Transcript Enabling Technology for MIMO Systems on Mobile Military

Antenna and Wireless System Research
in the ICWS
ICWS Symposium, September 7, 2007
Prof. Jennifer T. Bernhard
President-Elect, IEEE Antennas and Propagation Society
Electromagnetics Laboratory
Department of Electrical and Computer Engineering
University of Illinois at Urbana-Champaign
[email protected]; http://antennas.ece.uiuc.edu
Electromagnetics Laboratory
Overview
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Introduction
Unique Facilities
Research Sample: Antenna Reconfigurability
System Benefits of Reconfigurability
Conclusions
Electromagnetics Laboratory
Introduction: Antenna Research at Illinois
• Current Research Group
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13 Graduate Students
– 3 Undergraduate Students
• Facilities
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Bit Error Rate Measurement System
Vector Network Analyzers to 50 GHz
Anechoic Chamber/Wireless Wind Tunnel
Multiple Simulation Packages
» HFSS, CST, IE3D, XFDTD, Wireless Insite, WinNEC, ADS,
MATLAB, etc.
– In-house Fabrication and Prototyping Facilities
– In-house simulations in collaboration with the UIUC Center for
Computational Electromagnetics (antennas, propagation, etc.)
• Acknowledgments
– Funding from NSF, US ARO, Intel, Motorola, Samsung, and
others
Electromagnetics Laboratory
Wireless Wind Tunnel – New in 2007
A testbed for
repeatable
experimental
evaluation of wireless
system protocols.
New fully shielded, fully anechoic chamber
Electromagnetics Laboratory
Bit Error Rate Measurement of Antennas
New measurement system provides a
powerful tool for the investigation of
the complex relationship between
antenna and array characteristics
and ultimate system performance.
Rcv 3.525
GHz Patch
Xmit Horn
Anechoic Chamber
Measurement Lab
IF
RF
AMPLIFIER
(83050A)
Channel BW = 70 MHz
I IN
Q IN
89600 Vector
Signal Analyzer
10 Msym/s
Electromagnetics Laboratory
B
89600 Software
11667
Power
Splitter
RF OUT
RF IN
CW SIG GEN
8247C
(3.475 GHz
Carrier)
dB
-3
E4443A Spectrum
Analyzer
-3
d
I OUT
Q OUT
QAM 128
LO
RF IN
Channel BW = 40 MHz
QAM 128
10 Msym/s
IF
LO
RF
4438C Vector
Signal Generator
RF OUT
(80 MHz
Baseband)
Computer
Research Sample: Antenna Reconfigurability
Antenna Reconfigurability: The capacity to change
an individual radiator’s fundamental operating
characteristics through electrical, mechanical, or
other means.
– Traditional phasing of signals between elements in an
array to achieve beam forming and beam steering
does not make the antenna reconfigurable.
– Ideally, reconfigurable antennas should be able to
alter their operating frequencies, impedance
bandwidths, polarizations, and radiation patterns
independently to accommodate changing operating
requirements.
Electromagnetics Laboratory
Motivation for Antenna Reconfigurability
• Too many antennas for
multiple systems  Reduce
number of antennas on
platforms
• Integrated multifunctional
systems  Increase antenna
functionality in small
packages
• Expand antenna functionality
past traditional capabilities
 Develop new antennas
that meet new needs
Photos courtesy of US Coast
Guard and Motorola
Potential applications in Cognitive Radio, SDR, MIMO, and
Reconfigurable Sensing Systems
Electromagnetics Laboratory
Examples of Antenna Reconfigurability
Pattern Reconfigurable Microstrip Parasitic Array
Zhang, Huff, Cung and Bernhard, IEEE Trans. Antennas and Propagation, 2005
Electromagnetics Laboratory
Examples of Antenna Reconfigurability
Pattern Reconfigurable Spiral Microstrip Antenna with
Packaged RF MEMS Switches
Huff and Bernhard, IEEE Trans. Antennas and Propagation, 2006
Electromagnetics Laboratory
Reconfigurability in MIMO - Simulations
• Used a floor plan modeled in Wireless InSite*
• Constructed a 2x2 MIMO system using ideal isotropic
antennas spaced λ/2 apart.
Example of a Wireless InSite simulation showing the
• Processed
five antenna positions that were tested
propagation data to
calculate the capacity
of a system using
fictitious antennas
with 60 degree
beamwidths that are
fully reconfigurable
in the azimuth plane.
* Remcom Incorporated, Wireless Insite User’s Manual, Version 2.2.2, 2006.
Electromagnetics Laboratory
Theoretical Capacity Gains in MIMO
• Compared capacity data of the optimal reconfigurable
antenna configuration to an average of all configurations
and to links using isotropic antennas.
• Simulated over three
Capacity measurements at noise power = 1 nW
noise power levels:
0.1 nW, 1 nW,
and 10 nW
SYSTEM BENEFITS
Average Capacities over
all Noise Power Levels:
Optimal: 16.5 bps/Hz
Average: 3.3 bps/Hz
Isotropic: 12.2 bps/Hz
Electromagnetics Laboratory
Measured Percentage Capacity Gains
45.0
DDDD Capacity
RDDR Capacity
DRRD Capacity
RDDR Percent Improvement
DRRD Percent Improvement
40.0
Capacity (bps/Hz)
Percent Capacity Improvement
50.0
35.0
30.0
25.0
20.0
15.0
10.0
10.0
• Results show that
very large capacity
improvements are
possible, especially at
low values of SNR.
40.0
Capacity
35.0 •
improvements are
30.0
very dependent on the
25.0
propagation
20.0
environment – may be
15.0
significantly different
10.0
in a different
5.0
scenario.
15.0
20.0
25.0
30.0
35.0
40.0
45.0
 (dB)
Electromagnetics Laboratory
0.0
50.0
Conclusions
• Antennas can play an active role in
delivering improved system performance.
• The Electromagnetics Laboratory and
ICWS at Illinois have unique measurement
capabilities that help to closely link device
behavior to system performance.
• Research in the ICWS is supporting the
cooperative development of next generation
antennas and wireless systems.
Electromagnetics Laboratory