Superposition of PRS and PDSCH for ISAC System: Spectral Efficiency Enhancement and Range Ambiguity Elimination

TL;DR

This paper proposes a superposition scheme of PRS and PDSCH signals in 5G NR to enhance spectral efficiency and eliminate range ambiguity in ISAC systems, supported by simulation results showing significant performance improvements.

Contribution

It introduces a novel superposition method and interference reduction algorithm for PRS and PDSCH, enabling integrated sensing and communication with improved accuracy and efficiency.

Findings

Range ambiguity is eliminated using joint PRS and DMRS exploitation.

Spectral efficiency is improved by superposing PRS and PDSCH signals.

Simulation shows up to 57% BER improvement and throughput enhancement.

Abstract

From the telecommunication companies' perspective, the preference for integrated sensing and communication (ISAC) for sixth-generation (6G) is to enhance existing infrastructure with sensing capabilities while minimizing network alterations and optimizing available resources. This prompts the investigation of ISAC leveraging the existing infrastructure of fifth-generation (5G) new radio (NR) signals as defined by the 3rd generation partnership project (3GPP). Additionally, improving spectral efficiency is crucial in scenarios with high demand for both communication and sensing applications to maintain the required quality of service (QoS). To address these challenges, we propose the superposition of the physical downlink shared channel (PDSCH) for communication and the positioning reference signal (PRS) for sensing with proper power allocation. Furthermore, we propose a novel algorithm to reduce the interference for data decoding caused by PRS. Moreover, we introduce the joint exploitation of PRS and demodulation reference signal (DMRS) to prevent range ambiguity in the form of ghost targets. Through simulation analysis, we demonstrate the effectiveness of integrating PDSCH and PRS symbols within a unified resource grid. Our results show that the introduced approaches not only eliminate range ambiguity when sensing targets from gNBs but also enhance spectral efficiency by reducing interference between PRS and PDSCH. Simulation results show throughput enhancement and up to 57% improvement in bit error rate (BER). This paves the way for supporting sensing applications in the forthcoming network generation.