PFD Limits Becoming Centerpiece of Spectrum Frontiers Fight as Satellite Lobbying Continues
The debate over 5G and fixed satellite service sharing of the 28 GHz band increasingly involves power flux density (PFD) and proposed limits on that measure of signal power level at the receiver. "As long as you will be sharing spectrum between satellite and terrestrial systems, this is the issue," Farooq Khan, CEO of 5G technology company Phazr, told us. "The back and forth over precise technical limits on power is entirely normal," satellite industry consultant Tim Farrar told us in an email, pointing to such issues as the Globalstar/Wi-Fi in 5 GHz or the GPS industry's past challenges to Ligado. "I'd expect the FCC to be leaning in favor of terrestrial interests because that is the political priority."
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Numerous parties in the FCC spectrum frontiers proceeding have argued back and forth about PFD limits in recent days. The satellite industry has pointed to PFD limits as a route for ensuring new 28 GHz earth stations don't interfere with UMFU operations. Inmarsat in a filing Friday in docket 14-177 said it backed Satellite Industry Association and O3b arguments against defining a protection zone by specific radius and instead opting for PFD limits in relation to population-weighted density of an area.
Boeing has pushed for relaxed PFD standards for satellite downlinks operating in the 37.5-40 GHz band so as to line up with ITU standards (see 1607060046), calling the 12 dB tighter U.S. limit an "outdated restriction" that doesn't reflect more current millimeter wave technology for spectrum sharing. Terrestrial stations in the 37/39 GHz band already have interference protection from the ITU PFD limits on satellites, and the main issue in those bands is protecting satellite receiving earth stations from terrestrial interference, Lockheed Martin told staffers for Commissioners Ajit Pai and Mignon Clyburn, said ex parte filings Friday (see here and here).
The idea of relaxed PFD standards has some opponents tensing up. The National Spectrum Management Association said in a filing any such moves have to be preceded first by study and trials. Phazr, meanwhile, is pushing for stronger PFD limits to protect 5G. FCC current PFD standards don't go far enough in protecting 5G systems at larger angles of arrival and need revising, Phazr said.
Such a 12 dB increase would lead to greater satellite interference at 5G base and mobile stations, wireless spectrum licensee Straight Path said. Realistically, Straight Path said, 5G and Boeing can't "fully utilize the entire V-band in a way desired by both" and instead mobile operations should be primary concern in the 37.5-40 GHz section of the band, while satellite is favored in the 40-42 GHz swath. T-Mobile suggested adding 40-42 GHz to the spectrum frontiers order. And Khan similarly said the 40-42 GHz band would be appropriate for satellite, since the lack of sharing there now with terrestrial would let satellite operators use high power levels.
In a series of meetings with agency staff and representatives of the four regular commissioners, Straight Path wrote that it said that while satellite uplinks in 28 GHz affect only nearby 5G stations, satellite 37/39 GHz downlinks "could interfere with every 5G station in the band across the nation." The company said PFD limits in 37.6-40 GHz band shouldn't be increased, though they could be considered in the 37-37.6 and the 40-42 GHz bands.
Meanwhile, satellite industry lobbying on sharing of the 28 GHz band with 5G operations has been heavy in recent days, according to numerous filings posted Friday in docket 14-177. The Satellite Industry Association, recapping a meeting it had with Brendan Carr of Commissioner Ajit Pai's office, said it went over its arguments for satellite services having co-primary status in the band, for aggregate interference issues being addressed with actual constraints on upper microwave flexible use (UMFU) operations, for allowing "robust deployment" of earth stations in the 37/39 GHz band and for grandfathering of protections for 28 GHz earth station applications pending before the effective date of any FCC order. SIA said at the meeting were representatives of O3b, Lockheed Martin, Iridium, AT&T's DirecTV, EchoStar, Inmarsat, ViaSat, Intelsat and Boeing.
Lockheed Martin said (see here and here) it met with Carr and separately with Commissioner Mignon Clyburn aide Daudeline Meme about its arguments (see 1606240026) that any FCC action in the 28 GHz band needs conditions on aggregate interference. EchoStar Senior Vice President-Regulatory Affairs Jennifer Manner met with Chairman Tom Wheeler aide Edward Smith and separately with representatives of the other four commissioners (see here, here, here, here and here) to say more than one earth station location likely could be deployed in each UMFU license area as long as the population impact benchmark wasn't exceeded, but the FCC should seek additional comment. EchoStar also said there should be reconciliation between the earth station siting limits for the 28 GHz band and 38 GHz band, instead of the FCC's current approach of the former being one per county and the latter being one per partial economic area. Since future broadband satellites probably will operate with gateway earth stations in both bands, being able to collocate those earth stations would be more efficient, EchoStar said.
O3b CEO Steve Collar met with staffers of the four regular commissioners to push for "a reasonable sharing regime ... that is not unduly constraining on UMFU operations" and said fixed satellite service satellites in the 28 GHz band should be protected from skyward UMFU emissions. O3b said that it needs grandfathering for existing and applied-for earth stations, "reasonable access" to building new earth stations and that rather than a one-site-per-county limit, the agency should allow access to spots that meet criteria for effective earth station performance.
And more satellite operators joined those backing ViaSat's spectrum frontiers arguments (see 1607070046). Intelsat and Telesat Canada said ViaSat "accurately rebuts the claim" mobile wireless poses no interference threat to satellite receivers in the 28 GHz band. They also said the commission at least needs to ensure satellite receiver protection from co-channel and aggregate interference.