News Feature | September 6, 2016

AT&T Testing 5G Service On 3.5 GHz Spectrum

By Jof Enriquez
Follow me on Twitter @jofenriq

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AT&T Laboratories has applied with the Federal Communications Commission (FCC) for an experimental license to test 5G radios with integrated adaptive, non-line-of-sight (NLOS) antennas transmitting in the 3.5 GHz range.

Each 12-pound radio unit consists of a transmitter, a receiver, and an integrated adaptive beamforming antenna, and will be housed in a weatherproof outdoor enclosure, according to the FCC filing by AT&T. No more than ten radio transmitters (two types of radio mounts, shown in Figs. 1 & 2) will be installed at outdoor locations in Cumming, Ga. and Atlanta, Ga. Technical specifications for the radio stations in each location are provided in FCC Form 442.

"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,” states the application. "The radio transmitters may occupy spectrum from 3550 MHz to 3700. Depending on how it is configured, each radio will use a digitally modulated 10 MHz, 20 MHz or 40 MHz channel in this band."

During a proposed experiment duration of 12 months, AT&T says it will evaluate performance characteristics such as data throughput, latency, error rates, availability, and susceptibility to and generation of self and external interference.

This new testing by AT&T is one of several fixed wireless and fifth-generation (5G) solutions being tested by the company and recently acquired DirecTV, according to DSL Reports.

It follows last month's filing by Google to test its own wireless network of experimental transmitters operating on frequencies between 3.4 GHz and 3.8 GHz in 24 locations in the United States.

AT&T's application also comes one week after formal formation of the Citizens Broadband Radio Service (CBRS) Alliance formed by six major wireless companies, namely Alphabet’s Access Technologies, Federated Wireless, Intel, Nokia, Qualcomm, and Brocade’s Ruckus Wireless, notes Wireless Week. The group plans to conduct LTE (long-term evolution) CBRS field trials in the second half of this year.

CBRS was formally launched by FCC on April 17, 2015 for shared wireless broadband use of the 3550-3700 MHz frequency band (3.5 GHz Band) primarily used by the U.S. Department of Defense (DOD) for the operation of radar systems. The three-tiered, dynamic spectrum access system seeks to accommodate a variety of commercial uses on a shared basis with incumbent federal and non-federal users of the band. CBRS has safeguards in place to protect incumbent radar systems from interference, while allocating additional spectrum for wireless broadband for consumer and industrial applications.