§ 25.254   Special requirements for ancillary terrestrial components operating
in the 1610-1626.5 MHz/2483.5-2500 MHz bands.

   (a) An applicant for an ancillary terrestrial component in these bands must
   demonstrate that ATC base stations shall:

   (1) Not exceed a peak EIRP of 32 dBW in 1.25 MHz;

   (2) Not cause unacceptable interference to systems identified in paragraph
   (c)  of this section and, in any case, shall not exceed out-of-channel
   emissions of −44.1 dBW/30 kHz at the edge of the MSS licensee's authorized
   frequency assignment;

   (3)  At the time of application, that it has taken, or will take steps
   necessary to avoid causing interference to other services sharing the use of
   the 2450-2500 MHz band through frequency coordination; and

   (4)  Base stations operating in frequencies above 2483.5 MHz shall not
   generate EIRP density, averaged over any two-millisecond active transmission
   interval, greater than −70 dBW/MHz in the 1559-1610 MHz band. The EIRP,
   averaged over any two-millisecond active transmission interval, of discrete
   out-of-band emissions of less than 700 Hz bandwidth from such base stations
   shall not exceed −80 dBW in the 1559-1610 MHz band. A root-mean-square
   detector function with a resolution bandwidth of one megahertz or equivalent
   and no less video bandwidth shall be used to measure wideband EIRP density
   for purposes of this rule, and narrowband EIRP shall be measured with a
   root-mean-square  detector function with a resolution bandwidth of one
   kilohertz or equivalent.

   (b) An applicant for an ancillary terrestrial component in these bands must
   demonstrate that mobile terminals shall:

   (1) Meet the requirements contained in § 25.213 to protect radio astronomy
   service (RAS) observations in the 1610.6-1613.8 MHz band from unacceptable
   interference;

   (2) Observe a peak EIRP limit of 1.0 dBW in 1.25 MHz;

   (3) Observe an out-of-channel EIRP limit of −57.1 dBW/30 kHz at the edge of
   the licensed MSS frequency assignment.

   (4)  ATC  mobile  terminals  operating  in assigned frequencies in the
   1610-1626.5 MHz band shall not generate EIRP density, averaged over any
   two-millisecond active transmission interval, greater than -70 dBW/MHz in
   the  1559-1605  MHz  band or greater than a level determined by linear
   interpolation in the 1605-1610 MHz band, from −70 dBW/MHz at 1605 MHz to −10
   dBW/MHz at 1610 MHz. The EIRP, averaged over any two-millisecond active
   transmission interval, of discrete out-of-band emissions of less than 700 Hz
   bandwidth  from  such mobile terminals shall not exceed −80 dBW in the
   1559-1605 MHz band or exceed a level determined by linear interpolation in
   the 1605-1610 MHz band, from −80 dBW at 1605 MHz to −20 dBW at 1610 MHz. The
   EIRP density of carrier-off-state emissions from such mobile terminals shall
   not  exceed  −80  dBW/MHz  in  the 1559-1610 MHz band, averaged over a
   two-millisecond  interval. A root-mean-square detector function with a
   resolution  bandwidth of one megahertz or equivalent and no less video
   bandwidth shall be used to measure wideband EIRP density for purposes of
   this rule, and narrowband EIRP shall be measured with a root-mean-square
   detector  function  with  a  resolution  bandwidth of one kilohertz or
   equivalent.

   (c)  Applicants  for  an ancillary terrestrial component to be used in
   conjunction with a Mobile-Satellite Service system using CDMA technology
   shall  coordinate  the use of the 1.6/2.4 GHz Mobile-Satellite Service
   spectrum designated for CDMA systems using the framework established by the
   ITU  in  Recommendation ITU-R M.1186 “Technical Considerations for the
   Coordination Between Mobile Satellite Service (MSS) Networks Utilizing Code
   Division Multiple Access (CDMA) and Other Spread Spectrum Techniques in the
   1-3  GHz  Band” (1995). Recommendation ITU-R M.1186 is incorporated by
   reference. The Director of the Federal Register approves this incorporation
   by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of
   this standard can be inspected at the Federal Communications Commission, 445
   12th Street, SW., Washington, DC (Reference Information Center) or at the
   National Archives and Records Administration (NARA). For information on the
   availability  of  this  material at NARA, call 202-741-6030, or go to:
   http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_loc
   ations.html.  The ITU-R Recommendations can also be purchased from the
   International Telecommunication Union (ITU), Place des Nations, CH-1211
   Geneva 20, Switzerland.

