Confidential Spatial Multiplexing in the Presence of Eavesdropper

In this paper, we present a confidential spatial multiplexing scheme in the presence of an eavesdropper, when the number of antennas at the source is less than that at the intended destination. To degrade the eavesdropper´s channel, a pre-coded interference is added to the message at the source. The interference power at the intended destination is minimized via least square solution while it cannot be removed at the eavesdropper, thereby disabling a reliable reception of data at the eavesdropper. Secrecy capacity and the symbol error rate at the intended destination and the eavesdropper are analyzed.