SG8 Presentation on Tomorrow's Technological Innovations

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Exploring the Feasibility and Benefits of
Additional Uses of Unused TV Broadcast
Spectrum Carl R. Stevenson Sr. Manager,
Standards Regulatory Affairs, Agere
Systems Chair, IEEE 802.18 Radio Regulatory
Technical Advisory Group Chair, IEEE 802.18 SG1
(SG on License-Exempt Use of Unused TV
Spectrum) Interim Chair, IEEE 802.22 (pending)
Working Group On WRANs 4991 Shimerville
Road Emmaus, PA 18049 USA E-mail
carlstevenson_at_agere.com
carl.stevenson_at_ieee.org
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• Introduction
• The goal of this presentation is to
• Acknowledge the importance and value of TV
  broadcasting
• Show that large amounts of the TV broadcast
  allocations are unused or underused (and why)
• Examine the feasibility and benefits of
  additional uses of that unused TV spectrum
• Inform ITU-R SG8 of ongoing studies and
  standards activities aimed at additional,
  non-interfering uses of this spectrum
• Encourage regulators to consider how such
  additional , non-interfering uses can provide
  public benefit and increase the efficiency of
  spectrum utilization

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• Clearly, TV broadcasting is an important and
  valuable use of spectrum
• The value of TV broadcasting is not in question
• TV broadcasting provides many important
  benefits
• News and weather
• Entertainment
• Educational
• Cultural
• Other

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• However
• Much spectrum allocated for TV is
  unused/underused
• Particularly in sparsely populated areas, where
  few TV stations exist
• But, even in more densely populated areas, some
  channels are unused
• This is necessary to prevent interference
  between TV stations
• Co-channel separation between TV stations must
  be large
• Overlapping coverage areas would cause
  interference
• Technical limitations of TV receivers render
  other channels off-limits
• Dynamic range
• Adjacent channel rejection
• Intermodulation, etc.
• Result many TV channels are unused over
  significant geographical areas

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Example 1 Channel 5 in the Eastern US (graphic
courtesy of Shared Spectrum Co. from a
contribution to IEEE 802.18 SG1)
Grade B 50 and 90 contours
Grade B 50 and 90 contours
Grade B 50 and 90 contours
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Example 2 Channel 54 in the Eastern US (graphic
courtesy of Shared Spectrum Co. from a
contribution to IEEE 802.18 SG1)
Grade B 50 and 90 contours
Grade B 50 and 90 contours
Grade B 50 and 90 contours
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• Conclusion there is much unused or underused
  spectrum in the TV bands
• (sometimes referred to as white space)
• Could this spectrum be used for other uses,
  without causing interference to the primary
  broadcast use?
• The answer is almost certainly so
• The major issues are
• Must assure non-interference to primary TV use
• This is a fundamental requirement
• The availability of white space is highly
  variable
• Channel by channel and area by area
• Terrain variations and other factors affect
  availability
• In some areas, some TV stations are not active
  24/7
• Therefore, systems designed to use this white
  space should
• Intelligently sense environment
• Reliably and robustly determine channel
  availability
• Not transmit on channels where interference
  would result
• Be adaptable to changes in incumbent (TV) use
• Be technically and economically feasible
• Provide a valuable service to justify use of the
  spectrum

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• Can these issues be satisfactorily addressed?
• Initial studies in IEEE 802.18 SG1 show promise
• TV signals have unique spectral characteristics
• TV transmitters are powerful
• This facilitates Incumbent Profile Detection
  (IPD)
• With a limited set of incumbent signatures IPD
  is easier
• The nature of TV spectral signatures also makes
  IPD easier
• Generally high transmission power
• Known, unique spectral signatures
• TV transmissions are more continuous than
  intermittent
• TV transmitters located at fixed locations
• Applies to both analog and digital TV systems
• Cognitive Radio (CR) techniques appear to be a
  promising approach to reliable interference
  avoidance

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Example 1 Analog TV (NTSC) Spectrum(this slide
courtesy of John Notor of Cadence Design Systems,
Inc.)

• Power primarily confined to Video and Audio
  carriers.
• Distinctive double peaked spectrum makes
  identification by spectrum profiling relatively
  easy.
• Relatively high narrowband power levels compared
  to DTV.

