Free Space Optical Integrated Sensing and Communication Based on LFM and CPM
Yunfeng Wen, Fang Yang, Jian Song, Zhu Han
Abstract
Integrated sensing and communication (ISAC) is a crucial component of future wireless networks, with optical ISAC regarded as a promising complement to its radio-frequency counterpart. In this letter, an ISAC scheme combining linear frequency modulation (LFM) and continuous phase modulation (CPM) is proposed for free space optics. The generalized intermediate frequency, the direct-current bias, and the Hilbert transform are adopted to make the complex LFM-CPM signal compatible with optical intensity modulation and direct detection. Additionally, various performance metrics are derived theoretically to establish an optimization problem that reveals the trade-off between communication and sensing. Furthermore, numerical simulations demonstrate the simultaneous communication and sensing abilities of LFM-CPM and reveal its superiority over other constant-modulus signal.