  In this paper, we propose a novel secure random caching scheme for
large-scale multi-antenna heterogeneous wireless networks, where the base
stations (BSs) deliver randomly cached confidential contents to the legitimate
users in the presence of passive eavesdroppers as well as active jammers. In
order to safeguard the content delivery, we consider that the BSs transmits the
artificial noise together with the useful signals. By using tools from
stochastic geometry, we first analyze the average reliable transmission
probability (RTP) and the average confidential transmission probability (CTP),
which take both the impact of the eavesdroppers and the impact of the jammers
into consideration. We further provide tight upper and lower bounds on the
average RTP. These analytical results enable us to obtain rich insights into
the behaviors of the average RTP and the average CTP with respect to key system
parameters. Moreover, we optimize the caching distribution of the files to
maximize the average RTP of the system, while satisfying the constraints on the
caching size and the average CTP. Through numerical results, we show that our
proposed secure random caching scheme can effectively boost the secrecy
performance of the system compared to the existing solutions.
