AbstractIn the quasi‐millimeter radio access system, the links are installed radially from the central station (CS) to the outstation (OS). Therefore, the interference characteristics of the CS are deteriorated at the time of rain.This paper proposes a transmission power control method with a view to reducing the deterioration of the interference characteristics at the CS in rain. The effect of compensation of the level ratio of a desired wave to an undesired wave (D/U) degradation at the CS in the rain can be reduced by 11.5 dB by the transmission power control (TPC) of 20 dB. Further, the speed of the rain attenuation was found which is a propagation parameter needed for the TPC. The trailing speed of the rain attenuation in the proposed TPC algorithm is 67 dB/s, which is much larger than the maximum speed of the 3 dB/s of the rain attenuation. Hence, the proposed TPC algorithm can sufficiently follow the rain attenuation.