Secure MIMO Communications in a System with Equal Numbers of Transmit and Receive Antennas

Secure communications in a multiple input multiple output (MIMO) system in which the eavesdropper\´s channel is inherently superior to that of the legitimate receiver is described. Both the legitimate receiver and the eavesdropper are assumed to have equal knowledge and comparable computational capabilities and there is no "secret key" known only to the legitimate receiver. The combination of artificial noise added at the transmitter, parallelization of the legitimate channel using the singular value decomposition, and low density parity check (LDPC) codes can overcome the superiority of the eavesdropper\´s channel and enable secure communications. The effectiveness of the method is greater for larger numbers of antennas and larger modulation constellations.