On secrecy outage capacity of fading channels under relaxed delay constraints

We consider information theoretic secrecy over flat fading channels under relaxed delay constraints. More specifically, we extend the definition of outage secrecy capacity for single-input single-output single-eavesdropper case (SISOSE) to account for relaxed delay constraints, and study the fundamental limits under two different assumptions on the transmitter CSI (channel state information). First, we provide bounds on secrecy outage capacity with k+1 block delay constraint. We show that the bounds are tight for several special cases. We also provide a weaker lower bound that is easier to compute, and show that under low SNR, delay constraint has significant impact on secrecy outage capacity. The analysis serves as an important step towards complete characterization of information theoretic security with delay and outage constraints.