We demonstrate a seamless fiber–wireless system in the W-band using optical self-heterodyne method for up-conversion of an optical signal to a millimeter-wave signal at 100 GHz. We transmit a high-spectral efficiency 64-quadrature amplitude modulation orthogonal frequency division-multiplexing signal over the system and achieve a transmission capacity of approximately 100 Gb/s over a single channel. We evaluate the performance of the system with and without using a power amplifier at the antenna site and confirm that the nonlinear distortion of the amplifier significantly degrades the signal performance. The proposed system is promising for high-capacity, low-latency, and low-power consumption mobile transport and access networks in beyond 5G era.