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Example 2 Digital TV (ATSC) Spectrum(this slide
courtesy of John Notor of Cadence Design Systems,
Inc.)

• Power spread over center 5.38 MHz within a TV
  channnel.
• Pilot tone is a distinctive feature when observed
  in a narrowband receiver.
• Pilot tone power is 11.3 dB below average power
  measured in a 6 MHz bandwidth.

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Example of Co-Channel Interference Range Margin
From Initial Studies(this slide courtesy of John
Notor of Cadence Design Systems, Inc.)
Limit of CR DTV Sensing Capability
Sensing Margin 48116 km
DTV Service Area
D/U Range Margin 15.693.3 km
Edge of DTV Service Contour
CR Range to 23 dB D/U Limit
R
17.1 lt R lt 32.4 km (36 dBm EIRP)
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• Are solutions to the issues of sharing this
  unused spectrum on a strictly non-interfering
  basis economically realizable with todays
  technology?
• Studies to date indicate yes
• Ultimate solution still being defined, but key
  components appear to be
• Use of Cognitive Radio (smart radio)
  technology
• To identify channels that can be used without
  causing interference
• To adapt to changing or intermittent spectrum
  use by TV stations
• Transmitter Power Control to limit interference
  range

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• Overview of Activities in this Area in the IEEE
  802 Standards Committee
• Study group (IEEE 802.18 SG1) chartered under
  parentage of IEEE 802.18 in November 2003
• Efforts of the Study Group to date
• Evaluate candidate applications for
  standardization in terms of best and highest use
  of the spectrum
• Do preliminary studies of interference avoidance
  methods
• Prepare a Project Authorization Request (PAR)
  seeking to form a new standard development
  Working Group within IEEE 802
• Results to date
• PAR approved by Study Group, IEEE 802.18, and
  the IEEE 802 Executive Committee at the July 2004
  IEEE 802 plenary
• Pending final approval by the IEEE-SA Standards
  Board on September 23, 2004, the first meeting of
  new WG (IEEE 802.22) is anticipated to be held at
  the November 2004 IEEE 802 plenary
• In the meantime, work continues in the Study
  Group

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Abstract of the Proposed IEEE 802.22 PAR Purpose
of the PAR (note as of the time of this
presentation this PAR will not yet have gained
final approval by the IEEE-SA Standards
Board) To gain approval to start a new Working
Group to develop a new IEEE 802 Standard Proposed
title Standard for Information Technology
-Telecommunications and information exchange
between systems Wireless Regional Area Networks
(WRAN) - Specific requirements - Part 22
Cognitive Wireless RAN Medium Access Control
(MAC) and Physical Layer (PHY) specifications
Policies and procedures for operation in the TV
Bands Scope of the Project This standard
specifies the air interface, including the medium
access control layer (MAC) and physical layer
(PHY), of fixed point-to-multipoint wireless
regional area networks operating in the VHF/UHF
TV broadcast bands between 54 MHz and 862
MHz. Purpose of Proposed Project This standard
is intended to enable deployment of interoperable
802 multivendor wireless regional area network
products, to facilitate competition in broadband
access by providing alternatives to wireline
broadband access and extending the deployability
of such systems into diverse geographic areas,
including sparsely populated rural areas, while
preventing harmful interference to incumbent
licensed services in the TV broadcast
bands. Reason for the standardization
project There is a large, untapped market for
broadband wireless access in rural and other
unserved/underserved areas where wired
infrastructure cannot be economically deployed.
Products based on this standard will be able to
serve those markets and increase the efficiency
of spectrum utilization in spectrum currently
allocated to, but unused by, the TV broadcast
service.
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• Why should regulators consider alternative uses
  of unused TV broadcast spectrum?
• To promote more efficient use of the spectrum
• To enable the provision of additional services
  to the public
• One of the most compelling service candidates
  appears to be fixed broadband wireless access,
  particularly in rural and other
  unserved/underserved areas
• Favorable propagation characteristics for f lt 1
  GHz
• Lower propagation loss
• Better foliage/building penetration
• Better for NLOS links
• More capable of economically serving widely
  dispersed users than systems operating at much
  higher frequencies

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Thank you for your attention! Any questions?