Report finds no interference in lower 700 MHz channels in response to FCC NPRM


A handful of lower 700 MHz spectrum holders released a report showing that concerns regarding interference across the spectrum bands A-Block are unfounded and that current proceedings designed to preclude that spectrum block from 3GPP standards for LTE will limit roaming capabilities.

The report, which was commissioned by Cavalier Wireless, C Spire Wireless, Continuum 700, King Street Wireless, MetroPCS Communication, U.S. Cellular and Vulcan Wireless, was in response to open comments sought by the Federal Communications Commission’s pending 700 MHz Interoperability Notice of Proposed Rule Making.

In the report, the lower 700 MHz spectrum holders noted that field testing in the Atlanta area showed there was no interference between television transmissions operating in channel 51 adjacent to the A-Block uplink channel nor from the unpaired E-Block slice of 700 MHz spectrum operating adjacent to the A-Block downlink channel. Following the results, the companies said the FCC should move to do away with the current Band Class 17 proposal that would only include the lower B- and C-Block spectrum for 3GPP approval and move forward with the Band Class 12 proposal that would include the lower A-Block channels.

The move is seen as important to lower A-Block spectrum holders as the inclusion of the channel in the standard would mean that devices and equipment would work across all three bands and thus provide for interoperability between equipment.

AT&T Mobility is currently pressing for the FCC to move forward with the Band Class 17 proposal as it has expressed concern that interference in the A-Block will hinder the deployment of its LTE services that use its B-Block spectrum holdings.

“Laboratory tests of AT&T commercial devices used test procedures, which effectively removed the narrower Band Class 17 duplexer from consideration, quantifying the performance of the receiver itself,” the report noted. “The test results are equally applicable to a Band Class 12 device employing the same receiver but using the wider Band Class 12 duplexer. The laboratory and field tests validate that no interference would result to Lower B- and C-Block operations if Band Class 12 devices were employed near Lower E-Block and Channel 51 broadcast stations.”

Interoperability across the 700 MHz band has been a significant issue for a number of regional carriers that picked up spectrum during the FCC auction in 2008. Those carriers, along with the Rural Cellular Association, have been asking the FCC to require interoperability across the 700 MHz commercial bands, though so far that has not been accomplished.

Verizon Wireless, which is currently relying on its upper C-Block license in the 700 MHz band for its LTE rollout, has told its device makers that they do not need to include support for other bands in its equipment specifications. This move raised concern among rural operators that are dependent on larger carriers to provide roaming services to their customers.

Verizon Wireless has attempted to soothe those concerns with its LTE in Rural America program that allows rural operators to use the carrier’s upper C-Block licenses to rollout LTE services and includes a reciprocal roaming agreement. More than a dozen carriers have signed onto the program, with commercial launches expected by mid-year.

Verizon Wireless has also recently raised concerns by offering to auction off its current A- and B-Block 700 MHz licenses if it gains approval for its attempt to acquire 1.7/2.1 GHz spectrum holdings from a number of cable operators. The carrier said the move to auction off the spectrum would show the carrier is not “warehousing” spectrum in an attempt to keep it from competitors. The move would also reinforce the carrier’s 1.7/2.1 GHz spectrum holdings that it plans to use to add capacity to its LTE network that would be a greater challenge due to potential interference issues from using more 700 MHZ spectrum.

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Dan Meyer

Editor-in-Chief, Telecom Software, Policy, Wireless Carriers
Dan Meyer started at RCR Wireless News in 1999 covering wireless carriers and wireless technologies. As editor-in-chief, Dan oversees editorial direction, reports on news from the wireless industry, including telecom software, policy and wireless carriers, and provides opinion stories on topics of concern to the market such as his popular Friday column “Worst of the Week.”