Mobile communications base-station array antenna

104 Pages·2005·3.04 MB·English

Mobile Communications Base-station Array Antenna:
Characterization of Environment
by
Trent McKeen
B.A.Sc., Simon Fraser University, 1993
THESIS SUBMITTED IS PARTIAL FULFILLMENT OF THE
REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE
in the School of Engineering Science
O Trent McKeen 1995
SIMON FRASER UNIVERSITY
August, 1995
All rights reserved. This work may not
be reproduced in whole or in part, by photocopy or other
means, without permission of the author.
APPROVAL
NAME: Trent McKeen
DEGREE: Master of Applied Science (Engineering Science)
TITLE OF THESIS: Mobile Communications Base-station Array Antenna: Characterization of
Environment
EXAMINING COMMITTEE:
Chairman:
Dr. Paul Ho, P. Eng.
Associate Professor
Schqol of Engineering Science, SFU
Senior Supervisor:
-apeon, P.Eng.
Associate Professor
School of Engineering Science, SFU
Supervisor:
Dr. Id! Parameswaran
Assistant Professor
School of Engineering Science, SFU
- -
External Examiner: - . .-
Mr. Pete McConnell
Principle Engineer
Sierra Wireless Inc.
DATE APPROVED:
PARTIAL COPYRIGHT LICENSE
I hereby grant to Simon Fraser University the right to lend my thesis,
project or extended essay (the title of which is shown below) to users of the
Simon Fraser University Library, and to make partial or single copies only for
such users or in response to a request from the library of any other university, or
other educational institution, on its own behalf or for one of its usrs. I further
agree that permission for multiple copying of this work for scholarly purposes
may be granted by me or the Dean of Graduate Studies. It is understood that
copying or publication of this work for financial gain shall not be allowed without
my written permission.
Title of Thesis/Project/Extended Essay
"Mobile Communications Base-Station Array Antenna:
Characterization of Environment"
Author:
August 16.1995
(date)
Abstract
The demand for mobile telephone services is rapidly increasing while the frequencies allocated for this
purpose have remained unchanged. In order to achieve higher user capacity, within the existing infras-
tructure, innovative system designs are being sought. Phased array base-station antennas have been
proposed by many authors as a means of achieving higher spectral efficiency.
This paper examines the behavior of a phased array base-station antenna in a real urban environment.
Field tests were performed to characterize the fading environment as seen by a multi-element base-station
antenna. The primary goal of the field tests was to obtain the cross-correlation matrix for the different
antenna elements. All the hardware designed and built for the field tests is documented, as well as the
methods used to extract and compile the measured data.
As equipment for mobile phased array systems is developed, there will be a demand for a "spatial
channel simulator" - a fading environment simulator which has the ability of simulating multi-element
(directional) antennas. This paper also examines the development of a spatial channel simulator. It
introduces the mathematical model used in its development as well as documents the hardware and
software components of the system. Finally, the simulators performance is compared to true field test
data. The results show that the statistical properties of the signals generated by the simulator very
accurately duplicate those of signals encountered in the field.
i i i
ACKNOWLEDGMENTS
First I would like to thank my senior supervisor, Dr. Shawn Stapleton for all his insight and help.
I would also like to thank Pete McConnel for his technical reference and allowing me to shop at Pete's "You
Name It I've Got It" Electronics Emporium. Its a strange currency he uses and he doesn't offer change.
A special thanks to Sirooj Rambaran for his enormous help in putting the project together. Thank you
Sirooj.
Glennayre, in particular Flaviu Costescu and Rob Marchetto, deserve mention for allowing us to use
Glennayre's facilities to perform the field test measurements.
Finally, the two other students I worked with on the project, Xavier Carbo and Sarkis Teghararian, were
excellent people to work with. I could not imagine better colleges.
Contents
1 introduction 1
1.1 Synopsis of Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Phased Array Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 Spatial Channel Simulators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 multipath interference 5
2.1 Synopsis of Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Standard Rayleigh Fading Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2.1 The Mathematical Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2.2 Power Spectra of the Fading Signal . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.3 Level Crossing Rate and Duration of Fades . . . . . . . . . . . . . . . . . . . . . . 9
2.2.4 A Fading Channel Simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.3 Directional Antenna Rayleigh Fading Model . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.3.1 Mathematical Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3.2 The Spatial Channel Simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
spatial channel simulator
3.1 Synopsis of Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 General Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3 The DSP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.1 Generation of Gaussian Random Samples . . . . . . . . . . . . . . . . . . . . . . .
3.3.2 Gaussian Sample Combination Algorithm . . . . . . . . . . . . . . . . . . . . . . .
3.3.3 Spectral Shaping Through Finite Impulse Response (FIR) Filtering . . . . . . . .
3.3.4 I and Q Phase Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4 14 Channel D/A Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.5 Reconstruction Filter Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.6 Quadrature Modulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 spatial channel simulator performance
4.1 Synopsis of Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2 The Measurement Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3 Single Channel Performance
4.3.1 Measured Probability Density Functions . . . . . . . . . . . . . . . . . . . . . . . .
4.3.2 Other Channel Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.3 Time Domain and Frequency Domain Plots . . . . . . . . . . . . . . . . . . . . .
4.4 Spatial Channel Simulator Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5 phased array antenna 42
5.1 Synopsis of Chapter . . . . . . . . . . . . . 42
5.2 Hardware Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.2.1 Mobile Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.2.2 Base-Station Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.2.3 Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3
5.2.4 Data Digitization and Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
5.3 The Field Test Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 9
5.3.1 Mobile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
5.3.2 Base-station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1
5.4 Description of Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
5.4.1 Single Tone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
5.4.2 Eight Tone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
5.4.3 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
5.4.4 Data Plus Interferer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
6 field tests 65
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1 Synopsis of Chapter 65
6.2 Field Test Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
6.3 Single Channel Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
6.3.1 Measured Probability Density Functions . . . . . . . . . . . . . . . . . . . . . . . . 67
6.3.2 Other Channel Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
vii
6.3.3 Time Domain and Frequency Domain Plots . . . . . . . . . . . . . . . . . . . . . . 71
6.4 Antenna Element Correlation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
6.4.1 Correlation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
6.4.2 Explanation of Correlation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
6.5 Vehicle Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
7 conclusions 86
7.1 The Spatial Channel Simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
7.2 The Phased Array Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
...
Vlll
List of Figures
2.1 Rayleigh Fading Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Rayleigh. Gaussian Distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3 Fading Channel Simulator Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.4 Fading Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1 Correlation Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2 Spatial Channel Simulator Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.3 Programmed Cross-Correlation Matrix (both I and Q) . . . . . . . . . . . . . . . . . . . . 21
3.4 Spectral Shaping Filter Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.5 14 Channel DAC One channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
-
3.6 14 Channel DAC Channel Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
-
3.7 Reconstruction Filter Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.8 Switched Capacitor Filter and Anti-Aliasing Filters . . . . . . . . . . . . . . . . . . . . . . 29
4.1 Simulated Envelope Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.2 Simulated Phase Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34