Last year the FCC issued a Notice of Proposed Rulemaking (NPRM) regarding the “Terrestrial Low-Power Service” (TLPS) and Advanced Wireless Service Band 5 (AWS-5) proposed by Globalstar, Inc. that would include operation on BAS 2 GHz channel A10 (2483.5 – 2500 MHz). See my articles Globalstar Proposal Could Impact 2 GHz ENG Channels and FCC Seeks Comments on Globalstar Use of 2.4 GHz ENG Channels for information on Globalstar's proposals.
Late last month Engineers for the Integrity of Broadcast Auxiliary Service Spectrum (EIBASS) submitted ex parte comments in response to the reply comments of two parties in the NPRM proceeding. EIBASS took issue with comments from Samuelson-Glushko Technology Law & Policy Clinic (S-G_TLPC) that recognized broadcasters’ concern about Globalstar's proposed use of the BAS spectrum but concluded “Moreover, BAS operates primarily below 2483.5 MHz and already successfully coexists with Wi-Fi.”
“S-G_TLPC is misinformed,” EIBASS said. “As was documented in the January 14, 2013, EIBASS filing to RM-11685 (the predecessor rulemaking to IB Docket 13-213), the existence of Wi-Fi emissions at 2,450–2,483.5 MHz have so chronically raised the noise floor on TV BAS Channels A8 (2,450–2,467 MHz) and A9 (2,467–2,483.5 MHz) as to make those 2.5 GHz TV BAS channels far less desirable than the 2 GHz TV BAS channels (i.e., A1 through A7, at 2,025–2,110 MHz). Indeed, in some areas, effectively unusable.” A spectrum analyzer plot showed an 8 dB worse noise floor for A8 and A9 versus A10 in the Phoenix area.
In its Reply Comments, S-G_TLPC stated, “BAS and unlicensed users have expressed only speculative claims about the effect of TLPS on their systems” and "no commenter has proven any demonstrable harm.” EIBASS points to its previous filings regarding terrestrial use of the 2483.5-2495 MHz MSS spectrum for terrestrial wireless communications. In its Docket 10-142 filing, EIBASS documented interference from S-band ATC [Ancillary Terrestrial Component] to grandfathered TV BAS Channel A10 operations in both Chicago and Sacramento. Using data contained in the FCC case report on the Chicago interference, EIBASS determined “It would take just 250 TLPS/AWS-5 Wi-Fi units simultaneously transmitting in the same area to cause similar interference.” EIBASS concludes “Thus, S-G_TLPC is simply mistaken in its characterization that S-Band MSS ATC interference to TV BAS is 'speculative' and that 'no commenter has proven any demonstrable harm.'”
EIBASS referenced filings that showed the infeasibility of sharing spectrum with co-channel TV BAS Channel A10 TV Pickup stations. “Given the unscheduled nature of electronic news gathering (ENG) use, frequency sharing is not practical for the same reason you don't park in fire station driveways, or in front of fire hydrants: You don't know when the space (or spectrum) will be needed, so you have to keep it clear.”
TV BAS Channel A10 isn't used in all parts of the country. EIBASS states, “Just like was the case for only allowing FS stations use of the 7 or 13 GHz TV BAS bands if the FS path would be outside the operational area of all TV Pickup stations, this would still leave substantial portions of the county where no grandfathered A10 operations existed. EIBASS has no objection to AWS-5 use in those areas.”
The EIBASS ex parte filing has additional details, including a map showing the operational areas of grandfathered TV BAS Channel A10 TV Pickup station and an example the of “Fundamentally Incompatible Sharing” referenced in the filing.
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.
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