Paper Title
Physical Layer Security Enhancement by Using Multiple Antennas

This paper treats a transmitted data security enhancement by physical layer transmission scheme in device-to- device (D2D) direct communications underlaying cellular networks. We assume that a D2D transmitter sends its data to a legitimate D2D receiver by reusing the frequency resources that are allocated to the cellular uplink transmission between a cellular user and a base station. We consider a wiretap channel where there is a single eavesdropper that attempts to overhear the D2D transmitted signal. In order to prevent the eavesdropper from decoding the D2D signal and to enhance the physical layer security, we propose to apply a precoding vector at the D2D transmitter. Through the simulation, we show that the secrecy capacity can be improved by applying the appropriate precoding vector at the D2D transmitter. Index Terms: Physical layer security, multiple antenna transmission, precoding, device-to-device communications, secrecy rate, eavesdropper, wiretap channel.