or collaboration, consult the course instructor. Copying homework assignments (from previous solutions or other people) and cheating on exams will not be tolerated. Any occurrence of this will be deal dealtt with on a case by case basis and may be grounds for dismissal from the class.
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ECE 4710 / 7710 Communication Systems Electronic Notes A complete set of course notes are available in MS PowerPoint format for the use of the student. The notes ar aree organized by lecture and closely follow th thee lecture #’s #’s identified in the course outline. All 41 lectures are currently aavailable vailable on the website. These are being provided because this course covers a great deal of material in a short time. Past experience has shown that it is difficult for students to take all the notes and concentrate on the lecture content at the same time. Thus, students are en encouraged couraged to get the the lecture notes prior to coming to class. These should then then be broug brought ht to class sso o that additional comments can be added added to the n notes otes as needed. In addition, the students are encouraged encouraged to bring their course textbook to every class so that they can easily refer to figures and tables that are referenced by the instructor frequently. A complete set of the homework assignments in MS Word format are also being provided for easy access. The lecture notes and homework assignments are available at http://bengal.missouri.edu/~davisch/ece4710/
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ECE 4710 / 7710 Communication Systems Computer Useage Homework assignments will often require you to use a computer to plot signals, compute spectral responses, evaluate integrals, generate random numbers for probability calculations, and analyze communication communication systems. I strongl strongly y encourage students in this course to use either Matlab or Mathcad for homework problems that require this type of analysis. Student versions versions of these software programs are available at very reaso reasonable nable prices. Computer Spectrum in Brady Commons carries the student version of Mathcad for $125. The Matlab student version version can be pur purchased chased online about about $100 (credit card only) only) at: http://www.mathworks.com/products/education/student_version/sc/ Computer Spectrum should also be able to order this from MathWorks (company who makes Matlab) as well, but they do not currently keep it in stock.
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ECE 4710: Lecture #1
ECE 4710 / 7710 Communication Systems Computer Useage For those of you who do not have a home computer and/or do not want to purchase the software, Matlab is available in the ECN computer lab (W2003 EBE). Your textbook’s author has provided a set of Matlab (*.M) and Matchad (*.MCD) programs for solving selected equations and example/study problems throughout the textbook (See Section 1-5 on pg. 7 of textbook). The selected eq equations/problems uations/problems that that have the computer programs are denoted by a computer symbol : . The *.M and *.MCD files are available on my website in the “\Matlab” or “\Matchad” subdirectories. They are also available at the following web-site: http://www.couch.ece.ufl.edu
See Appendix C for Quick Start for Running M files Programming in Matlab “
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and
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ECE 4710 / 7710 Communication Systems Lecture #
Day of Week
Date
Book Sections
Topic
1 2 3 4 5
M W F M W
Aug 20 Aug 22 Aug 24 Aug 27 Aug 29
Chpt. 1 (1-6) Chpt. 1 (7-11) Chpt. 2 (1) Chpt. 2 (2-3) Chpt. 2 (6)
Introduction Information & Channel Capacity Signal Properties Fourier Transform & PSD Linear Systems Review
6 -7 8 9 10 11
F M W F M W F
Aug. 31 Sep 3 Sep 5 Sep 7 Sep 10 Sep 12 Sep 14
Chpt. 2 (7,9) -Chpt. 3 (1-2) Chpt. 3 (3) Chpt. 3 (3) Chpt. 3 (4) Chpt. 3 (5)
Bandlimited Signals & Noise Labor Day Holiday Pulse Amplitude Modulation (PAM) Pulse Code Modulation (PCM) Pulse Code Modulation (PCM) Digital Signaling Line Codes & Spectra
12 13 14 --15 16 17
M W F M W F M
Sep 17 Sep 19 Sep 21 Sep 24 Sep 26 Sep 28 Oct 1
Chpt. 3 (5) Chpt. 3 (5) Chpt. 3 (6) --Chpt. 4 (1-2) Chpt. 4 (3-4, 6-8) Chpt. 4 (16)
18
W
Oct 3
Chpt. 4 (16)
Line Codes & Spectra Synchronization Intersymbol Interference First Exam Modulated Signals Bandpass Spectrum & Power Tx’s & Rx’s Rx’s
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Communication Systems
Designed to transmit information between two points
Electrical systems do this via electrical signals
Time-varying voltage in electrical circuit » “Wired” communic communication ation
Time-varying EM wave propagating through air/space » “Wireless” communica communication tion
Transmission of information implies that message is not known ahead of time random
Randomness (entropy) is proportional to information content
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Communication Systems
Design and selection of information bearing waveforms is critical to successful communication
Waveform design/selection depends on:
Signal Bandwidth
Information Data Rate
Transmission Transmissi on Center Frequency
Signal Power/Energy Resistance to Noise/Interferenc Noise/Interference e
Complexity/Cost to Design Tx/Rx Circuits
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Communication History Year
Event
Inventor/Comment
1837
Samuel Morse
1864
Telegr elegraph aph EM Theory
1876
Telephon elephonee
A.G. Bell
1901
Radio Transmiss Transmission ion
G. Marconi
1921
Mobile Radio
1928
Televi elevision sion
P.T. Farnsworth Farnswort h
1933
Frequency Modulation (FM)
E.H. Armstrong
1945 1948
First Computer Information Theory
Univ. of Penn. Claude Shannon
1948
Transistor
Shockley et al.
