Location-Based Beamforming for Enhancing Secrecy in Rician Wiretap Channels

We propose a new optimal location-based beamforming (LBB) scheme for the wiretap channel, where both the main channel and the eavesdropper's channel are subject to Rician fading. In our LBB scheme, the two key inputs are the location of the legitimate receiver and the location of the potential eavesdropper. Notably, our scheme does not require any channel state information of the main channel or the eavesdropper's channel being available at the transmitter. This makes our scheme easy to deploy in a host of application settings in which the location inputs are known. Our beamforming solution assumes a multiple-antenna transmitter and a multiple-antenna eavesdropper, and its aim is to maximize the physical layer security of the channel. To obtain our solution, we first derive the secrecy outage probability of the LBB scheme in an easy-to-evaluate expression that is valid for arbitrary real values of the Rician K-factors of the main channel and the eavesdropper's channel. Using this expression, we then determine the location-based beamformer solution that minimizes the secrecy outage probability. To assess the usefulness of our new scheme, and to quantify the value of the location information to physical layer security, we compare our scheme to other schemes, some of which do not utilize any location information. Our new beamformer solution provides optimal physical layer security for a wide range of location-based applications.