3.5 GHz environmental sensing capability sensitivity requirements and deployment

Abstract

Spectrum sharing in the 3.5 GHz band between commercial and government users along U.S. coastal areas depends on an Environmental Sensing Capability (ESC), a network of radio frequency sensors and a decision system, to detect the presence of incumbent shipborne radar systems and trigger protective measures, as needed. It is well known that the sensitivity of these sensors depends on the aggregate interference generated by commercial systems to the incumbent radar receivers, but to date no comprehensive study has been made of the aggregate interference in realistic scenarios and its impact on the requirement for detection of the radar signal. This paper presents systematic methods for determining the required sensitivity and placement of ESC sensors to adequately protect incumbent shipborne radar systems from harmful interference. Using terrain-based propagation models and a population-based deployment model, the analysis finds the offshore distances at which protection must be triggered and relates these to a minimum required signal detection level at coastline sensors. We further show that sensor placement is a form of the well-known set cover problem, which has been shown to be NP-complete, and demonstrate practical solutions achieved with a greedy algorithm. Results show required sensitivities to be 4 dB to 16 dB lower than required by current industry standards. The methodology and results presented in this paper can be used by ESC operators for planning and deployment of sensors and by regulators for testing sensor performance.