An uplink signal transmission method includes receiving, by an active antenna unit of a base station, a first uplink signal sent by a terminal in a first band. The method also includes sending, by the base station, the first uplink signal to a first baseband processing unit of the base station corresponding to a second band for demodulation. The active antenna unit of the base station includes a first array antenna corresponding to the first band and a second array antenna corresponding to the second band. The first band is lower than the second band.