NextLink Wireless submitted a revised Reed Engineering study to the FCC that supports a recent analysis filed by T-Mobile USA in which T-Mobile found that next-generation wireless broadband operations in the 31.8-33.4 GHz band could coexist with adjacent operations in a neighboring band.
NextLink noted that some revisions were done to the studies it previously submitted to the FCC but said the overall conclusion remains the same: 5G deployments in the 31.0-31.3 GHz band can protect the Earth exploration satellite service (EESS), as well as the radio astronomy service (RAS) and space research service, from harmful interference.
“The Reed Engineering and T-Mobile studies provide concrete evidence that next-generation mobile wireless services can coexist with passive band services in the 31.3-31.8 GHz band,” NextLink said in its filing submitted Oct. 17 by attorney Michele Farquhar.
Earlier this month, T-Mobile submitted a technical study regarding how best to promote 5G deployment in the bands above 24 GHz, zeroing in on the 32 GHz, 47 GHz and 50 GHz bands, which it said can coexist with existing RAS and EESS.
T-Mobile’s study notes that the FCC proposed allocating the 31.8-33.4 GHz band for next-gen wireless broadband. Immediately below that band, however, is a 500 megahertz-wide primary allocation for RAS, EESS and other passive services such as space research. Of the three millimeter-wave bands under consideration for supporting 5G, the 32 GHz band has relatively favorable propagation characteristics compared to the 47 GHz and 50 GHz bands.
But even the 32 GHz band can coexist with passive services in adjacent band spectrum for numerous reasons, including the necessity of using beamforming to overcome the propagation limitations associated with millimeter-wave spectrum, the study said. Beamforming and other 5G innovations are offered up as methods of permitting 32 GHz broadband deployments to coexist with passive services.
T-Mobile said that in each of the bands studied, the RAS, EESS and other passive services can be protected by adopting “modest operating constraints” on new 5G broadband services. “For example, adopting geographic separation and coordination zone requirements can protect RAS operations with little effect on 5G deployments nationwide because RAS sites are limited in number and mostly located in remote areas,” the operator said.
Similarly, technical innovations in 5G systems will substantially limit the aggregate amount of out-of-band emissions EESS will experience even under line-of-sight conditions. T-Mobile also said its study of 5G coexistence scenarios offers an important foundation for further analysis, but that any real-world conditions are likely to prove much more favorable to coexistence than the assumptions it employed for the study.