Download - Intel Smart Antenna Workshop
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8/4/2019 Intel Smart Antenna Workshop
1/15
February 26, 2004Slide 1
Little Wireless and SmartLittle Wireless and SmartAntennasAntennas
Jack H. Winters
2/26/04
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8/4/2019 Intel Smart Antenna Workshop
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February 26, 2004Slide 2
OUTLINE
Smart antennas Implementation issues Appliqu
Conclusions
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8/4/2019 Intel Smart Antenna Workshop
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February 26, 2004Slide 3
Smart Antennas for WLANs
TDD operation (only need smart antenna at access point or terminal for performance improvement in
both directions)
Interference suppression Improve system capacity and throughput Supports aggressive frequency re-use for higher spectrum efficiency, robustness in the ISM band (microwave
ovens, outdoor lights)
Higher antenna gainExtend range (outdoor coverage) Multipath diversity gain Improve reliability MIMO (multiple antennas at AP and laptop) Increase data rates
APSmart
Antenna
Interference
Smart Antennas can significantly improve the performance of
WLANs
APSmart
Antenna
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8/4/2019 Intel Smart Antenna Workshop
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February 26, 2004Slide 4
Implementation Issues
Smart antenna is a multibeam or adaptive antenna array that tracks the wireless
environment to significantly improve the performance of wireless systems
Adaptive arrays in any environment provide:
Antenna gain of M
Suppression of M-1 interferers
In a multipath environment, they also provide:
M-fold multipath diversity gain
With M Tx antennas (MIMO), M-fold data rate increase in same channel with same total transmit power
SIGNAL
OUTPUT
SIGNAL
INTERFERENCE
INTERFERENCEBEAMFORMER
WEIGHTS
SIGNAL
OUTPUT
BEAM
SELECT
SIGNAL
BEAMFORMER
Adaptive Antenna ArraySwitched Multibeam Antenna
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8/4/2019 Intel Smart Antenna Workshop
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February 26, 2004Slide 5
Multiple-Input Multiple-Output (MIMO) Radio
With M transmit and M receive antennas, can provide M independent channels, to increase data rate M-fold with no increase in total transmit power (with sufficient multipath) only an increase in DSP
Indoors up to 150-fold increase in theory Outdoors 8-12-fold increase typical
Measurements (e.g., AT&T) show 4x data rate & capacity increase in all mobile & indoor/outdoorenvironments (4 Tx and 4 Rx antennas)
216 Mbps 802.11a (4X 54 Mbps)
1.5 Mbps EDGE
19 Mbps WCDMA
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8/4/2019 Intel Smart Antenna Workshop
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February 26, 2004Slide 6
WEIGHT GENERATION TECHNIQUES
For Smart Antenna: Need to identify desired signal and
distinguish it from interference
WeightGeneration
Blind (no demod): MRC Maximize output powerInterference suppression CMA, power inversion, powerout-of-band
Non-Blind (demod): Training sequence/decision directed reference signalMIMO needs non-blind, with additional sequences
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8/4/2019 Intel Smart Antenna Workshop
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Digital vs. Analog Implementation
Analog Advantages: Digital requires M complete RF chains, including M A/D and D/A's,versus 1 A/D and D/A for analog, plus substantial digital signalprocessing The cost is much higher for digital An appliqu approach is possible - digital requires a completebaseband
Digital Advantages: Slightly higher gain in Rayleigh fading (as more accurate weights
can be generated) Temporal processing can be added to each antenna branch mucheasier than with analog, for higher gain with delay spread Modification for MIMO (802.11n) is easier than with analog
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8/4/2019 Intel Smart Antenna Workshop
8/15February 26, 2004Slide 8
RF
Appliqu(Spatial
processing
only)
RF
Processor
Baseband/MAC
Processor,
Host Interface
Wireless
Transceiver
Appliqu
Conforms to 802.11 standard (blind beamforming with MRC)
Appliqu configuration requires minimal modifications to legacydesigns
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8/4/2019 Intel Smart Antenna Workshop
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Smart Antenna WiFi(PCMCIA Reference Design)
Appliqu Architecture Plug-and-Play to legacy designs
Motia
Smart Antenna
RF Chip
RF
Processor
Baseband/MAC
Processor
Legacy Transceiver
Partners: Intersil/Globespan,
Maxim/TI, RFMD, Atmel
PCMCIA
-CARDBUSInterface
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8/4/2019 Intel Smart Antenna Workshop
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802.11b Packet Structure
192 symbol Long Preamble
Preamble
128 Barker
BPSK
SFD PHY H
16 Barker
BPSK
48 Barker
BPSK
Data from MAC
Barker
BPSK/QPSK
(CCK 5.5/11Mbps)
MPDU
96 symbol Short Preamble
Preamble
56 Barker
BPSK
SFD PHY H
16 Barker
BPSK
24 Barker
QPSK
Data from MAC
Barker
BPSK/QPSK
CCK 5.5/11Mbps
MPDU
Time permits weight generation
20
s
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8/4/2019 Intel Smart Antenna Workshop
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Performance Comparison - All four data rate
y = . e44444- . x4444
4
.00
.00
.00
.00
.00
.00
.00
.00
-44 -4 4 4 44 44 44 44 44
SNR (dB)
FE
. spec44444Mbps Baseline44
Mbps Baseline4. Mbps Baseline44Mbps Baseline4Mbps -ant44 4
. Mbps -ant44 4Mbps -ant4 4Mbps -ant4 4
Theoretical for short packet
Achieves a 12 to 14 dB gain over a singleantenna
802.11b Performance with Fading
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8/4/2019 Intel Smart Antenna Workshop
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2 AntennaSelection
Adaptive
One Side
Adaptive
Both Sides
TheoreticalBound Both
Sides
6.1 dB 12.8 dB 18.0 dB 22.2 dB
Performance Gain over a Single Antenna in a
Rayleigh Fading Channel
802.11b Beamforming Gains with 4
Antennas
2X to 3X Range + UniformCoverage
3X to 4X Range + UniformCoverage
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8/4/2019 Intel Smart Antenna Workshop
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802.11n
Requirements for 802.11n: >100 Mbps in MAC
>3 bits/sec/Hz
Backward compatible with all 802.11 standards Requires MAC changes and may require MIMO:
4X4 system (?)
Next standards meeting in Orlando
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8/4/2019 Intel Smart Antenna Workshop
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802.11n Process
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8/4/2019 Intel Smart Antenna Workshop
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Summary and Conclusions
Current research is finding ways to implement
smart antennas in a variety of commercial
systems:
Reusing same silicon where possible to reduce cost Minimizing modifications to existing systems
Staying within the standards
Meeting each systems unique requirements