Future Studies Current ThinkingContext and Archit ic Loe ecture
ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The...
-
Upload
hortense-mcdowell -
Category
Documents
-
view
227 -
download
0
Transcript of ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The...
![Page 1: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/1.jpg)
ECE 442 COMMUNICATION SYSTEM DESIGNLECTURE 1. MODULATIONHusheng Li
Dept. of EECS
The University of Tennessee
![Page 2: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/2.jpg)
COURSE INFORMATION
Lecturer: Husheng Li Time: 12:40pm --- 1:55pm Location: MK404 Office time: 3pm --- 4pm, everyday Office: MK644 Course website http://web.eecs.utk.edu/~husheng/ECE442_2012.htm
![Page 3: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/3.jpg)
TEXTBOOK
A. B. Carlson and P. B. Crilly, Communication Systems, 5th edition, McGraw Hill, 2010
![Page 4: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/4.jpg)
REFERENCE BOOK (1)
J.Proakis and M. Salehi, Digital Communications, 5th Edition, McGraw Hill, 2008
![Page 5: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/5.jpg)
REFERENCE BOOK (2)
A. Goldsmith, Wireless Communications, Cambridge, 2005
![Page 6: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/6.jpg)
REFERENCE BOOK (3)
D. Tse and P. Viswanath, Fundamentals of Wireless Communication, Cambridge, 2005
![Page 7: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/7.jpg)
LOGISTICS
Grading: midterm/final tests (50%), homework (4 problems each week, 25%), projects (totally 3, 25%)
Projects: Project 1: Use Matlab Simulink to simulate the
performance of a communication system (deadline: midterm)
Project 2: Use Matlab to implement the coding and decoding algorithms of convoulutional codes. Evaluate the performance (deadline: April 15th).
Project 3: A report about 4G systems (deadline: Final exam)
![Page 8: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/8.jpg)
COVERAGE
![Page 9: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/9.jpg)
DIGITAL MODULATION / DEMODULATION
Modulation means loading digital information bits into the continuous waveforms at the transmitter. Demodulation is the inverse procedure.
When a sinusoidal signal is used for radio emission, the information can be carried at the three elements: amplitude (amplitude-shift keying: ASK), frequency (frequency-shift keying: FSK) and phase (phase-shift keying: PSK).
)sin()( wtAtx
![Page 10: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/10.jpg)
ILLUSTRATION
![Page 11: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/11.jpg)
BANDPASS SIGNAL
Any modulated bandpass signal can be writtend in the following quadratic-carrier form:
The equivalent lowpass spectrum is defined as
)sin()()cos()()( twtxtwtxAtx cqcic
)()()( fGfGfG qilp
![Page 12: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/12.jpg)
AMPLITUDE MODULATION
An M-ary ASK signal can be written as
A special case is called OOK.
k
Dk kDtpatx )()(
![Page 13: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/13.jpg)
SPECTRUM EFFICIENCY The spectrum efficiency is given by
HzbpsM /log2
![Page 14: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/14.jpg)
QAM
Quadrature-carrier AM (QAM) achieves twice the spectrum efficiency of binary ASK
Signal Constellation
![Page 15: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/15.jpg)
PHASE MODULATION
An M-ary PSK signal is expressed in general by
which can be decomposed into the quadrature form.
k
Dkccc kDtptwAtx )()cos()(
QPSK 8-PSK
![Page 16: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/16.jpg)
FREQUENCY MODULATION
In FSK, the frequency is given by
kdck afff
![Page 17: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/17.jpg)
SPECTRUM OF FSK
The i and q elements of Sunde’s FSK are mutually independent.
Sunde’s FSK has very little spillover.
![Page 18: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/18.jpg)
M-ARY ORTHOGONAL FSK AND CPFSK
For the M-ary orthogonal FSK, the M keyed frequencies are spaced by
In CPFSK, the information signal is
the RF signal is then given by
2/2/12 rDfd
0
)()(k
Dk kDtpatx
t
dccc dxwtwAtx0
cos)(
![Page 19: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/19.jpg)
COHERENT BINARY SYSTEMS
A coherent bandpass system employs information about the carrier frequency and phase at the receiver to detect the message.
A noncoherent system does not need synchronization with the carrier phase, thus causing performance degradation compared with coherent bandpass system.
![Page 20: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/20.jpg)
BANDPASS BINARY RECEIVER
The filter for optimum binary detection should be matched to the difference between the two signaling waveforms.
![Page 21: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/21.jpg)
TWO ALTERNATIVE APPROACHES
Parallel matched
filter
Correlation detector
![Page 22: ECE 442 C OMMUNICATION S YSTEM D ESIGN L ECTURE 1. M ODULATION Husheng Li Dept. of EECS The University of Tennessee.](https://reader030.fdocuments.in/reader030/viewer/2022033022/56649ec65503460f94bd1097/html5/thumbnails/22.jpg)
HOW TO ANALYZE THE BIT ERROR RATE?
When the two possible outputs are z1 and z0, the bit error rate is given by
2
|| 01 zzQPe