Time-correlated MISO wiretap channel with delayed CSIT

We consider the time-correlated multiple-input single-output (MISO) wiretap channel where a multi-antenna transmitter wishes to convey a confidential message to its receiver in the presence of an eavesdropper. Assuming that the transmitter with delayed channel state information acquires some knowledge on current channel state due to the temporal correlation, the secrecy degrees of freedom (SDoF), capturing the behavior of the secrecy capacity in high signal-to-noise ratio regime, is studied. We characterize the optimal SDoF and provide the achievable scheme that takes advantage of both spatial precoding and digitalized artificial noise alignment.