Ligado LTE Plans See Multiple Calls for Conditions, Changes

Ligado backers and critics have multiple suggestions for proposed conditions, including giving the Federal Aviation Administration final say on operational power levels and creating exclusion zones around airports, as the company pursues both license modifications and an NPRM for its planned LTE network. Tuesday was the deadline for reply comments on Ligado's request to modify its L-band mobile satellite service network license. Tuesday was also the deadline for initial comments on a sister proceeding seeking to allocate and auction 1675-1680 MHz for shared use with the National Oceanic and Atmospheric Administration, with replies due July 21.

Numerous parties voiced concerns about possible impacts on aviation GPS and NOAA weather data in docket 12-340 and RM-11681. "This is what we wanted -- we wanted people to come in and air these issues," Ligado counsel Gerry Waldron of Covington & Burling said in an interview Wednesday. He said that the FCC "now has the building blocks it needs" to make a final decision on the license modifications.

Pointing specifically at potential interference from Ligado's planned use of 1627.5-1637.5 MHz, Iridium said if it and Ligado can't reach an agreement, the FCC should require a reduction of out-of-band emissions (OOBE) from Ligado mobile terminals into Iridium adjacent spectrum at 1616-1626.5 MHz and use of exclusion zones around airport facilities to protect aeronautical mobile satellite route service communications. But Iridium said in its filing Wednesday Ligado's comments in a recent blog (see 1606070022) "suggest a resolution is possible."

Inmarsat was more bullish on the prospects of cooperative agreements. Referencing work it has done since 2012 on rolling out new terminals resilient to the terrestrial component of Ligado's LTE network and the "numerous and substantial modifications" Ligado has made to accommodate it and the GPS industry, Inmarsat said it's "confident that any remaining issues can be addressed through industry cooperation." CTIA and aviation services company Metro Aviation also backed the Ligado proposal. "Given the long timeframes associated with freeing spectrum for mobile services, action is required now to ensure the pipeline does not become depleted," CTIA said, saying repurposing 1675-1680 MHz "is one way to help keep the spectrum pipeline flowing."

Public Knowledge and the Open Technology Institute at New America said in a joint filing that the FCC should create rules for the 1675-1680 MHz band that allow opportunistic and unlicensed access to unused portions of the band on a use-or-share basis. The public interest groups pushed for similar conditions on Globalstar's proposal for a terrestrial low-power service (see 1603250042).

Multiple parties questioned whether weather data distribution can survive the Ligado plan. Lockheed Martin said that since NOAA meteorological satellites operate in adjacent L-band, NOAA first should study the feasibility of alternative means for real-time distribution of weather information before the FCC moves on 1675-1680 MHz band reallocation. A variety of Canadian governmental departments that all use NOAA geostationary operational environmental satellites imagery said they also worried about interference to GOES stations using 1686 MHz from mobile systems operating in the 1670-1680 MHz band. The United Nations' World Meteorological Organization said the U.S. allowing that spectrum be used for non-meteorological purposes "would weaken the ability of other, less influential nations to retain these frequencies for meteorological observing and hydrological management." It said cloud distribution of GOES information isn't reliable enough to ensure forecasting and warning capabilities information that originates in part in the 1675-1680 MHz spectrum.

Ligado's talks with parties to calm fears about interference are useful, but too many interference issues remain unresolved, a group of aviation industry parties said. Chief among those concerns involves certified aviation receivers and Ligado's pledge to protect them from interference, since any condition crafted by the FAA -- as the expert agency -- runs into the problem of the FCC being able to ensure effective regulatory oversight, the group said. They also said the FCC shouldn't act on the application until after further study of those interference issues and development of solutions. Filing were the Aircraft Owners and Pilots Association, Airlines for America, Aviation Spectrum Resources, Bristow Group, Helicopter Association International, International Air Transport Association, National Air Transportation Association, National Business Aviation Association, Southwest Airlines and United Parcel Service.

Any FCC approval needs to ensure the FAA sets Ligado's operational power levels, the Aerospace Industries Association said. It said any FCC decision should wait until the FAA has weighed in how Ligado's planned uplink bands in 1626-1660.5 MHz might affect aviation. Garmin also said the FCC and FAA will need to look at some route to cross-agency enforcement.

Consumer GPS devices will be protected by the concessions in its modification applications such as relinquishing use of 1545-1555 MHz for terrestrial service satellite show industry concerns "can be -- and are being -- effectively resolved through ongoing cooperation," Ligado commented. It said the basis for Iridium concerns is murky since Ligado's OOBE reductions below levels set in FCC regulations "would make the radiofrequency environment even more benign than the one Iridium should have anticipated." Ligado also brushed off worries about effects on industrial high-precision GPS devices, saying they lack specific relevant technical information and likely can be resolved through the type of coordination that resolved other GPS industry concerns.

Specifically focusing on Ligado's request for auction of a reallocated 1675-1680 MHz band, Dish Network said that band first should be licensed on an economic area basis akin to what the FCC did with AWS-3 and H block spectrum. It also said the agency should reject the idea of Ligado getting bidding credits since "it never actually held the terrestrial rights it purports to be giving up."

Numerous commenters criticized Ligado's rejection of a 1 dB rise in carrier-to-noise ratio as the standard for measuring interference tolerance -- an issue that become contentious in the proceeding (see 1605240021).