UWB The Potential and the Controversy

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UWB - The Potential and the Controversy
Consulting Services in Radio Technology and
Spectrum Policy

• Michael J. Marcus, Sc.D., FIEEE
• Director
• Marcus Spectrum Solutions, Paris, France
• mjmarcus_at_alum.mit.edu
• www.marcus-spectrum.com

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Likely UWB Market Target

• Plus
• Ground penetrating radar
• Through-the-wall radar
• Tracking systems

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Other UWB Advantages

• Doesnt need licensed dedicated spectrum
• Low power consumption
• Small semiconductor size
• Ranging/location as a byproduct of communications

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Some UWB Technical History Sources

• http//www.aetherwire.com/
  CDROM/General/papers.html
• http//www.multispectral.com/
• history.html

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UWB Background Technology

• Early sparkgap radio systems were similar in some
  ways to UWB and occupied large bandwidths
• Growth in demand for capacity necessitated
  spectrum sharing
• Any orthogonal multiplex system could share
  spectrum
• A basis set made of sinusoids was the only
  available one in early days of radio and remains
  viable for most uses today
• Sinusoids replaced sparks and Class B emissions
  banned by ITU

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UWB Background Technology

• Like the invention of the computer, origin of
  UWB somewhat convoluted
• TD analysis of microwave networks is one origin
• Work of Prof. Harmuth at Catholic University of
  America in 1970s on Walsh functions as an
  alternative basis set was another

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UWB Background Technology

• Ross 1973 patent may be the first
• By 1989, Sperry Rand had more than 50 UWB patents
  but no civil applications
• 1987 Time Domain Corp. founded
• Initial work all government

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UWB BackgroundRegulation
Where did this come from?
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UWB BackgroundRegulation

• Why underlays?
• White space problem
• In the real world there are significant gaps in
  spectrum use at a given place at a given time
• Major spectrum policy issue is how to recycle
  this white space responsibly
• Growing demand for short range, high capacity
  links to supplement existing IT systems

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UWB BackgroundRegulation

• What is harmful interference
• ITU definition came from a different era where
  interference was more binary
• Is interference that is small compared to
  naturally occurring problems harmful
• US Northpoint 12 GHz DBS/BSS precedent
• Outage increase lt5 of rain-related outage is OK

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UWB BackgroundRegulation

• 1981-85 FCC Docket 81-413
• Intended to explore potential of spread spectrum
  in civil applications
• Resulted in ISM bands for unlicensed, e.g. Wi-Fi
• Stimulated development of CDMA cellular
• Initial proposals were broad enough to include
  UWB
• All proposals were broadly criticized by existing
  radio users
• No real advocates for underlays
• ISM band chosen as a safe place to explore CDMA

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UWB BackgroundRegulation

• 1989 rewrite of FCC Part 15 rules aimed to
  generalize concepts and decrease specific rules
  for specific devices
• New 15.209 allowed unlicensed use on most
  frequencies subject to PC emission limit
• At insistence of NTIA, certain bands are exempted
  from any such emissions - 15.205
• But, please note that real PCs do not actually
  emit all the time on all frequencies

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Roots of FCC UWB Decision
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St. Valentines Day 2002The Perfect Storm of
Spectrum Policy

• Why did UWB get authorized when previous attempts
  got nowhere?
• Bush administration appoints 3 political
  appointees with technical business backgrounds in
  key positions
• Steve Price/DoD
• Mike Gallagher/NTIA
• Ed Thomas/FCC

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St. Valentines Day 2002The Perfect Storm of
Spectrum Policy

• In previous years vested interests had blocked
  almost all consideration of underlays
• Realities of new millennium allow issues to be
  addressed on their merits
• Approval complicated by concerns over 2
  relatively recent developments
• GPS/Assisted (indoor) GPS
• CDMA cellular

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UWB BackgroundRegulation

• .com Boom in late 1990s stimulates interest in
  novel radio technologies
• Serious money could be made in IPOs of high
  tech firms
• Time Domain Corp. raises funding estimated at
  50-100M for development of UWB and the
  regulatory fight needed to get it approved
• Possibly 50 budgeted for regulatory fight

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UWB BackgroundRegulation - UK Version

• UK Ofcom has attempted to balance costs and
  benefits of UWB
• US focus was declaring costs to be de minimis
• But analysis is only as good as assumptions

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ITU-R

• Good News
• TG1/8 will complete its work in October
  2005
• Expected to reach consensus on 3 documents
• Bad News
• Unlikely to reach consensus on key document

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UWB EMC Analysis Issues

• Key to UWB Policy Development
• It is easy for both sides to be blinded by
  ideology in analyzing novel EMC issues posed by
  UWB
• It is tempting to apply existing EMC standards
  out of the context for which they were intended
• and which may not have been well documented

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Basic UWB EMC Issues

• Receivers only see UWB power within their receive
  bandwidth
• If PRF is greater than receive bandwidth and
  pulses dithered UWB appears noise-like
• If PRF is less than receive bandwidth UWB appears
  impulsive

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Basic UWB EMC Issues

• UWB emitter creates a local increase in noise
  which decreases with distance depending on
  appropriate propagation model
• For some weak desired signals this can adversely
  impact SNR
• Burnthrough -change in geometry can cure SNR
  problem

