Sec.  90.377   Frequencies available; maximum EIRP and antenna height, and priority
communications.

   (a) Licensees shall transmit only the power (EIRP) needed to communicate
   with an OBU within the communications zone and must take steps to limit the
   Roadside Unit (RSU) signal within the zone to the maximum extent
   practicable.

   (b) Frequencies available for assignment to eligible applicants within the
   5850–5925 MHz band for RSUs and the maximum EIRP permitted for an RSU with
   an antenna height not exceeding 6 meters above the roadway bed surface are
   specified in the table. Where two EIRP limits are given, the higher limit is
   permitted only for state or local governmental entities.


------------------------------------------------------------------------
                                 Frequency   Max. EIRP
          Channel No.           range (MHz)  \1\ (dBm)     Channel use
------------------------------------------------------------------------
170...........................    5850-5855             Reserved.
172...........................    5855-5865       33    Service Channel.
174...........................    5865-5875       33    Service Channel.
175...........................    5865-5885       23    Service Channel.
                                                         \2\
176...........................    5875-5885       33    Service Channel.
178...........................    5885-5895  33 / 44.8  Control channel.
180...........................    5895-5905       23    Service Channel.
181...........................    5895-5915       23    Service Channel.
                                                         \2\
182...........................    5905-5915       23    Service Channel.
184...........................    5915-5925  33 / 40    Service Channel.
------------------------------------------------------------------------
\1\ An RSU may employ an antenna with a height exceeding 6 meters but
  not exceeding 15 meters provided the EIRP specified in the table above
  is reduced by a factor of 20 log(Ht/6) in dB where Ht is the height of
  the radiation center of the antenna in meters above the roadway bed
  surface. The EIRP is measured as the maximum EIRP toward the horizon
  or horizontal, whichever is greater, of the gain associated with the
  main or center of the transmission beam. The RSU antenna height shall
  not exceed 15 meters above the roadway bed surface.
\2\ Channel Nos. 174/176 may be combined to create a twenty megahertz
  channel, designated Channel No. 175. Channels 180/182 may be combined
  to create a twenty-megahertz channel, designated Channel No. 181.

   (c) Except as provided in paragraphs (d) and (e) of this section,
   non-reserve DSRCS channels are available on a shared basis only for use in
   accordance with the Commission's Rules. All licensees shall cooperate in the
   selection and use of channels in order to reduce interference. This includes
   monitoring for communications in progress and any other measures as may be
   necessary to minimize interference. Licensees of RSUs suffering or causing
   harmful interference within a communications zone are expected to cooperate
   and resolve this problem by mutually satisfactory arrangements. If the
   licensees are unable to do so, the Commission may impose restrictions
   including specifying the transmitter power, antenna height and direction,
   additional filtering, or area or hours of operation of the stations
   concerned. Further the use of any channel at a given geographical location
   may be denied when, in the judgment of the Commission, its use at that
   location is not in the public interest; the use of any channel may be
   restricted as to specified geographical areas, maximum power, or such other
   operating conditions, contained in this part or in the station
   authorization.

   (d) Safety/public safety priority. The following access priority governs all
   DSRCS operations:

   (1) communications involving the safety of life have access priority over
   all other DSRCS communications;

   (2) subject to a Control Channel priority system management strategy (see
   ASTM E2213–03 DSRC Standard at  Sec. 4.1.1.2(4)) DSRCS communications involving
   public safety have access priority over all other DSRC communications not
   listed in paragraph (d)(1) of this section. Roadside Units (RSUs) operated
   by state or local governmental entities are presumptively engaged in public
   safety priority communications.

   (e) Non-priority communications. DSRCS communications not listed in
   paragraph (d) of this section are non-priority communications. If a dispute
   arises concerning non-priority communications, the licensee of the
   later-registered RSU must accommodate the operation of the early registered
   RSU, i.e., interference protection rights are date-sensitive, based on the
   date that the RSU is first registered (see  Sec. 90.375) and the later registered
   RSU must modify its operations to resolve the dispute in accordance with
   paragraph (f) of this section.

   (f) Except as otherwise provided in the ASTM-DSRC Standard, as incorporated
   by reference pursuant to 5 U.S.C. 552(a) and 1 CFR part 51 and approved by
   the Director of the Federal Register, copies may be inspected at the Federal
   Communications Commission, 445 12th Street, SW, Washington, DC 20554 or
   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. Copies of the ASTM E2213–03 DSRC Standard can be obtained from
   ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
   PA 19428–2959. Copies may also be obtained from ASTM via the Internet at
   http://www.astm.org. Except as provided in the ASTM-DSRC Standard for the
   purposes of paragraph (e) of this section objectionable interference will be
   considered to exist when the Commission receives a complaint and the
   difference in signal strength between the earlier-registered RSU and the
   later-registered RSU (anywhere within the earlier-registered RSU's
   communication zone) is 18 dB or less (co-channel). Later-registered RSUs
   causing objectionable interference must correct the interference immediately
   unless written consent is obtained from the licensee of the
   earlier-registered RSU.

   [ 69 FR 46444 , Aug. 3, 2004]