New Reports Explore LTE-Radar Interference in 3.5 GHz Band

July 2014

To support the Administration's commitment to making available an additional 500 MHz of spectrum for commercial use by 2020, ITS continues to perform and publish technical studies in bands proposed for sharing. In collaboration with a wireless technology provider, earlier this year engineers from ITS and NTIA's Office of Spectrum Management (OSM) jointly performed ground-breaking interference-effects testing between radar signals and broadband digital communication receivers in the 3550-3650 MHz (3.5 GHz) band. In July, ITS released two reports that describe these measurements and analyses.

NTIA Technical Report TR-14-506, co-authored by Geoffrey A. Sanders, John E. Carroll, and Frank H. Sanders of ITS with Robert L. Sole of OSM, presents the results of measurements and analyses of the effects of radar interference on prototype LTE equipment that might in future operate in that band. NTIA Technical Report TR-14-507, co-authored by Frank H. Sanders, John E. Carroll, Geoffrey A. Sanders, and Robert J. Achatz of ITS; Robert L. Sole of OSM; and Lawrence S. Cohen of the U.S. Naval Research Laboratory, presents the results of measurements and analyses of the effects of LTE interference on a type of radar receiver that might eventually share spectrum with such systems.

Using these data, spectrum managers can refine and update the electromagnetic compatibility (EMC) analyses originally presented in NTIA's "Fast Track Report" for possible future spectrum sharing between LTE and radars in the 3.5 GHz band. The reports do not identify interference protection criteria (IPC) for either the tested radar type or the tested LTE networks. But the measurement results may be used to guide the development of band-sharing EMC criteria. These data will be critically important to government and private-sector engineers and spectrum regulators as spectrum sharing opportunities in the band are explored. They will need to determine the conditions under which future LTE-type broadband systems may be able to share 3.5 GHz spectrum with high-power, incumbent government radar systems.

NTIA welcomes technical readers to review these data and share questions or comments with the authors.