Microwave Photonic Joint Radar, Wireless Communications, and Spectrum Sensing System With Broadband Tunability From 12 to 40 GHz

To address the demands for multifunctional integration in the Internet of Things (IoT) and the future Internet of Everything (IoE), we show a microwave photonic system that integrates radar, wireless communications, and spectrum sensing capabilities, featuring broadband tunability from 12 to 40 GHz. The proposed system utilizes a two-stage modulation scheme where two cascaded electro-optic modulators are employed: The first stage is used to generate two frequency-sweep optical sidebands, and the second stage is employed to further load the data onto the optical signal. After optical-to-electrical conversion, the joint radar and communication signal can be generated. Besides, one frequency-sweep optical sideband generated in the first stage is reused and modulated by the signal under test for spectrum sensing after interacting with a stimulated Brillouin scattering gain. The concept is experimentally verified. An amplitude-shift keying (ASK)-linearly frequency-modulated (LFM) signal with a radar bandwidth up to 8 GHz and broadband tunability from 12 to 40 GHz is generated for radar ranging with a ranging error within ±2 cm and a range resolution of 4.9 cm, while the ASK-LFM signal reaches a maximum data rate of 2 Gbit/s over 1.4-m free-space transmission. For spectrum sensing, by adjusting the pump frequency, the frequency measurement range spans from 0 to 40 GHz, with a frequency measurement error within ±20 MHz and a frequency resolution of around 200 MHz.