Secure On–Off Transmission in Slow Fading Wiretap Channel With Imperfect CSI

This paper investigates the slow fading single-antenna wiretap channel with imperfect channel state information (CSI) and studies an on-off transmission scheme with fixed communication rate, secrecy rate, and transmit power for maximizing the secrecy throughput under the constraints of secrecy outage probability (SOP) and reliability outage probability (ROP). We first solve this problem in a special case without ROP constraint for which the optimal secrecy throughput is obtained under SOP constraint. The result for the special case gives us an upper bound for the secrecy throughput with imperfect CSI. With the help of this special case, a general case with ROP constraint is studied. In this case, the problem is transformed into a one-dimensional (1-D) search problem on a finite interval, which can be solved either by the exhaustive 1-D search to obtain the optimal solution or by the golden search method (GSM) to obtain a suboptimal solution. Simulation results are finally presented to validate the theoretical analysis and show that the performance obtained by using the GSM based 1-D search is very close to that of exhaustive 1-D search.