Enabling dual-polarized, dual-vector millimeter-wave transmission via delta sigma modulation in a single-input single-output wireless link

Radio-over-fiber (RoF) systems have attracted much attention in the field of wireless communication because of their advantages of high bandwidth, low loss and long-distance transmission. Utilizing delta–sigma modulation (DSM) and optical and antenna polarization multiplexing, we propose a novel scheme for the generation, transmission, and detection of dual-polarized, dual-vector millimeter-wave (mm-wave) signals via a single-input single-output (SISO) wireless link. Our method leverages band-pass (BP) DSM to transform high-order quadrature amplitude modulation (QAM) signals into simple on-off keying (OOK) signals. Subsequently, these signals undergo optical quadrature phase-shift keying (QPSK) modulation, optical polarization multiplexing, and optical heterodyne beating, producing dual-polarized, dual-vector mm-wave signals. These signals are then transmitted through an antenna-polarization-multiplexing-enabled SISO wireless link and reverted to their original QAM format by receiver digital signal processing (DSP). Experimental validation confirms the effectiveness of our proposed scheme. Our proposed scheme enables the generation of dual-polarized, dual-vector mm-wave signals in the W-band (75–110 GHz). These signals carry both 64QAM and 128QAM data in each polarization, over 10 km standard single-mode fiber-28 (SMF-28) and a 1 m SISO wireless link, achieving the bit error rates (BERs) of all signals below the hard-decision forward-error-correction (HD-FEC) threshold of 3.8e−3. Based on BP DSM, this scheme significantly enhances the performance of RoF systems by reducing receiver sensitivity requirements. Besides, by introducing optical and antenna polarization multiplexing simultaneously, the capacity and efficiency of the RoF system are significantly improved.