Sensing-Oriented Reference Signal Design for Multi-Target Detection in 6G ISAC Systems

IEEE Communications Letters, vol. 30, pp. 302–306

Abstract

Standard 5G new radio (NR) reference signals (RSs), such as demodulation reference signal (DMRS) and positioning reference signal (PRS), have been proposed for sensing; however, they exhibit structural limitations, such as evenly spaced or sparse patterns, that degrade target detection, introduce ghost targets, and reduce the probability of detecting weak targets in multi-target scenarios. To address these challenges, we propose a sensing-oriented resource element (RE) allocation scheme that optimizes the time-domain spacing of RSs at the orthogonal frequency division multiplexing (OFDM) symbol level, thereby maximizing the detection probability for closely spaced targets while maintaining sparse recovery constraints. The optimized RE pattern is further processed with the complex approximate message passing (CAMP) algorithm, a compressed sensing (CS) method, to generate high-resolution range-Doppler (RD) maps. Simulation results demonstrate that the proposed pattern significantly increases the peak-to-aliasing lobe ratio and increases the probability of detecting weak targets compared to conventional RS patterns in multi-target scenarios.

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