Transcript UWB Tutorial v2.0 - National Spectrum Management

UWB Technology
Michal Freedhoff, Ph.D.
Director of Regulatory Policy
[email protected]
TIME DOMAIN
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May, 2001
What Is Ultra-Wideband?
 A wireless technology that uses
ultra-low power (microwatts) to
deliver megabits across multiple
gigahertz
 It can fuse high performance
communications with precision
location and high resolution radar
sensing
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What Is Ultra-Wideband?
 Definition
2
fu-fl

fu+fl
0.25
Where:
fu= upper 10 dB down point
fl = lower 10 dB down point
 At Part 15 powers (a few tens of microwatts
total - across several GHz), cannot be reliably
measured below 10 dB down points
 UWB signals at higher center frequencies will
have larger bandwidths
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Time Modulated Ultra-Wideband
 Not a sinewave,
but millions of
pulses per second
500 ps
 Time coded to
make noise-like
 Channelization
 Anti-jam
 Smooths spectrum
Amplitude
Randomized Time Coding
0
-40
Time
“0” “1”
 Pulse position
modulation
Power Spectral Density (dB)
Frequency (GHz)
-80
Random noise signal
1
2
3
4
5
Frequency (GHz)
d d
d = 125 ps
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May, 2001
Time Domain UWB –
Three Technologies in One
 Enables vast
improvements
 Wireless
communications
 Precision tracking
 Radar sensing
PulsON,
A Chip Based Solution
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Unique Benefits of UWB
Save and Protect Lives
 Victims of crimes and disaster
 Police, fire, rescue personnel
 Workplace, environmental and highway safety
 Military and civilian security
Independent Living/Better Health Care
 Aged and disabled independence
 Diagnosis and treatment
 Lower costs
“Digital Divide” relief
 Lower cost indoor broadband
Complement and Extend Reach of GPS
 Aviation safety
Worldwide Race - Breakthrough Technology
 Jobs/Economic Development
 Global Technology Leadership
 Relieve “spectrum drought”
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What is UWB’s Role in the
Future of Broadband Wireless
Broadband To The Home...
Optical
Satellite
DSL
Cable Modem
FTTH
MMDS
CATV
POTS
The Challenge: “Broadband Thru The Home”
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TM-UWB Enables…
In-Building 3-D Precision Location & Tracking
(indoors +/- 3 cm)
People Tracking
– DOC SBIR to track firefighters
– DOD to track soldiers in urban
training scenarios
Asset Tracking
– Partnership with GE and grant
from NIST to track medical
equipment in hospitals
Proposed TimeTagTM
Design for
Precision Tracking
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Radar Prototype
 Waiver from FCC to
sell a limited number
of Radarvision
devices
 Through wall motion
sensing for law
enforcement, and
earthquake rescue
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May, 2001
Unlicensed Spectrum
Not to scale
2.4 GHz
UNII Bands
Part 15
1
2
3
4
5
6
Frequency (GHz)
 Although UWB technology operates at the same or
lower power levels currently allowed for numerous
applications under the FCC’s Part 15 rules, a
change of the rules is needed to accommodate this
new form of wireless technology
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US Regulatory Status of UWB
 Presently billions of digital devices that
emit UWB-like signals (laptops, PDAs,
etc.)
 Operate in the US under unlicensed
“Part 15” rules
 Basic requirement of Part 15:
 Thou shalt not create harmful
interference
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What is Harmful Interference?
 The FCC must decide what constitutes harmful
interference. This is a critical spectrum management
issue.
 US Statutory definition of harmful interference (FCC)
 “Interference which endangers the functioning of a
radionavigation service or other safety services or seriously
degrades, obstructs or repeatedly interrupts a radio
communications service operating in accordance with these
[international] Radio Regulations.” 47 CFR 2.1
 US NTIA definition
 NTIA ITS website adds that harmful interference “must cause
serious detrimental effects such as circuit outages and message
losses as opposed to interference that is merely a nuisance or
annoyance that can be overcome by appropriate measures.”
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Rule Change: “Noise is Noise”
Regardless of What Causes It
 Radio-wave power (noise) causes interference
 Interference has nothing to do with whether the noise source is an
“intentional” or “unintentional” emitter
 Appropriate measure is power level, not “intent”
 UWB power limits set by FCC should be:
 Equivalent to power limits for both “unintentional” and “spurious”
emissions (-71dBW/MHz, the Part 15 power level)
 Lower than out-of-band power limits allowed for licensed services
 e.g., PCS and MSS are allowed to emit slightly more energy in
restricted bands than all Part 15 devices
 UWB power limits are no different than levels emitted by
existing Part 15 devices. Therefore, UWB should be
treated like other Part 15 devices:
 Intentional vs. unintentional distinction is unnecessary
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GPS Coexistence Testing
 Johns Hopkins Applied Physics Laboratory
 Sponsored by Time Domain
 Analyzed data taken by Applied Research
Laboratory, University of Texas (ARL:UT)
 Comprehensive testing produced 20 GB of data
including conducted and radiated testing of
multiple receiver types and UWB modes as well
as other digital devices operating at Part 15 power
 Developed 12 measures of GPS receiver
performance related to number of satellites,
position accuracy, and reacquisition time
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An Example Graph from
JHUAPL Report
Asymptotic curve with noticeable effects starting at 3 meters
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JHUAPL Analytic Results
 TM-UWB emissions are white noise-like signals
that can be modeled as average power
 Multiple TM-UWB emissions add as average
power
 TM-UWB emissions resemble emissions from
devices operating at Part 15 power levels– unkeyed walkie-talkie
 Developed theoretical model that accurately
predicted both ARL:UT and other experimental
data
 DoD Joint Spectrum Center recently showed that
NTIA and UT/JHU data largely say the same
thing. TDC performed similar analysis
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Aggregate Issue
 Why isn’t the night sky as bright as the day?
 Can’t be an aggregate issue on the large
scale if the average propagation path is less
than free space
 Except over very short ranges, free space
paths don’t exist
 At the power levels that the FCC may
authorize, applications must be short range
applications
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Conclusions
 The benefits of UWB are unique, and
in many cases cannot be realized
using other technologies
 UWB can be introduced at Part 15
power levels without causing harmful
interference
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May, 2001