Photonics-assisted Millimeter-Wave Multiband Integrated Sensing and Communication System Using Coherent Receiving

Multiband integrated sensing and communication (ISAC) systems towards multiple functions and multiple users will play an important pole in future 6G wireless networks. Here, we propose and experimentally demonstrate a multiband ISAC system using optical frequency upconversion and coherent receiving techniques for millimeter-wave (MMW) high-capacity wireless communication and high-resolution sensing functions. The MMW multiband ISAC signals are simultaneously generated by a single photonic MMW frequency upconverter consisting of an optical frequency comb, a wavelength selective switch, an I/Q Mach-Zehnder modulator, and a high-speed photodetector. A multi-channel coherent photonic MMW de-chirper with phase compensation is utilized for coherent multiband radar signal processing, which facilitates the coherence-processing-free multiband data fusion and thus leading to an ultra-high resolution radar detection. Meanwhile, the communication receiving and demodulation towards multiband/multiuser scenarios are achieved by coherent receiving technology. In experiments, a photonic MMW ISAC system delivering Ka-band and V-band wireless signals is implemented, achieving a communication data rate of 16 Gbit/s and a two-dimension radar imaging of 3.75-cm range resolution, respectively. More importantly, after the multiband data fusion, an 8.6-mm ultra-high resolution is successfully achieved for radar ranging and imaging.