UNMANNED AIRCRAFT CONTROL AND COMMUNICATIONS THE SPECTRUM CHALLENGE

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UNMANNED AIRCRAFT CONTROL AND COMMUNICATIONSTHE
SPECTRUM CHALLENGE
Predator A
ERMP
Predator B
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The Spectrum Challenge

• What spectrum will be used for UAS Control and
  Communications Datalink?
• No spectrum is currently assigned for civil UAS
  control and communications.
• Identify potential spectrum.
• Choose best spectrum from technical perspective.
• Work with FAA, DoD, FCC, NTIA, ITU and World
  Radio Conference to obtain spectrum allocation.
• How much spectrum is required?
• Perform bandwidth assessment.

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The Spectrum Challenge

• Identify Potential Spectrum
• Because the Control and Communications Links are
  critical to the safe operation of the UA in the
  NAS they must operate in an RF environment that
  can be accurately quantified.
• Any interference from unexpected sources could
  lead to critical failures of the Control and
  Communications Links.
• This leads to the desire to use spectrum that has
  a specified and limited number of current users
  that will be compatible with UAS operations and
  that UAS operations will not adversely affect.

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The Spectrum Challenge

• Identify Potential Spectrum
• Spectrum allocated to current aeronautical safety
  services.
• E.g. 960-1215MHz Aeronautical Radio Navigation
  Band.
• Spectrum allocated for use by DoD.
• E.g. 1435-1525MHz Mobile Aeronautical Telemetry
  Band.
• Spectrum that can be reallocated for use by UA.
• E.g. Assign some Inmarsat or Iridium L Band
  Satellite channels to UA.
• Spectrum that uses RF waveforms that are more
  immune to interference.
• E.g. Spread spectrum in the 2.4GHz Band.

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The Spectrum Challenge

• Choose best spectrum from technical perspective.
• Must support required bandwidth.
• Must provide adequate link performance at
  required ranges without requiring large, heavy or
  power consumptive equipment.
• Must be tolerant of adverse atmospheric
  environment.
• Frequencies between 100MHz and 2GHz are
  appealing.
• Technology is not too expensive at these
  frequencies.
• These frequencies are heavily used already.

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The Spectrum Challenge

• How much spectrum is required?
• Assumed a 2030 time frame.
• Peak Instantaneous Aircraft Counts were estimated
  at 10 of manned aircraft projections.
• ICAO/FAA/EUROCONTROL Communications Operating
  Concept and Requirements (COCR) model used to
  define service volumes.
• Manned aircraft ATC communication capacity
  projections were used for voice relay bandwidth.
• Spectrum assessment did not include Sense and
  Avoid Bandwidth or Payload Return Link Bandwidth.

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The Spectrum Challenge

• How much spectrum is required?
• Used the STANAG 4586 messaging protocol.
• Used representative modulation and error
  correction.
• Used a frequency reuse architecture consistent
  with sectorized and layered NAS.
• The result estimates 5-15MHz of spectrum is
  required.

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The Spectrum Challenge

• Work with FAA, DoD, FCC, NTIA, ITU and World
  Radio Conference to obtain spectrum allocation.
• It may be possible to reassign spectrum locally
  within the US .
• Otherwise work with US representatives to ITU to
  obtain reassignment for UAS operations.
• This can take many years.
• World Radio Conference 2007 has agenda items
  aimed at obtaining spectrum that might be used
  for UAS.
• WRC 2007 also has an agenda item to discuss
  adding specific UAS spectrum discussions to the
  agenda for WRC 2010/11.