Last Friday, the FCC requested comment on the establishment of a "spectrum etiquette" for 902-928 MHz. At the same time, it turned down two petitions for reconsideration of its 2004 rule change giving more flexibility to unlicensed operations in that band, as well as 2400-2483.5 and 5725-5850 MHz.

The 2004 changes effectively increased the power available to digitally modulated systems in the 902-928 MHz band. A licensed LMS operator that shares the band asked that implementation of the rules be postponed until after the FCC conducts and completes a study on how the changes affect LMS. A meter-reading provider asked for imposition of a spectrum etiquette for newly certified devices, including a duty cycle limitation and possibly a listen-before-talk protocol, to reduce interference in the band. The FCC denied both requests.

The FCC did, however, issue a Further Notice of Proposed Rulemaking on a spectrum etiquette for 902-928 MHz. Among the issues raised:

  • whether a spectrum etiquette is needed or appropriate, noting there is presently no rule against a device occupying the entire band at 100% duty cycle, thus making it difficult for other users to gain access;
  • whether the FCC should require listen-before-talk;
  • whether higher-powered devices should have limitations on duty cycle; for example, a maximum duty cycle varying from 10% to 100% as power increases from 0 to 30 dBm;
  • whether synchronization among multiple devices should be allowed (assuming duty cycle is limited);
  • whether a given device should be able to vary power and duty cycle during operation (ditto);
  • whether an etiquette should be applied only to digitally modulated devices (as that term is used in Section 15.247), or should also apply to frequency-hoppers and other kinds of signals;
  • whether an etiquette should be made applicable to 2400-2483.5 and 5725-5850 MHz.

Comments and reply comments will be due 75 and 105 days, respectively, after publication in the Federal Register. That will probably happen in early July.

The FCC’s order and Further Notice are at this link, or ask me for a copy by return email.