37
Overview of Spread Spectrum Communication Dong In Kim College of Info/Comm Engineering Sungkyunkwan University
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
cont …
CDMA for Cellular Telephone
User Capacity
Frequency Reuse
cont …
Near-Far Problem
Power Control
Analysis of MA Capability
Gaussian Approximation
Transmitter Model
cont …
cont …
Spreading Sequence
cont …
cont …
cont …
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.
cont …
This sequence generator produces 33 Gold sequences of N=31.
+
+ + +
+
a
b
Gold sequences
The preferred pair of primitive polynomials:
G1(D)=1+D2+D5, G2(D)=1+D+D2+D4+D5.
cont …
This sequence generator produces 8 Kasami sequences of N=63
+
+
+
a
b
Kasami sequences
The two generator polynomials:
G1(D)=1+D+D6, G2(D)=1+D+D3.
MA Channel Model
Receiver Model
cont …
cont …
Decision Statistics
