§  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 Big LEO MSS 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/ib
   r_locations.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(D[km]/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(D[km]/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 Big LEO MSS
   licensee is able to demonstrate that the use of different system
   architectures would produce no greater potential interference than that
   produced as a result of implementing the rules of this section, an MSS
   licensee is permitted to 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]