Performance analysis with and without torch node in secure communications

In this paper, we present secure communication system with torch nodes. With a channel state information (CSI) between source and eavesdropper, a Alice null the received signal for eavesdropper with zero forcing beamforming (ZFB). But the CSI between source and eavesdropper is hard to achieve in secure communication. In this work, we propose the torch node in secure communication. The torch is assist node for secure communication that only report the CSI between source and the torch node. And we consider that the CSI of the torch node and some of eavesdroppers that close to torch node has a correlation. With this assumption, the Alice improve the secure outage with the CSI from the torch node. The study show that when transmit antennas of source is many then torch node bring the transmit power gain.