Abstract: The present disclosure provides a signal processing apparatus and a signal processing method, the signal processing apparatus includes: a preprocessing unit configured to generate a joint matrix according to channel matrixes of subcarriers, and perform a parallel-to-serial conversion on QAM signals of the subcarriers to obtain a serial QAM signal; a judgment unit configured to determine a constraint relationship of a constellation point in each element according to a determining result obtained by determining that whether the constellation point is to be extended in a constellation diagram; a processing unit configured to establish a convex optimization model according to the joint matrix, the serial QAM signal and the determining result, and determine a joint time-domain signal of antenna channels according to the constraint relationship of the constellation point and the convex optimization model; and a conversion unit configured to perform a serial-to-parallel conversion on the joint time-domain signal.