Radar-Communications Convergence: Coexistence, Cooperation, and Co-Design

In this paper, we introduce a radar information metric, the estimation rate, that allows the radar user to be considered in a multiple-access channel enabling performance bounds for joint radar-communications coexistence to be derived. Traditionally, the two systems were isolated in one or multiple dimensions. We categorize new attempts at spectrum-space-time convergence as either coexistence, cooperation, or co-design. The meaning and interpretation of the estimation rate and what it means to alter it are discussed. Additionally, we introduce and elaborate on the concept of 'not all bits are equal,' which states that communications rate bits and estimation rate bits do not have equal value. Finally, results for joint radar-communications information bounds and their accompanying weighted spectral efficiency measures are presented.