A Spectrum-Efficient MoF Architecture for Joint Sensing and Communication in B5G Based on Polarization Interleaving and Polarization-Insensitive Filtering

The intelligentization of future society puts forward an urgent demand for high-precision sensing and ultra-high-speed wireless communications in the upcoming beyond fifth-generation (B5G) era. We propose and experimentally demonstrate a novel spectrum-efficient MMW-over-fiber (MoF) architecture for joint sensing and communication in B5G optical-wireless converged networks. The proposed MoF architecture is based on polarization interleaving and polarization-insensitive filtering. In the proposed architecture, the sensing and communication sidebands are generated simultaneously through asymmetrical single-sideband (ASSB) modulation, whereas the two local oscillator (LO) sidebands up-converting the sensing and communication signals to MMW band are obtained by carrier-suppressed double-sideband (CS-DSB) modulation. By interleaving the two sets of sidebands for sensing and communication in two orthogonal polarizations, the demand for higher bandwidth devices and the occupied spectral grid can thus be effectively reduced. The ASSB modulation eliminates the chromatic-dispersion- (CD) induced power fading for long-reach services. The polarization-insensitive filtering removes the need for complicated polarization tracking, resulting in a simple structure at the remote units (RUs) and polarization-free digital signal processing (DSP) at the user ends (UEs). Moreover, the two sets of sidebands originate from a shared laser, so frequency offset estimation (FOE) can be avoided to further reduce the complexity and power consumption of the DSP, thereby facilitating a user-friendly terminal. The experimental results show that a ±15-mm ranging accuracy at B5G MMW band for single-target detection is achieved, and a 30-cm ranging resolution for dual-target detection is also realized. Furthermore, a 23-Gbit/s error-free transmission rate at 28GHz over 5.41-km single-mode fiber (SMF) and 2-m wireless distance is successfully demonstrated without frequency offset compensation.