5G mobile communication systems 5g mobile communication Artificial intelligence Bit error rate Broadband Communication Broadband networks Communications systems Cost effectiveness Digital signal processing Direct-detection Equalizers Heterogeneous communication Heterogeneous communication system Mobile communications Nonlinear equalizer Nonlinear optics Optical fibers Optical signal processing Optical signal-processing Orthogonal frequency division multiplexing Radio-over-fiber Radio-over-fibers Tera Hertz Terahertz communication Wireless communications broadband communication direct detection heterogeneous communication system nonlinear equalizer radio-over-fiber