AT&T Releases More Details on its In-flight 4G LTE Wireless Proposal

In May I reported on AT&T's plans to offer 4G LTE in-flight Internet connectivity. Earlier this month AT&T and its affiliated companies filed a Petition for Rulemaking with the FCC that describes the spectrum the service would use and maximum power levels for terrestrial and airborne transmitters.

In its Petition, AT&T asks the FCC to modify Section 27 of the commission rules to add the definition for an “Avionics station,” which the company described as “a station installed on an aircraft that is part of a service using the 2305-2320 MHz and 2345-2360 MHz. A station may consist of multiple physical transceivers operating as a single system.” This spectrum includes the WCS A, B, C and D blocks. The C and D blocks are adjacent to Sirius and XM Radio Satellite Digital Audio Radio Service spectrum.

AT&T has moved forward with plans to use WCS A and B Blocks—which are not immediately adjacent to the SDARS spectrum—in its mobile LTE network. However, in the filing it said “AT&T has continued to struggle to develop uses for its WCS C and D Block spectrum given the strict transmission limits to protect adjacent band operations from harmful interference.”

The filing continues, “AT&T has now found a way to put the C and D Block spectrum to productive use without infringing upon its spectral neighbors. AT&T plans to launch a high-speed 4G LTE-based in-flight connectivity service for airlines and passengers in commercial, business, and general aviation.”

Ground to air base stations will transmit on the D Block spectrum (2345-2350 MHz) while the air-to-ground “Avionics Stations” will transmit on C Block spectrum (2315-2320 MHz). AT&T said it expects to begin offering this service as soon as late next year and will provide coverage of the 48 contiguous states at a variety of altitudes, including robust, uninterrupted service to all routes within the contiguous United States among 50 or more airports classified as large or medium hubs by the FAA.

AT&T notes that in January 2012 Sirius XM Radio, Inc., in an Ex Parte notice, “encouraged efforts to explore other uses of the WCS spectrum—such as the ground-to-air service recently proposed by GoGo, Inc.—that may be more compatible with adjacent band users.” AT&T's proposed rules would provide numerous protections to SDARS, including testing for interference before a commercial launch.

Base stations operating in the 2345-2350 MHz band transmitting to avionics stations would be allowed to exceed 2,000 watts peak EIRP, with the provision that “the average EIRP of such base station shall not exceed 2,000 watts.” Mobile and portable stations would not be permitted to transmit in the 2315-2320 MHz and 2345-2350 MHz bands, except that avionics stations may transmit in the 2315-2320 MHz band and there may be only one avionics station on each aircraft.

Avionics stations would be allowed to operate at up to 8 watts average EIRP per transmitter with the total average EIRP per avionics station not to exceed 16 watts at 20,000 feet above ground level (AGL), 8 watts at or above 10,000 feet and below 20,000 feet AGL, 1 watt at or above 1,000 feet AGL and below 10,000 feet AGL, and 0.25 watt below 1,000 feet AGL and on the ground.

Last week the FCC issued a Notice request comment on AT&T's petition. Comments are due Sept. 22, 2014. The deadline for reply comments is Oct. 6, 2014.

For more details on AT&T's proposed airborne WCS operations, refer to its Petition for Rulemaking.

Two weeks ago, Mike Dano outlined AT&T's plans in his article AT&T: We're using WCS C, D Block spectrum for in-flight Wi-Fi because of interference concerns. In that article, Dano writes, “AT&T's plans put it into direct competition with existing in-flight connectivity providers like Gogo, Row 44, Inmarsat and others. Interestingly, those companies aren't standing still either. Gogo recently requested a 'special temporary authorization' from the FCC to perform testing 'in the 3650-3700 MHz band as well as the various 5 GHz ISM bands (including 5.725 to 5.825 GHz).'”

See my article AT&T Announces 4G LTE In-Flight Internet Connectivity – Plans call for rollout by end of 2015 for a discussion of the original announcement. Qualcomm has also proposed using the 14.0-14.5 GHz Ku-band uplink spectrum for ground-to-air-to-ground links.

It is clear companies feel there is a business in providing Internet access to planes in flight. I've seen stories recently that airlines are giving up seat back displays for services they provide over in-flight Wi-Fi, allowing them to reduce weight, power consumption and maintenance costs while still making money off of in-flight entertainment.

Doug Lung

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.