“…The PM problem minimized the transmit power given the SINR requirement [8]- [13], [15], [16], [28], and its optimal solution could be scaled to that of the SINR balancing problem [28], which targeted to maximize the minimum SINR while satisfying the transmit power constraint [5], [9], [14], [16], [26], [27]. Moreover, [29] investigated the MMSE problem that minimizes the mean square error (MSE) between the received signal and the expected signal located in CIR, based on which an SLP scheme was proposed to achieve significant performance with low complexity. Furthermore, the SINR balancing and MMSEbased SLP schemes have been proven to be the generalizations of ZF precoding and MMSE precoding [5], [14], [29], respectively.…”