Secure communications with cooperative jamming: Optimal power allocation and secrecy outage analysis

摘要

This paper studies the secrecy rate maximization problem of a secure wirelesscommunication system, in the presence of multiple eavesdroppers. The securityof the communication link is enhanced through cooperative jamming, with thehelp of multiple jammers. First, a feasibility condition is derived to achievea positive secrecy rate at the destination. Then, we solve the original secrecyrate maximization problem, which is not convex in terms of power allocation atthe jammers. To circumvent this non-convexity, the achievable secrecy rate isapproximated for a given power allocation at the jammers and the approximatedproblem is formulated into a geometric programming one. Based on thisapproximation, an iterative algorithm has been developed to obtain the optimalpower allocation at the jammers. Next, we provide a bisection approach, basedon one-dimensional search, to validate the optimality of the proposedalgorithm. In addition, by assuming Rayleigh fading, the secrecy outageprobability (SOP) of the proposed cooperative jamming scheme is analyzed. Morespecifically, a single-integral form expression for SOP is derived for the mostgeneral case as well as a closed-form expression for the special case of twocooperative jammers and one eavesdropper. Simulation results have been providedto validate the convergence and the optimality of the proposed algorithm aswell as the theoretical derivations of the presented SOP analysis.