   (d) To avoid interference to an adjacent channel licensee in the Broadband
   Radio Service (BRS), the power of any ATC base station emission above 2495
   MHz shall be attenuated below the transmitter power (P) measured in watts in
   accordance with the standards below. If these measures do not resolve a
   documented interference complaint received from the adjacent channel BRS
   licensee, the provisions of § 25.255 shall apply.

   (1) For base stations, the attenuation shall be not less than 43 + 10 log
   (P) dB at the upper edge of the authorized ATC band, unless a documented
   interference complaint is received from an adjacent channel licensee in the
   BRS. Provided that a documented interference complaint cannot be mutually
   resolved  between  the  parties,  the following additional attenuation
   requirements set forth in subsections (2)-(5) shall apply:

   (2) If a pre-existing BRS base station suffers harmful interference from
   emissions caused by a new or modified ATC base station located 1.5 km or
   more away, within 24 hours of the receipt of a documented interference
   complaint the ATC licensee must attenuate its emissions by at least 67 + 10
   log (P) dB measured at 3 megahertz above the edge of the authorized ATC
   band,  and  shall  immediately  notify  the  complaining licensee upon
   implementation of the additional attenuation.

   (3) If a pre-existing BRS base station suffers harmful interference from
   emissions caused by a new or modified ATC base station located less than 1.5
   km  away,  within 24 hours of the receipt of a documented interference
   complaint the ATC licensee must attenuate its emissions by at least 67 + 10
   log (P) −20 log(Dkm/1.5) dB measured at 3 megahertz above the edge of the
   authorized ATC band, or if both base stations are co-located, limit its
   undesired signal level at the pre-existing BRS base station receiver(s) to
   no  more than −107 dBm measured in a 5.5 megahertz bandwidth and shall
   immediately notify the complaining licensee upon such reduction in the
   undesired signal level.

   (4) If a new or modified BRS base station suffers harmful interference from
   emissions caused by a pre-existing ATC base station located 1.5 km or more
   away, within 60 days of receipt of a documented interference complaint the
   licensee of the ATC base station must attenuate its base station emissions
   by at least 67 + 10 log (P) dB measured at 3 megahertz above the edge of the
   authorized ATC band.

   (5) If a new or modified BRS base station suffers harmful interference from
   emissions caused by a pre-existing ATC base station located less than 1.5 km
   away, within 60 days of receipt of a documented interference complaint:

   (i) the ATC licensee must attenuate its base station emissions by at least
   67 + 10 log (P) −20 log(Dkm/1.5) dB measured 3 megahertz above the edge of
   the authorized ATC band, or

   (ii) if both base stations are co-located, the ATC licensee must limit its
   undesired signal level at the new or modified BRS base station receiver(s)
   to no more than −107 dBm measured in a 5.5 megahertz bandwidth.

   (6)  Compliance  with  these  rules is based on the use of measurement
   instrumentation  employing a resolution bandwidth of 1 MHz or greater.
   However, in the 1 MHz bands immediately above and adjacent to the 2495 MHz a
   resolution bandwidth of at least one percent of the emission bandwidth of
   the fundamental emission of the transmitter may be employed. A narrower
   resolution  bandwidth is permitted in all cases to improve measurement
   accuracy, provided the measured power is integrated over the full required
   measurement bandwidth (i.e., 1 MHz or 1 percent of emission bandwidth, as
   specified). The emission bandwidth is defined as the width of the signal
   between two points, one below the carrier center frequency and one above the
   carrier center frequency, outside of which all emissions are attenuated at
   least 26 dB below the transmitter power. When an emission outside of the
   authorized bandwidth causes harmful interference, the Commission may, at its
   discretion, require greater attenuation than specified in this section.

   Note to § 25.254: The preceding rules of § 25.254 are based on cdma2000 and
   IS-95 system architecture. To the extent that a 1.6/2.4 GHz Mobile-Satellite
   Service licensee is able to demonstrate that the use of different system
   architectures would produce no greater potential interference than would be
   produced as a result of implementing the rules of this section, the licensee
   may apply for ATC authorization based on another system architecture.

   [ 68 FR 33653 , June 5, 2003, as amended at  69 FR 18803 , Apr. 9, 2004;  70 FR 19320 , Apr. 13, 2005;  73 FR 25592 , May 5, 2008;  78 FR 8430 , Feb. 6, 2013]

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