A signal processing method, wherein the method comprises: receiving an optical signal in a target receive channel, and converting the optical signal into an electrical signal; and determining, in the converted electrical signal, an electrical signal, wherein the determining of the electrical signal in the converted electrical signal comprises determining the electrical signal corresponding to a non-overlapping frequency band between the target receive channel and another channel, wherein the another channel is a channel that overlaps the target receive channel; and in that the method further comprises determining, based on the electrical signal corresponding to the non-overlapping frequency band, an electrical signal corresponding to a valid received optical signal that does not comprise an interfering optical signal in the target receive channel, wherein the interfering optical signal comprises a reflected interfering optical signal on the another channel, which is a target transmit channel that overlaps the target receive channel, characterized in that the valid received optical signal is a single-sideband optical signal, the reflected interfering optical signal is a double-sideband optical signal, a part of a frequency band of the target transmit channel overlaps the target receive channel, and the part of the frequency band is a frequency band between a central frequency and any edge frequency of the target transmit channel, wherein the determining, based on the electrical signal corresponding to the non-overlapping frequency band, an electrical signal corresponding to a valid received optical signal that does not comprise an interfering optical signal in the target receive channel comprises: determining a conjugate electrical signal of the electrical signal corresponding to the non-overlapping frequency band; determining an electrical signal corresponding to an overlapping frequency band between the target receive channel and the target transmit channel; and determining a difference between the electrical signal corresponding to the overlapping frequency band and the conjugate electrical signal as the electrical signal corresponding to the valid received optical signal that does not comprise the reflected interfering optical signal in the target receive channel. receiving an optical signal in a target receive channel, and converting the optical signal into an electrical signal; and determining, in the converted electrical signal, an electrical signal, wherein the determining of the electrical signal in the converted electrical signal comprises determining the electrical signal corresponding to a non-overlapping frequency band between the target receive channel and another channel, wherein the another channel is a channel that overlaps the target receive channel; and in that the method further comprises determining, based on the electrical signal corresponding to the non-overlapping frequency band, an electrical signal corresponding to a valid received optical signal that does not comprise an interfering optical signal in the target receive channel, wherein the interfering optical signal comprises a reflected interfering optical signal on the another channel, which is a target transmit channel that overlaps the target receive channel, characterized in that the valid received optical signal is a single-sideband optical signal, the reflected interfering optical signal is a double-sideband optical signal, a part of a frequency band of the target transmit channel overlaps the target receive channel, and the part of the frequency band is a frequency band between a central frequency and any edge frequency of the target transmit channel, wherein the determining, based on the electrical signal corresponding to the non-overlapping frequency band, an electrical signal corresponding to a valid received optical signal that does not comprise an interfering optical signal in the target receive channel comprises: determining a conjugate electrical signal of the electrical signal corresponding to the non-overlapping frequency band; determining an electrical signal corresponding to an overlapping frequency band between the target receive channel and the target transmit channel; and determining a difference between the electrical signal corresponding to the overlapping frequency band and the conjugate electrical signal as the electrical signal corresponding to the valid received optical signal that does not comprise the reflected interfering optical signal in the target receive channel. determining a conjugate electrical signal of the electrical signal corresponding to the non-overlapping frequency band; determining an electrical signal corresponding to an overlapping frequency band between the target receive channel and the target transmit channel; and determining a difference between the electrical signal corresponding to the overlapping frequency band and the conjugate electrical signal as the electrical signal corresponding to the valid received optical signal that does not comprise the reflected interfering optical signal in the target receive channel.