FCC Opens Rulemaking to Explore 700 MHz Band Interference, Interoperability

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By Paul Barbagallo  

The Federal Communications Commission voted unanimously March 21 to solicit public comment on whether new rules are needed to ensure that mobile devices used in the lower 700 MHz band of spectrum can operate on airwaves used by different carriers, including Verizon Wireless and AT&T Inc.

Several regional carriers have alleged that Verizon and AT&T are pressuring manufacturers of handsets, chipsets, and network equipment to make their products compatible only with Verizon- and AT&T-occupied spectrum in the band.

The carriers, led by the Rural Cellular Association, have argued that absent FCC action, their customers will be deprived of the latest smartphones and the ability to roam on Verizon and AT&T networks.

In issuing the notice of proposed rulemaking March 21, the FCC asked a series of questions about potential interference in the lower 700 MHz block of spectrum, but stopped short of recommending a strict interoperability mandate.

“An industry-led solution would be the preferable solution, and multiple stakeholders have indicated that a unified band class can be win-win if interference concerns are addressed,” FCC Chairman Julius Genachowski said in a statement. “Of course, we are launching this proceeding because no solution has been reached yet and we will be closely monitoring progress in addition to developing a record as part of this proceeding.”

Genachowski admitted that a “key issue” in the rulemaking will be interference—whether a “unified band class”would result in harmful interference to lower 700 MHz “B”and “C Block” licensees, and whether, if such interference exists, it “reasonably can be mitigated.”

Auction Held, Band Classes Established.

In the 700 MHz-band auction of 2008, Verizon acquired most of what is known as the C Block, paying $9.6 billion for 108 licenses. AT&T bought 227 licenses for $6.6 billion in the B and C blocks. A number of smaller mobile network operators purchased licenses in the lower A, B, and C blocks.

After the auction, the 3rd Generation Partnership Project (3GPP), an industry standards-setting body, created four band classes within the 700 MHz band—12, 13, 14, and 17. Band class 13 was designated for Verizon's upper C Block spectrum; band class 17 for AT&T's lower B and C block spectrum; and band class 12 for the smaller operators' lower A, B, and C block spectrum. Band class 14 was created for the upper B Block and spectrum allocated for public safety use.

All handsets, chipsets, and network equipment made for band class 13 are incompatible with band class 17 or band class 12, and vice versa. And most manufacturers are making gear only for Verizon and AT&T.

“Interoperability is the goal,” Genachowski said during a post-meeting press conference. “3GPP continues to look at it. The stakeholders continue to look at it. Interoperability is important. We prefer to see a private, industry-led solution. But we all believe that the appropriate thing to was to act to launch this proceeding because an industry-led solution hasn't arrived. We're all hopeful that this will become a vehicle and a spur to achieve interoperability in the band.”

Interference Issues Real, Say Verizon, AT&T.

To Verizon and AT&T, regulatory mandates would undermine the standards processes at the 3GPP.

In rebutting the claims of smaller carriers, both companies have argued that one of the underlying reasons for separating the 700 MHz blocks into different band classes is interference—the proximity of A Block spectrum pairs to TV broadcast transmissions on one hand, and high-power broadcast transmissions in the unpaired 700 MHz D Block and E Block on the other.

“These challenges are well-documented and real,” Joan Marsh, AT&T's vice president of federal regulatory policy, wrote in a March 21 blog post. “The high power broadcasts that are permitted in channel 51 and in the lower E-block create the potential for significant technical and deployment impediments in the neighboring lower 700 MHz blocks. Some have argued that the technical and physical limitations of the band should simply be ignored, and have called for sweeping interoperability mandates [which would] be an unprecedented regulatory intrusion into a carrier's right to manage network and device deployment in a manner best suited to serve its customers.”

Fred Campbell, president and CEO of the Wireless Communications Association International and former FCC Wireless Bureau chief during the 700 MHz auction of 2008, attempted to explain the interference issue in a blog post of his own, noting that the FCC's Office of Engineering and Technology decided to reduce the power limits in the lower band's paired spectrum, which largely resolved the interference issues for the B and C blocks. It did not, however, resolve these issues for the A Block, because it was still adjacent to high-power unpaired spectrum—Channel 51 and the unpaired 700 MHz blocks where Qualcomm was providing a mobile broadcast service, he said.

At that time, the ongoing digital television (DTV) transition, coupled with the Qualcomm deployment, made it “impractical” to resolve these issues before the auction, Campbell said.

“The FCC was subject to Congressional deadlines for completion of the auction and the DTV transition, and there simply wasn't enough time to resolve the A block interference issues while meeting the deadlines,” Campbell wrote, adding: “It's no coincidence that the lower B Block sold for more than double the price of the lower A Block (and much more than the upper C block, which is subject to open platform conditions and interference safeguards related to public safety). The A Block's interference problems made it significantly less valuable than the B block, so the A block sold at a steep discount. As the old saying goes, ‘you get what you pay for.' ”

Still, this does not mean the FCC should ignore the A Block's interference issues, Campbell noted.

“It does mean, however, that the FCC has no rational basis for placing the blame on AT&T,” he added.

Clyburn Wants Interoperability Now.

Though all three commissioners voted for the item, Commissioner Mignon Clyburn chided the actions of the previous commission for failing to anticipate the lack of interoperability when it adopted 700 MHz service rules.

“I understand the interest in giving the industry some time to arrive at a voluntary solution,” Clyburn said. “I agree that, generally speaking, such an approach can offer a market greater flexibility to respond to evolving consumer needs and fast-paced technological developments. But, the industry has already had more than four years to find a solution. This industry knows how to arrive at interoperability. In fact, as I alluded to before, until the splintering of the lower 700 MHz band occurred, the entire mobile wireless industry had been operating with the understanding that this commission expects interoperability within all spectrum bands.”

Several smaller carriers declined to comment on the notice of proposed rulemaking until the text was released.

Rural Cellular Association (RCA) President Steven Berry said in a statement that he was pleased the FCC issued a rulemaking specifically focused on the Lower 700 MHz B and C blocks.

“Many RCA members own spectrum in the Lower 700 MHz spectrum but are unable to build out their networks and compete with others moving to 4G/LTE [fourth generation/long term evolution] because of a lack of interoperability,” Berry said in a statement. “The sooner this is resolved, the faster customers all across the country will have access to 4G/LTE devices and services.”

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