On Secrecy of Codebook-Based Transmission Beamforming under Receiver Limited Feedback

We investigate the secrecy performance of a codebook based transmission beamforming for a sensitive data link against passive eavesdropping. We characterize the secrecy outage probability of a communication link that is being eavesdropped. We consider a limited feedback scenario where the transmitter is using a predefined codebook known to both transmitter and receiver for beamforming, and analyze the secrecy outage probability of the link when it being eavesdropped. Our analysis also provides the secrecy outage probability of the beamforming transmission in the direction of the intended receiver. We characterize how the secrecy outage probability improves as the number of transmit antennas increases. We further analyze the effect of codebook design on secrecy enhancement and provide bounds on the secrecy outage probability of codebook beamforming.