Spectral Cohabitation and Interference Mitigation via Physical Radar Emissions

Auctioning of frequency bands to support growing demand for high bandwidth 5G communications is driving research into spectral cohabitation strategies for next generation radar systems. The loss of radio frequency (RF) spectrum once designated for radar operation is forcing radar systems to either learn how to coexist in these frequency spectrum bands, without causing mutual interference, or move to other bands of the spectrum, the latter being the more undesirable choice. Two methods of spectral cohabitation are presented in this work, each taking advantage of recent developments in non-repeating, random FM (RFM) waveforms. RFM waveforms are designed via one of many different optimization procedures to have favorable radar waveform properties while also readily incorporating agile spectrum notches. The first method of spectral cohabitation uses these spectral notches to avoid narrow-band RF interference (RFI) in the form of other spectrum users residing in the same band as the radar system, allowing both to operate while minimizing mutual interference. The second method of spectral cohabitation uses spectral notches, along with an optimization procedure, to embed a communications signal into a dual-function radar/communications (DFRC) emission, allowing one waveform to serve both functions simultaneously. Results of simulation and open-air experimentation with physically realized, spectrally notched and DFRC emissions are shown which demonstrate the efficacy of these two methods of spectral cohabitation.