LEIRP ou Le PFD

1
LEIRPouLe PFD?
Consulting on wireless technology and policy

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

ANFR 26 avril 2006
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Background

• Many concepts of spectrum regulation date to the
  early days of radio technology
• Higher frequencies and new technology may create
  new options
• Traditionally ERP and EIRP have been the
  dimension space to specify transmitter power

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Basic Spectrum Management Issues

• Cochannel issues are the most straightforward and
  have a major impact on frequency reuse
• Adjacent and nearby channels also have a real
  impact due to limitations of practical receivers
• Example In US NTSC/TV rules only 1 of 6 channels
  used in a given city due to receiver limitations

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Basic Spectrum Management Issues

• Near/far issues limit system performance and
  practical use of spectrum
• Usually addressed through
• Frequency assignment practices
• Transmitter frequency rolloff
• Receiver selectivity

F1 transmitter
F2 receiver
F2 transmitter
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Northpoint Nextel

• Two recent FCC issues with near/far at their
  roots
• Northpoint
• A proposal to use 12 GHz BSS downlink band for
  terrestrial point-to-multipoint video
  distribution
• If transmitter on north side of community, no
  interference on a clear day
• Rain impacts downlink more than terrestrial path
  and leads to near/far problems

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Northpoint Nextel

• Nextel operated mobile telephone system in 800
  MHz spectrum interleaved with land mobile public
  safety/PS users - for historical reasons
• Near/far interference near Nextel towers results
  in receiver-generated intermodulation in PS
  receivers

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csc2 Antenna Technology

• Cosecant squared antenna technology has great
  potential to reduce real practical limits to
  efficiency at UHF and above
• csc2 technology, developed at WWII MIT Radiation
  Laboratory and used in GPS, results in relatively
  uniform pfd over a large area
• Requires vertical length of 10?

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csc2 Antenna Technology

• Good design of vertical pattern of antennas can
  limit dynamic range of signals near antenna sites
• For example, UHF TV transmitters have moderate
  PFDs near antenna despite 5 MW EIRP

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csc2 Antenna Technology

• csc2 technology is practical at
• f gt 1 GHz and could be used productively in
  many applications to improve spectrum efficiency
• New computer algorithms simplify antenna
  synthesis

www.remec.com/pdfs/LMDS20ShapeBeam.pdf
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csc2 Antenna Technology

• Near/far problems are generally externalities
  and little incentive for licensees to control
  them
• Not aware of any regulations that encourage or
  require pfd control for terrestrial systems
• But satellite pfd limits exist
• Few products available at present
• Possible chicken or egg problem

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Examples of Products
2 GHz
28 GHz
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Conclusions

• csc2 antennas create some new options for
  increasing spectrum efficiency above 1 GHz
• Would ANFR like to explore issue in future ITU-R
  deliberations?