Ligado Sees Weather Spectrum Concerns Likely at Forefront in LTE PN
Ligado expects to hear feedback from the weather community seeking FCC protection from interference in the spectrum used by the National Oceanic and Atmospheric Administration (NOAA), and support from the wireless industry for its terrestrial LTE plans, but not as much from major GPS companies. That is now that the FCC has opened the door to comments on its proposed modifications to those LTE plans, one company representative told us Monday. Whether the pair of public notices issued Friday lead to the FCC's taking action this year is impossible to say, the representative said.
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With the notices, the agency is seeking comment on Ligado's proposed license application that would have it abandon any planned 1545-1555 MHz terrestrial downlink use and on its call for the FCC to initiate a rulemaking to allow for shared use of the 1675-1680 MHz band currently employed by NOAA (see here and here). Ligado and others pushed for such PNs in the months since it signed agreements with GPS companies Deere, Garmin and Trimble for Ligado to modify its terrestrial wireless plans to address GPS interference concerns (see 1604040034, 1602120052 and 1602040015).
In the license modification PN, the FCC said it particularly is seeking comments about how well the operational parameters would address GPS interference worries, particularly its plans to abandon terrestrial use of 1545-1555 MHz (see 1512090024) and whether they "effectively resolve" GPS interference concerns. The agency also is seeking comment on whether there remain "unresolved concerns" of GPS interference for Ligado's LTE plan. The agency said Ligado's current plan would leave roughly 20 MHz of frequency separation between GPS operations in the 1560-1591 MHz range and Ligado operations below 1536 MHz, and 35 MHz between GPS receivers operating above 1627.5 MHz.
If there are still GPS interference issues, the FCC said, comments should give some basis for those worries and what would address them, such as frequency offsets, power limits or more out-of-band emission limits. Comments also should provide technical information about affected GPS receivers, including details on impacts to their performance or functioning, such as loss of tracking or specific effects on location and timing accuracy. That focus on specifics is what Ligado was hoping for, indicating the proceeding is past the time for generalized complaints, the company representative told us. Comments and petitions to deny in docket 12-340 are due May 23, oppositions June 6 and replies June 16.
On Ligado's planned sharing of 1675-1680 MHz band, the FCC said it's seeking comment on studies and filings Ligado submitted in 2014 and 2015 about such sharing and about setting up terrestrial service rules for that shared use. Questions in the PN include whether those studies identified the policy and technical issues that could need addressing, the means for doing so if the agency were to act and whether Ligado's submissions singled out "appropriate types of mitigations" to protect meteorological ground stations from interference.
The agency also said it wants input on how Ligado's LTE service might affect nonfederal entities, "particularly those engaged in state and local emergency management functions or in support of land, air and sea transportation operations," plus the feasibility of their getting Geostationary Operational Environmental Satellites (GOES) data through other means. The FCC also said it wanted input on which nonfederal agencies get GOES data directly, as opposed to indirectly such as via the Internet. Comments in RM-11681 are due June 21, replies July 21.