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AT&T waves in 70-80 GHz band for wireless broadband trials

AT&T has revealed it will be using the 70 GHz to 80 GHz spectrum band in its trials for point to point millimeter wave (mmWave) wireless and wireline technologies, to bring speeds of 100 Mbps to residences outside of its current 21-state fixed line footprint.

The US operator announced its trials in Minneapolis last week, but kept the spectrum details to itself, until an AT&T spokesperson told FierceWirelessTech this week that the operator has its hands on a nationwide license for services in the 70 GHz to 80 GHz band.

The industry has been exploring solutions for a synergistic working between powerline and wireless to bring affordable broadband to homes, by harnessing existing infrastructure. AT&T’s current trials are using small antenna systems on rooftops to distribute ultra-fast internet speeds from a fiber-connected property to neighboring properties – enabled by mmWave technologies which offer high-capacity wireless signals. These signals are then converted into wired internet connections using either existing wiring or by installing new wiring.

The 70 GHz to 90 GHz band has been allocated as ‘lightly licensed’ for multi-gigabit wireless communications, in the extremely high frequency (EHF) band, which offers speeds that cannot be achieved at the lower, bandwidth-limited bands, but using this chunk of spectrum for wireless broadband doesn’t come without its difficulties. It requires unobstructed line of sight communications, and the short wavelengths in this type of spectrum are susceptible to conditions such as rain and fog, as well as obstacles such as trees and the reflections caused by water and leaves.

However, new antenna arrays are being developed to avoid this problem, so that millimeter waves do not have to be lined up like microwave point to point communication – to avoid certain obstacles.

High bands such as 80 GHz are expected to host 5G networks from the 2020s, but AT&T has stressed that this trial is not a 5G radio protocol, as with the 28 GHz and 39 GHz bands and above which are involved in ongoing 5G trials in the US. AT&T also remains tight-lipped about the vendors involved in its 70 GHz to 80 GHz trials.

Residents in apartment buildings in Minneapolis participating in these trials will also be able to receive AT&T’s DirecTV service, by sending a video signal to a single satellite dish on the building which goes to a centralized distribution system in the apartment building – without each apartment requiring its own satellite dish.

Currently the FCC does not allow mobile operations in the mmWave bands where Verizon’s tests are heavily focused, although it proposes to change that – which would certainly throw a spanner in the works as the FCC would likely welcome applications from companies seeking to be Spectrum Access System (SAS) administrators.

However, critics such as T-Mobile have complained that the FCC has been too narrow, rejecting the 42 GHz, 32 GHz, 70 GHz and 80 GHz bands even though they each have at least 500 MHz of contiguous spectrum available.

We’re trialing the latest innovations in wireless and wired network technologies. This will make it possible for us to potentially deliver an internet connection to more locations where we have not previously been able to offer a home internet connection,” said Ed Balcerzak, SVP of Commercial and Connected Communities at AT&T. “If successful, this will give us the ability to offer a combination of internet, DirecTV and wireless services to apartment complexes and multifamily communities in additional metro areas.”

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