Date Added: Aug 2009
This paper studies the use of artificial interference in reducing the likelihood that a confidential message transmitted between two multi-antenna nodes is intercepted by a passive eavesdropper. A portion of the transmit power is used to broadcast the information signal with just enough power to guarantee a certain data rate for the intended receiver, and the remainder of the power is used to broadcast artificial noise in order to mask the desired signal from a potential eavesdropper. The interference is designed to be orthogonal to the multiple-stream information signal when it reaches the desired receiver. A modified water-filling algorithm is proposed that balances the required transmit power with the number of spatial dimensions available for jamming the eavesdropper.