Improving Secrecy Performance via Device-to-Device Jamming in Cellular Networks

In this paper, we study the secrecy performance of a cellular network, where a device-to-device (D2D) communication shares the spectral resources with a multi-antenna base station (BS). By assuming known the channel state information (CSI) of the legitimate user and using the maximal ratio transmission (MRT) at the BS, we first derive a closed-form expression of the ergodic secrecy capacity (ESC) for the wiretap channel as well as the ergodic capacity (EC) for the D2D link. Then, we present a simple yet efficient power allocation scheme to maximize the secrecy performance while satisfying the D2D transmission requirement. Finally, numerical results are given to demonstrate the merit of our study, concluding that the interference from the D2D communication can be exploited as a friendly jammer to enhance the security transmission in cellular networks.