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Basic UWB EMC Issues CDMA

• In basic decade CDMA cellular has become common
• CDMA systems are impacted differently by noise
  increases than FDMA or TDMA
• In an ideal RF noise environment, UWB would
  decrease capacity of CDMA LM systems
• Impact in realistic environments more complex

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Aggregation

• Aggregation continues to be the Count Dracula
  of spectrum management
• Aggregation actually is a real concern, but is
  exaggerated by some

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Aggregation

• Aggregation is the possible accumulation of
  undesired signal power at a victim receiver
  resulting from many UWB transmitters.
• Depends on various factors such as minimum
  distance to closest UWB source and nature of
  propagation
• In most real applications there is a practical
  minimum distance or cutoff of uncooperative
  signal sources
• Modeling UWB location as a pair of i.i.d. random
  variates is unrealistic

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Aggregation Closest Interferer Issue

• Modeling UWB location as a pair of i.i.d. random
  variates is simple but in the real world there is
  a minimum distance for unrelated sources
• Each person has some space around them under
  there own control 0.5 - 2m
• Each residence has a similar space 3 - 20m
• These bound location of closest interferer

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Aggregation

• Aggregation is a real threat in cases of free
  space paths such as in ground-air communications
  and satellite uplinks
• In these situations victim could see a large
  number of UWB devices with free space paths
• However, most applications involve terrestrial
  paths and victims with more complex propagation
  characteristics

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Aggregation

• With square power law power will aggregate with
  number of users
• But location of closest user is a key factor

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Aggregation

• For ? gt2 in propagation, typical of terrestrial
  paths, integrals summing to infinity converge so
  aggregation converges
• Nearest interferer is still key

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Aggregation

• For ? 2 (square law) integral of power received
  at a victim receiver increases as upper limit of
  integral increases
• For ? 4 integral converges

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Microwave Landing System (MLS)
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Radar Issues
To understand these issues you have to be
realistic about antenna siting
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Radiation Hazards

• Aircraft 300 V/m peak
• FAA, 14 CFR Parts 21 25, Federal Register May
  16, 1988
• Critical Medical Electronic Devices
• IEC 3 V/m
• AF report SAM-TR-76-4 (e.g. Pacemakers etc.)
  200 V/m peak
• ? ASR-9 1.4 km ? TDWR 4.3 km
• ARSR-4 1.1 km ? NEXRAD 4.5 km
• Personal Exposure Limit (PEL) 1 mW/cm2
• DOD instruction 6055 and ANSI C95.1-1982
• Fuels 3.1 kV/m peak
• DNA 4284-F-SAS-1 Dec 1979
• Explosives 12.4 kV/m
• DNA 4284-F-SAS-1 Dec 1979

It is not reasonable to base regulations on
geometries that put the UWB user in field
strengths that are not safe not safe
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UWB Schism
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Mike Gallagher (NTIA) on UWB Emission Masks
http//www.ntia.doc.gov/ntiahome/speeches/2005/MGa
llagher_UWB_05212005.ppt

• A technically based approach (measurements and
  analysis) was used to develop the UWB emission
  limits necessary to protect the radio frequency
  spectrum used by GPS as well as other current and
  future radionavigation satellite systems.
• To date, all credible studies have shown the
  U.S. developed UWB emission limits adequately
  protect GPS receivers (based on 2 meter
  distance separation and protection of assisted
  GPS receiver technology).

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UWB Controversy

• While Time Domain Corp. deserves credit for its
  pyrrhic victory in getting UWB regulations in US,
  its sometimes outrageous claims also incited
  opponents
• Most notable UWB can be used for a cellular
  service without buying a license

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Please Be Careful Making Claims

• Wire free Harmony The combination of broader
  spectrum, lower power and pulsed data means that
  Ultra-Wideband causes significantly less
  interference than conventional narrowband radio
  solutions while safely coexisting with other
  wireless technologies on the market.
  http//www.uwbforum.org
• No harmful interferenceThanks to its low
  spectral density, unlicensed UWB radio emissions
  do not add up to cause harmful interference to
  other radio systems operating in dedicated bands.
  In fact, normal propagation attenuation causes
  the signals to dissipate faster than they can add
  up http//www.commsdesign.com/design_corner/OEG200
  20301S0021
• Both of these claims are true to a certain degree
  -- but also leave out some key fine print

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A Historic Slide That Still Holds Truth
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UWB is Coming!

• A 37-inch high definition television from
  Chinese company Haier was shown using an
  integrated UWB link to a digital media server.
  The products will ship in the Chinese market in
  the last quarter of 2005 and in the US in 2006.
  ZDNet UK June 22, 2005
• Research firm West Technology Research Solutions
  says that when Freescale Semiconductor ships its
  DS-UWB chips in the third quarter of this year,
  it will spur "significant economic growth" in
  ultrawideband circles. They expect DS-UWB
  components to have a market worth 482 million by
  2010, with annual shipments in consumer
  electronics alone hitting around 38 million units
  by 2009.

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UWB - A Pragmatic View

• UWB is cleared for the US market and is coming
• If it meets real consumer needs and predictions
  of no EMC problems are confirmed in actual use --
  spread to other countries is inevitable
• Lets get ready for it!

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UWB - The Potential and the Controversy
Consulting Services in Radio Technology and
Spectrum Policy
Thanks for Listening Have a Great Conference!

• Michael J. Marcus, Sc.D., FIEEE
• Director
• Marcus Spectrum Solutions, Paris, France
• mjmarcus_at_alum.mit.edu
• www.marcus-spectrum.com