Joint Sensing and UE Positioning in 5G-6G: PRS Range Estimation with Suppressed Ambiguity

This paper focuses on cellular integrated sensing and communications (ISAC), with particular focus on downlink where the positioning reference signal (PRS) is the primary physical resource for high-accuracy delay estimation and ranging. The PRS allows for large bandwidths, and thus high ranging accuracy, however, the involved comb-like subcarrier patterns induce ambiguity challenges in both positioning and sensing. In this paper, alternative time-/frequency-domain solutions to resolve or relax the ambiguity challenges are described, discussed and proposed. Specifically, new irregular resource patterns are introduced, allowing for high-accurate downlink sensing with suppressed ambiguity while at the same time supporting also ordinary UE positioning services. Corresponding numerical results are also provided, evidencing and highlighting the benefits of the proposed approach.