Embodiments of the present invention disclose a signal processing method, apparatus, and system, where the method includes: receiving a downlink signal that carries an uplink signal; and performing first interference cancellation on the uplink signal by using an estimated self-interference signal, so that a remaining amount of interference of the uplink signal is less than a first interference threshold, thereby minimizing out-of-band interference of the uplink signal on the downlink signal without using a plurality of radio frequency front-ends or without using a duplexer on a same radio frequency front-end. In the embodiments of the present invention, no duplexer is adopted, and therefore, difficulty and a cost of base station and system layout can be reduced, and extra energy consumption of a mobile terminal can also be reduced.