AT&T Labs wants experimental license to test fixed non-line-of-sight at 3.5 GHz

AT&T Laboratories is asking the FCC to grant an experimental license so that its engineers can conduct tests on multiple new 5G radio systems with integrated adaptive antennas in the 3.5 GHz range. The tests are to take place in Cumming, Georgia, just outside Atlanta.

The application filed with the FCC did not name specific equipment manufacturers, but said multiple companies will be supplying 12 test units. The experiment is intended to last 12 months.

“We hope to evaluate various performance characteristics of the system in a real world Rural/Suburban outdoor environment,” the application stated. “Performance characteristics such as data throughput, latency, error rates, availability and susceptibility to and generation of self and external interference will be investigated.”

The radios they’re evaluating will be installed and tested by AT&T Laboratories personnel using microwave radio and digital communications test equipment. Each radio unit weighs about 12 pounds and is housed in a weatherproof outdoor enclosure. Each radio unit consists of a transmitter, a receiver and an integrated adaptive beamforming antenna. The maximum transmitter power of radio unit will not exceed 47 dBm / 10 MHz EIRP in rural areas and 30dBm / 10MHz EIRP in Urban areas.

“Much of the experimentation will be centered around the evaluation of the integrated adaptive antenna system in a non-line-of-sight (NLOS) environment, so the exact antenna gains and beam widths to be realized are unknown at this time,” the company stated. “However, the maximum gain of any antenna deployed will not exceed 20 dBi. Furthermore the main lobe of any antenna deployed will be pointed approximately to the horizon plus or minus 10 degrees. The azimuthal orientation of the main lobe of the antenna may be arbitrary.”

Specifically, the radio transmitters may use spectrum from 3550 MHz to 3700. Depending on how it’s configured, each radio will use a digitally modulated 10 MHz, 20 MHz or 40 MHz channel in the 3.5 GHz band.

The FCC earlier this year finalized rules for the 3.5 GHz band, 3550-3700 MHz, which it called the Citizens Broadband Radio Service (CBRS) band, setting the stage for Spectrum Access System (SAS) administrators and Environmental Sensing Capability (ESC) operators. The commission was able to open up 100 megahertz of spectrum previously unavailable for commercial uses, which it added to existing commercial spectrum to make a 150 megahertz contiguous band.  

Last week, six companies announced the launch of the CBRS Alliance to help foster the development of LTE-based solutions using the 3.5 GHz band. Qualcomm, Nokia, Intel, Google’s Access Technologies, Federated Wireless and Ruckus Wireless unveiled the CBRS Alliance, building on an earlier agreement to help develop an ecosystem centered on the CBRS airwaves. More entities are expected to formally join the effort, including device makers and operators.

For more:
- see the application 

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