LPI/LPD communication systems

An apparatus, comprising:

• a processor;
• and
• a non-transitory computer-readable memory communicatively coupled to the processor, the memory including a set of instructions stored thereon and executable by the processor for:
• determining a decoy data signal vector used in a precoded signal in a transmission received from a transmitter;
• determining a secret key from an estimated channel matrix H;
• and
• decrypting a message embedded in the precoded signal, wherein decrypting comprises removing the decoy data signal vector and channel distortions from the precoded signal.

An apparatus, comprising:

• a processor;
• and a non-transitory computer-readable memory communicatively coupled to the processor, the memory including a set of instructions stored thereon and executable by the processor for:
• producing a decoy data signal vector for transmission;
• generating a MIMO precoding matrix from a data signal and channel state information;
• employing the MIMO precoding matrix to precode the decoy data signal vector to produce a precoded signal to be transmitted;
• and
• multiplexing a reference signal with the precoded signal to produce a multiplexed signal to be transmitted to a receiver, wherein the receiver employs channel estimates and the reference signal to decrypt the precoded signal.