Reiterating a stance popular with U.S. wireless carriers, AT&T is telling the FCC that “5G” and “mmW spectrum” are not, and should not be, synonymous, reminding regulators that to fully realize the potential of 5G, the nation needs access to low-, mid- and high-band capacity.
While AT&T commended the FCC’s efforts with respect to millimeter wave (mmW) spectrum, “it should not lose sight of the need to continue to allocate more spectrum below 6 GHz,” the company said. AT&T made its remarks as part of the FCC’s call for comments regarding its proposals for spectrum bands above 24 GHz.
The FCC’s Further Notice of Proposed Rulemaking (FNPRM) proposed to make additional mmW spectrum bands available for mobile operations and proposed a number of service rules for the added bands. New rules passed in July opened up nearly 11 GHz of high-frequency spectrum for mobile and fixed wireless broadband – 3.85 GHz of licensed spectrum and 7 GHz of unlicensed spectrum.
AT&T said its own initial 5G lab trials have demonstrated 5G’s high speeds and low latency, which are positive signs for future consumer experiences such as self-driving cars and augmented reality, as well as for applications like remote tele-medicine or real-time asset tracking. In June, AT&T announced it was working with Nokia to expand its 5G lab work in mmWave and that it was getting speeds above 10 gigabits per second in early 5G tests with Ericsson.
AT&T also noted that unlike its predecessors, 5G will not consist of a single Radio Access Technology (RAT) but will be supported by a combination of existing RAT and new RATs optimized for specific deployments and use cases. Dense small cell deployments in particular will play a key role in 5G network design.
But AT&T pointed to three technologies in particular that will play a role in 5G network deployments. Those include multiple input, multiple output (MIMO) with adaptive beamforming; flexible low latency radio protocol design; and an access-agnostic software-defined core network.
The operator urged the FCC not to adopt technical rules or performance requirements that may be preclusive of use cases that are not yet fully understood. It also said allocations of large, contiguous channels will be necessary to support 5G’s expected level of performance – 200 MHz at minimum, with even larger blocks where possible. Large channels will be required to attain the kinds of data speeds and meet the capacity requirements expected in 5G.
Not surprisingly, AT&T told the commission it should continue to engage in all necessary technical and engineering efforts to secure exclusively licensed spectrum rather than going down the path of a Spectrum Access System (SAS) sort of model.
“While the SAS concept has been portrayed as a technological enabler, the reality is that the model is still untested, and there are already significant issues coming to the fore as industry struggles with SAS implementation for the 3.5 GHz band,” the operator said. Instead, the commission should look to tested industry/government sharing models, including those adopted in the AWS-3 proceeding, the use of coordination and preclusion zones and the use of prior coordination notice processes.
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