Post on 23-Mar-2022
transcript
Overview of Spread Spectrum Communication
Dong In KimCollege of Info/Comm Engineering
Sungkyunkwan University
Digital Communication System
Spread Spectrum Communication
Main Applications
Basic Techniques
Direct-Sequence SS System
Direct-Sequence SS Signal
Power Spectral Density
Processing Gain
Code Division Multiple Access
Multiple Access Capability
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CDMA for Cellular Telephone
User Capacity
Frequency Reuse
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Near-Far Problem
Power Control
Analysis of MA Capability
Gaussian Approximation
Transmitter Model
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Spreading Sequence
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Example(1) : Walsh Codes
Example(2) : m-sequences
Example(3/4) : Gold & Kasami
M. B. Pursley and H. F. A. Roefs, “Numerical evaluation of correlation
parameters for optimal phases of binary shift-register sequences,”
IEEE Trans. Commun., vol. COM-27, pp. 1597-1604, Oct. 1979.
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This sequence generator produces 33 Gold sequences of N=31.
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Gold sequences
The preferred pair of primitive polynomials:
G1(D)=1+D2+D5, G2(D)=1+D+D2+D4+D5.
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This sequence generator produces 8 Kasami sequences of N=63
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Kasami sequences
The two generator polynomials:
G1(D)=1+D+D6, G2(D)=1+D+D3.
MA Channel Model
Receiver Model
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Decision Statistics