AT&T (NYSE:T) worked with Qualcomm (NASDAQ:QCOM) and its network vendor partners to implement a 700 MHz interoperability solution that will allow the carrier to support Band Class 12 devices, according to a senior AT&T executive.
John Donovan, AT&T's senior executive vice president of technology and network operations, said the solution came about through work between AT&T engineers and counterparts at Qualcomm as well as Ericsson (NASDAQ:ERIC) and Alcatel-Lucent (NYSE:ALU), the carriers' two main LTE network vendors. "The breakthrough for us, technologically, was a feature that allows a single slot at 700 [MHz] to communicate from handset to the network and dedicate [the handset as] either as Band 12 or Band 17," he said Wednesday at the Bank of America Merrill Lynch Media, Communications & Entertainment Conference.
Lower A Block licensees have argued that vendors like Apple (NASDAQ:AAPL) make equipment for AT&T's Band Class 17 and Verizon Wireless' NYSE:VZ) spectrum in Band Class 13, but not for those smaller companies such as C Spire Wireless and U.S. Cellular (NYSE:USM) that hold 700 MHz A Block spectrum in Band Class 12. AT&T previously argued it could not support Band Class 17 alongside Band Class 12 because it would be too expensive and would cause interference.
"We didn't change our minds," Donovan asserted. "We solved the problem." He said AT&T had "broke through with an innovation" that ultimately was "not a political compromise but it made political compromise possible" in the dispute.
Donovan said that AT&T had for years been faced with a dilemma. It could choose to build devices that would interoperate with Band Class 12, but such a move would make it impossible for the carrier to support its other bands due to technical limits on the number of bands that could be squeezed into devices' radios. The new technical solution that lets devices switch between Band Class 12 and Band Class 17 solves the issue, he said.
In a filing with the FCC, AT&T provided some additional details about the modification to its network that will allow it to support Band Class 12. Specifically, the company said it must develop, implement and deploy throughout its network a multi-frequency band indicator, or MFBI, capabilities that will let its network operate simultaneously in both Band 12 and Band 17 and support devices in both bands. That is the solution Donovan was referring to. The feature was recently standardized but will require lab testing and field testing, the carrier said. The field testing will have to use existing Band 17 legacy devices with carrier aggregation capabilities operating with the MFBI feature.
Also at the conference, Donovan touched on other technical issues. He said that when AT&T launches LTE Advanced features, specifically carrier aggregation, that will remove some complexity from AT&T's network, since it will be able to meld together disparate spectrum bands. He did not give timeframe for when AT&T would launch carrier aggregation. With that feature in hand, the wireless world "moves from a game of exactly where your spectrum is to a game where total spectrum is going to be a determinant of what your network capacity is."
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