Commercial Mobile Radio Services

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Commercial Mobile Radio Services Radio Astronomy

• Andrew CleggNational Science Foundation

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CMRS

• CMRS Commercial Mobile Radio Service
• Generally speaking, it is the connection of
  mobile radio devices to the public switched
  telephone network for the provision of wireless
  telephony
• Better know as cellular, PCS, and Nextel (ESMR)
• Latest incarnation is AWS (Advanced Wireless
  Services)
• CMRS is governed under various provisions of the
  FCC rules
• Cellular Part 22 (Cellular)
• PCS Part 24 (Personal Communications Service)
• ESMR Part 90 (Private Land Mobile)
• AWS Part 27 (Wireless Communications Service)

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CMRS Air Interfaces

• Analog. 30 kHz channels, FM. Required by analog
  set-aside rules, sunsetting in 2006. Will
  disappear quickly after that.
• TDMA (aka ANSI-136). Digital three voice
  channels time-multiplexed onto each 30 kHz
  carrier being phased out.
• GSM. Digital 8 time slots per 200 kHz carrier
  (either 7 voice 1 control or 8 voice)
  frequency hopping (except control channel, BCCH)
  GMSK modulation power control
• iDEN. GSM backbone on 25 kHz digital carrier.
  Proprietary to Motorola.
• CDMA (aka ANSI-95). Spread spectrum code division
  access on single 1.25 MHz digital carrier tight
  power control lower PSD than other interfaces
• EDGE. 2.5G 8-PSK version of GSM provides
  higher data rates slightly higher OOBE than GSM
• CDMA-2000 and WCDMA 3G versions of CDMA higher
  chip rate 3 5 MHz bandwidth carriers. Most all
  providers will evolve to one or the other.

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Present CMRS Bands
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Current CMRS Issues Relevant to Radio Astronomy

• 700 MHz
• 2nd harmonic impacts to 1420 MHz
• New allocations at 1710 1755 / 2110 2155 MHz
• Affect on 1720 MHz OH line
• Review of cellular rules governing operation on
  aircraft
• Potential new interference concern

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700 MHz

• DTV transition requires TV stations to vacate
  channels 52 69 and move all operations to core
  channels 2 51
• Channels 52 69 will be re-allocated to generic
  Fixed and Mobile services
• Upper 700 (old channels 60 69) will accommodate
  public safety and commercial services
• Lower 700 (old 52 59) will be commercial only,
  perhaps eventually CMRS
• Transition plan is complex
• Upper 700 channels must be vacated by Dec 31,
  2006
• Lower 700 will be a temporary parking space for
  analog and DTV stations after the upper 700
  channels are vacated and until the DTV transition
  to the core channels is complete

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Lower 700 Service Rules

• Fixed or Mobile
• Flexible allocation
• Base station ERP limit 50 kW
• Mobile station ERP limit 30 W
• Portable station ERP 3 W
• OOBE limit 13 dBm/100 kHz -93 dB(W/Hz)for
  all station classes
• Applies to harmonic emissions
• Requires 187 dB propagation loss to meet Rec 769
  levels -255 dB(W/m2/Hz) _at_ 1400 MHz

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Lower 700 Auctions

• Lower 700 A, B, and E block auction not yet
  scheduled
• Lower 700 C D block auction occurred mid-2003
• Generated 58M in revenue
• Qualcomm acquired essentially nationwide coverage
  of D block (unpaired 6 MHz) for 38M
• Qualcomm plans to use D block to provide
  ubiquitous streaming video service as an adjunct
  to CDMA-2000 and WCDMA networks
• Service will be provided from high power
  super-cells blanketing the country (50 kW ERP
  allowed)
• 2nd harmonic of D block is 1432 1444 MHz

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Lower 700 Forecast

• Lower 700 includes sub-harmonic of 1400 1427
  RAS allocation
• Complex DTV transition necessitates scrutiny of
  channel assignments during transition
• 2nd harmonic emissions from TV stations are
  allowed to be up to8 W (-60 dBc)
• Lower 700 will probably eventually be a CMRS
  band, but near- and mid-term uncertainties
  regarding the timescale for availability of this
  band make it unfavorable for generic CMRS at this
  time
• Qualcomm service may become another problem for
  wide-band 21 cm observations
• Eventual ubiquity of portable, mobile, and base
  station devices using this band, each emitting
  harmonics up to 13 dBm/100 kHz, could be an
  interference concern for 1400 1427 MHz

