We theoretically and experimentally analyzed the principle of frequency quadruple optical millimeter-wave generation utilizing phase modulator along with an intensity modulator based on optical carrier suppression (OCS) scheme. In the experiment,40 GHz optical millimeter wave (mm-wave) is generated by adjusting the bias of intensity modulator and the phase between the two modulators which are driven by 10 GHz radio frequency signal. 2.5 Gb/s baseband data is modulated on 40 GHz optical mm-wave directly and transmitted to the base station over standard single-mode fiber (SMF-28). The experimental results show that the power penalty of downlink data signals which are transmitted over 20 km SMF-28 is less than 0.8 dBm. The eye diagram of the baseband signal is still clear. This scheme simplifies the radio-over-fiber system and mm-wave signals are stable and reliable.