Non-cooperative high-efficiency multi-user ranging using OFDM signals

Joint radar and communication (JRC) is attracting increasing interest due to the finite nature of the electromagnetic spectrum and the importance of spatial positioning in modern communications networks. Focusing on the challenge of utilizing the same spectrum for both communication and sensing among multiple users, we discuss the exceptional properties of waveform orthogonal frequency-division multiplexing (OFDM) for joint communications and sensing. OFDM's excellent correlation properties make it particularly suitable for this purpose. We delve into the theory of performing ranging with OFDM signals, including their cross-correlation with other signals in the same spectral bands, and clarify how multiple users can operate in an environment without being multiplexed in the frequency or time domain. Simulations are presented alongside experimental measurements from a two-user OFDM radar system operating at center frequencies of 1.5 GHz and 1.55 GHz, demonstrating simultaneous operation and the efficient use of spectral resources.