An apparatus includes a downlink signal differentiating unit is configured to receive a downlink signal and differentiate a type of the downlink signal. A public baseband processing unit is connected to the downlink signal differentiating unit and is configured to receive a public downlink signal obtained by the downlink signal differentiating unit by the differentiating, to encode and modulate the public downlink signal to obtain a public baseband signal, and to transmit the public baseband signal to a carrier unit. A traffic baseband processing unit is connected to the downlink signal differentiating unit, and is configured to receive a traffic downlink signal obtained by the downlink signal differentiating unit by the differentiating, to encode and modulate the traffic downlink signal to obtain a traffic baseband signal, and to transmit the traffic baseband signal to the carrier unit.