Secure Communication with Beamforming and Jamming in Time-Varying Channels

For secured transmission over wireless channels, a beamforming technique of information and jamming signals based on channel state information is considered. By beamforming and splitting the transmission power for both sending information to the target receiver and interfering the eavesdroppers, the secured communication can be achieved. Because the beamforming vectors for information and jamming signals are calculated with channel information of the target receiver, the channel variation can cause the loss of the expected secrecy rate. In this paper, this rate loss is analyzed in high signal to noise ratio (SNR) region. It is verified that the analyzed upper bound behaves similarly the exact one with respect to both SNR and mobile speed with a constant gap.