1950
Error Coding
Hamming
James Maxell
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Communication History Year
Event
Inventor/Comment
1958
Integrated Circuit
Jack Kilby (TI)
1965
Satellite Communications
1971
Microprocessor
Intel
1972
Cellular Radio Concept
Motorola/Bell Labs
1981
Personal Computer
IBM
1983
1st Generation (1G) Cellular
Analog AMPS
1989
GPS Satellites
U.S. Military
1991
2G Digital Cellular
GSM in Europe
1995
WWW and Interne Internett
1998
2G CDMA Cellular
Qualcomm/Sprint PCS
2003
3G Cellular Standards
Whole World
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Analog vs. vs. Digital
Information Source Analog:
continuous range of states continuous states
» Microphone: output output voltage signal with with continuous continuous
range of amplitudes Digital: finite set of possible states » Computer Keyboard: Keyboard: finite finite set of characters characters
Waveform = signal voltage vs. time Analog continuous amplitude
Digital discrete set of amplitudes
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Digital Communication System
Typically uses BOTH analog AND digital waveforms Analog:
carrier waveform (sinusoid) carrier (sinusoid) for transmission transmission
Digital: discrete values for amplitude, frequency, or phase
used to represent information bits
Binary Digital Waveform 2 states for each digital symbol, e.g. 0, 1
0
1
0
1
0
1
0
1
-ary Digital Waveform -ary
M
M -states -states
for each symbol
00
01 00
10 00 11
00 01
M = 4 states 2 bits/symbol
# Bits/Symbol = log
2
M ) ( M
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Deterministic vs. Random
Waveform Classification
Deterministic: waveform modeled or represented completely as a function of time, e.g. s (t ) = A cos (w t + f ) Random/Stochastic: cannot be completely specified as a function of time
Recall that randomness = information
Waveforms must be random to carry significant information
Source/Information Waveform: each symbol can be deterministic but information stream is random Noise is also a random signal Probability/Statistics must be used to analyze
performance of any communication system
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Digital Communication System
Digital communication systems have MANY MANY advantages over analog systems including:
Data encryption for security/priv security/privacy acy
Combine multiple information types (voice, video, data) on a single transmission channel
Resistant to noise, fading, and interference » Small error probability probability even even with large large interference
Error detection and correction using digital codes
Implementation using all digital circuits
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Basic Communication System Information Source
Transmission Channel
Baseband Signal Processing
m (t)
r (t)
s (t)
m (t)
Information Sink
˜
Noise Modulation & Carrier Circuits
Transmitter Tran smitter (Tx)
n (t)
Demodulation & Carrier Circuits
Baseband Signal Processing
Receiver (Rx)
Goal: Design system to transmit information, m(t ), with as little deterioration as possible within design constraints of signal power, signal bandwidth, and system cost
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System Components
Baseband signals signal centered at f = 0
m(t) : input information signal (voice, data, video, etc.)
m(t) : received information signal distorted/corrupted by noise, interference, non-linearities, etc. ˜
Baseband Signal Processing
Encoding of information “Source coding” coding”
Filtering to minimize signal bandwidth
Error coding to protect information
“Channel Coding” Coding”
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System Components
Tx Carrier Circuit
Converts processed baseband signal into frequency band that is appropriate for transmission thru channel
Tx output s(t) is called a “bandpass” signal signal
» Car Carrie rierr fre freque quency ncy,, f c, is center frequency of bandpass signal
m(t) s(t) s(t) conversion or mapping is called “modulation” “modulation”
Channel : Two major categories
Wire
Wireless
Introduces significant distortion and impairments
coaxial, twisted pair, & fiber optic cables
mobile radio, broadcast, satellite channels
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System Components
Channel Impairments Attenuation,
multipath echoes, multipath echoes, fading, noise, noise, interference,
etc.
Channel characteristics characteristics can be fairly stable (wired) or change rapidly as function of time (mobile radio) » Time-varying channel is is difficult difficult to model
Noise » Man-made: computers, computers, motors, motors, car ignition, ignition, other users (cellular phone) » Natural: thermal “background” noise, lightening, etc. etc.
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System Components
Receiver Carrier Circuit (Rx)
Takes corrupted signal from channel and converts down to baseband signal demodulation (mod/dem = modem)
Rx Baseband Signal Processing
Cleans up distorted baseband signal and delivers estimate of the source information signal m(t) ˜
Filtering, bit detection, error detection/correction
Performance measures Analog
N ) ratio output signal-to-noise (S / N
Digital probability of bit error or “Bit Error Rate (BER)” (BER)”