Physical Layer Security for Multi-Antenna and Relay Systems

Physical layer security has gained a lot of interest in the past few years, due to the increasing importance of securing communication channels against jammers and eavesdroppers. In this proposed research project, we consider the problem of maximizing the secrecy rate of multi-antenna and relay systems with single or multiple eavesdroppers. We start by studying multiple antenna (MISO and MIMO) systems with eavesdroppers, where the transmitter and\or the receiver are equipped with multiple antennas. We consider solving the problem of maximizing the secrecy information rate, which is defined as the difference between the mutual information between the legitimate transmitter and receiver, and the mutual information between the legitimate transmitter and the eavesdropper. Using convex optimization tools, we will be looking for optimal and low complexity solutions for the beamforming\precoding vectors. These algorithms will be extended to massive MIMO systems where we have a large number of antennas at the legitimate nodes, and possibly a large number of eavesdroppers as well. Furthermore, we will consider relay systems, where in addition to the legitimate transmitter and receiver, there are some relays in the system that can help in increasing the secrecy rate. We will also consider optimizing the relaying strategy used at the relays and their transmit powers.