EMC Measurements for Spectrum Sharing Between LTE Signals and Radar Receivers

Abstract: In response to proposals to introduce new Long Term Evolution (LTE) microcell Citizens Broadband Service (CBS) radio systems into 3550–3650 MHz (3.5 GHz) radio spectrum in the United States, the authors have performed measurements and analysis on effects of LTE interference on the performance of a type of radar receiver that might eventually share spectrum with such systems. LTE and Gaussian noise interference were injected into a radar receiver; Gaussian noise was a proxy for aggregated interference sources and one type of LTE. Interference was injected into a radar receiver so as to appear coincident with synthetic radar targets on the radar’s display. The targets’ baseline (non-interference) probability of detection (Pd) was 90 percent. With interference present, the targets’ Pd was measured and recorded as a function of LTE signal (both on-tuned and off-tuned) and Gaussian noise interference levels. Additional data presented in this report include: the radar receiver’s antenna radiation pattern, RF front end frequency response, IF-stage frequency response, noise figure, and RF overload response up to an input power of -4.6 dBm. A measured LTE emission spectrum is also provided. Using these data, spectrum management personnel can perform electromagnetic compatibility (EMC) analyses for possible future spectrum sharing between LTE transmitters and this type of radar receiver.

Keywords: 3.5 GHz spectrum sharing; Citizens Broadband Service (CBS); interference effects; interference protection criteria (IPC); Long Term Evolution (LTE); microcells; radar; small cells; spectrum access system (SAS); spectrum sharing

The full report is available at http://www.its.bldrdoc.gov/publications/2760.aspx