Linear MMSE transceiver optimization for general MIMO wiretap channels with QoS constraints

In this paper, we investigate the problem of jointly designing optimum linear precoder and decoder with secrecy constraints, where two legitimate parties communicate in the presence of an eavesdropper over multiple-input multiple-output (MIMO) Gaussian channels. In particular, we focus on optimizing the linear transceiver to guarantee a certain quality of service (QoS) level for the legitimate receiver in terms of mean square error (MSE), whilst employing the artificial noise to maximally degrade the MSE for the eavesdropper. We assume that the transmitter may not or may have the channel state information (CSI) for the eavesdropper, and then propose two design formulations. With the aid of majorization theory, we characterize the forms of optimal transmit precoder when both the legitimate receiver and the eavesdropper employ the optimal linear MMSE receiver. Numerical results illustrate main conclusions.