Integrated Sensing and Communication System via Dual-Domain Waveform Superposition

TL;DR

This paper introduces a dual-domain waveform for integrated sensing and communication in 6G networks, superposing OFDM and delay-Doppler sensing signals, achieving enhanced sensing resolution with minimal impact on communication performance.

Contribution

It proposes a novel dual-domain waveform design that combines FT and delay-Doppler domains, enabling improved sensing and communication performance with significant power savings.

Findings

Outperforms OFDM and OTFS in delay estimation accuracy (up to 20 dB CRB improvement).

Achieves sensing performance with at least 30 dB power reduction compared to communication signals.

Maintains communication performance with negligible rate penalty.

Abstract

Integrated Sensing and Communication (ISAC) systems are recognised as one of the key ingredients of the sixth generation (6G) network. A challenging topic in ISAC is the design of a single waveform combining both communication and sensing functionalities on the same time-frequency-space resources, allowing to tune the performance of both with partial or full hardware sharing. This paper proposes a dual-domain waveform design approach that superposes onto the frequency-time (FT) domain both the legacy orthogonal frequency division multiplexing (OFDM) signal and a sensing one, purposely designed in the delay-Doppler domain. With a proper power downscaling of the sensing signal w.r.t. OFDM, it is possible to exceed regulatory bandwidth limitations proper of legacy multicarrier systems to increase the sensing performance while leaving communication substantially unaffected. Numerical and experimental results prove the effectiveness of the dual-domain waveform, notwithstanding a power abatement of at least 30 dB of the signal used for sensing compared to the one used for communication. The dual-domain ISAC waveform outperforms both OFDM and orthogonal time-frequency-space (OTFS) in terms of Cram\'{e}r-Rao bound on delay estimation (up to 20 dB), thanks to its superior resolution, with a negligible penalty on the achievable rate.