This study discusses two key technologies used in radio-over-fiber (RoF) systems, namely, the generation and transmission of millimeter-wave signals and optical modulation schemes capable of carrying vector signal formats and utilizing the continuous performance improvements offered by digital signal processing. A cost-effective frequency-quadrupling technique capable of generating millimeter-wave signals up to 72 GHz is proposed. The generated optical millimeter-wave signals have very high quality, with an optical carrier and harmonic distortion suppression ratio exceeding 36 dB. An optical modulation scheme that can support a 64-QAM, 16 Gbits/s orthogonal frequency-division multiplexing RoF system is also demonstrated. Results of this study demon-strate that both methods offer realistic solutions to support future wireless systems.