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1710 1755 2110 2155 MHz

• Re-allocation of 1710 1755 MHz (from Federal
  government, mostly DoD) and 2110 2155 MHz
  (mostly fixed service) by FCC and NTIA
• Allocation is to Advanced Wireless Services
  through generic and flexible Fixed and Mobile
  primary allocations
• Bands are paired for duplex operation
• Lower band includes 1720 MHz OH line
• US311 provides for radio astronomy on an
  unprotected basis in the band 1718.8 1722.2 MHz
  at radio astronomy sites
• Prior use of this band by DoD was fairly
  localized
• Most service providers will use this band to
  expand 2G capacity and/or deploy 3G technologies
• This band is eagerly sought by providers and will
  be put to use quickly and heavily
• Biggest factor in deployment schedule will be
  clearing of legacy systems, expected by December
  31, 2008

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1710 1755 2110 2155 MHzService Rules

• AWS in this band is under Part 27 (WCS)
• Geographic licenses
• Band Plan
• Block Pairings Amount Area Licenses
• A 1710-1720 and 2110-2120 2x10 EA 176
• B 1720-1730 and 2120-2130 2x10 REAG 12
• C 1730-1735 and 2130-2135 2x5 REAG 12
• D 1735-1740 and 2135-2140 2x5 RSA/MSA 734
• E 1740-1755 and 2140-2155 2x15 REAG 12
• Power Limits
• Fixed/Base in 2110 2155 100 W Tx/1640 W EIRP
• Fixed/Mobile/Portable in 1710 1755 1W EIRP
• OOBE -13 dBm/MHz
• Auction presently anticipated as early as June
  2006

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Aeronautical Use of CMRS

• FCC rules specifically prohibit the use of
  cellular phones aboard aircraft (47 CFR 22.925)
• Not an FAA rule
• Applies to commercial and general aviation
• Rule is based upon interference concerns
• PCS phones are not specifically prohibited
• Most airlines prohibit use of any type of mobile
  phone aboard their aircraft by policy (except
  their own air-ground and satellite phones)
  because of interference concerns to aircraft
  electronic equipment

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Aeronautical Use of CMRSRecent FCC Activity

• On December 15, Commission voted to re-examine
  its prohibition against the use of cellular
  phones on aircraft
• By extension, this will open the window for the
  use of PCS, ESMR, AWS, 3G, 4G, etc., phones
  aboard aircraft
• NPRM is expected this month (docket WT 04-435)

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Aeronautical Use of CMRSHow Would it Work?

• Implementation most likely will not be direct
  phone-to-ground service
• Inefficient
• Possible interference to aircraft electronics
• Interference to CMRS networks
• No specific plans have been made, but one
  possible scenario
• Picocells aboard aircraftonly very low base and
  mobile power levels
• Customer handsets powered down to lowest power
  class levels, and communicate only back-and-forth
  to the on-board picocell
• Backhaul possibly provided in existing
  air-to-ground allocations (849 851 894 896
  MHz) or other spectrum
• First tests using CDMA already completed

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Aeronautical Use of CMRSEstimate of
Interference Levels on Ground

• Assume lowest power class defined for GSM
  BTS/mobile stations (0 dBm per GSM 05.05 spec)
• Assume 20 dB average attenuation of signals
  propagated outside of the plane
• Assume average slant-range path of 5 miles
• Assume average number of visible planes 10
• Assume average number of users per GSM carrier
  aboard plane 7 (fully loaded GSM BCCH channel)
• Assume noise-equivalent bandwidth of 200 kHz
• Expected spectral power flux density on ground
• -30 dBW 20 dB 89 dBm2 10 dB 53 dBHz
  -182 dB(W/m2/Hz) Rec 769 (spectral line) 55
  dB _at_ 1665 MHz
• Single aircraft at 100 mile slant range exceeds
  Rec 769 by 19 dB
• For harmonic and out-of-band emissions (-13
  dBm/MHz), Rec 769 level is exceeded by 44 dB for
  users 7 (real OOBE much better though)

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SUMMARY

• Increased use of CMRS, coupled with expansion of
  frequency bands allocated to CMRS and flexibility
  of new wireless service rules, will increase the
  coordination challenges for radio astronomy in
  the 2 10 year time frame.
• Musical chairs with TV channel allotments should
  be followed closely to monitor assignment of
  channels 52 54