FCC Says Relaxed 2.5 GHz OOBE Limits Won't Cause BAS Interference

In the Fifth Report and Order in proceeding FCC 14-76, which amended rules to facilitate fixed and mobile broadband access, educational and other advanced services in the 2150-2162 and 2500-2690 MHz bands, the FCC relaxed out-of-band emission (OOBE) limits for broadband mobile devices using the 2.5 GHz band.

The decision to retain existing OOBE limits at and below 2496 MHz for all Broadband Radio System (BRS) and Educational Broadband System (EBS) channels satisfied earlier objections by Globalstar. The R&O stated that: "[It] would also address EIBASS' [Engineers for the Integrity of Broadcast Auxiliary Service Spectrum] concerns about increased interference to BAS Channel A9 (2467-2483.5 MHz "

While several parties objected to the stricter OOBE limits, the R&O made a case for this, stating that the revised limits would allow licensees to provide enhanced broadband services to subscribers by operating with wider channels over most of the 2.5 GHz band.

The R&O noted that EIBASS had also expressed concern about increased interference to BAS Channel A10 (2483.5-2500 MHz), stating "With respect to the 2491-2500 MHz portion of that channel, that portion could, in theory, be subject to increased interference from certain adjacent channel BRS/EBS mobile units’ increased OOBE. However, we believe the chance of harmful interference to BAS Channel A10 is very low for several reasons."

In making this statement, the FCC observed that BAS Channel A10 was currently "subject to OOBE from BRS/EBS base stations, which can operate at higher power than mobile units."

Further, the FCC was unaware of any allegation or complaints about BRS/EBS operations causing interference to BAS Channel A10 operations. It also observed that there are "many fewer operations on BAS Channel A10 (56 active licenses) than on any other BAS channel, and BRS/EBS mobile stations are unlikely to be operated in close proximity to BAS receiving antennas, which are typically located on the same or similar structures as TV broadcasting antennas."

Finally, the commission noted that the primary use of the 2.5 GHz band was for TDD operations, and believed that BRS/EBS operators are unlikely to use channels at or near the lower edge of the 2.5 GHz band in situations where base stations may cause harmful interference to BAS or MSS operations.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.