Photonics-Aided THz Integrated Sensing and Communication System Based on a Subcarrier-Chirp Inter-Embedded Waveform

The advancement of integrated sensing and communications (ISAC) technology into millimeter-wave and even terahertz (THz) bands will be crucial for the upcoming sixth-generation wireless access networks. Here, we propose and experimentally demonstrate a photonics-assisted THz ISAC system based on a time-frequency efficient dual-function waveform. The key to designing the ISAC waveform is embedding the subcarrier communication signals in the idle time-frequency dimension of a linear frequency-modulated continuous wave (LFMCW). This subcarrier-chirp inter-embedded (SCIE) method makes full use of the idle time-frequency resources of the LFMCW without compromising its large timebandwidth product, thereby significantly enhancing the time-frequency efficiency of the LFMCW. The experimental findings demonstrate that owing to the novel and simple communication embedding, wireless transmission of an 88-Gbps data rate over a distance of 10.2 m in the 150-GHz band is successfully realized. Simultaneously, multi-user detection with an 8-mm ranging resolution is also realized. By fully utilizing the idle time-frequency resources of the LFMCW, a density of information-resolution quotient of up to 46.2 × 10-2 bit·s/m2 has been achieved. Furthermore, the proposed ISAC system exhibits good frequency tunability and flexible communication modulation formats.