SECRECY CAPACITY IN AN ALTERNATE RELAYING WIRELESS NETWORK WITH SUPERPOSITION CODING AND SUCCESSIVE DECODING

Abstract

The broadcasting characteristics of radio channels pose security vulnerabilities in wireless communication networks. This thesis explores the implementation of physical layer security (PLS) within cooperative relaying systems by considering the physical properties of the communication channel and signal decoding strategies. In the analyzed network with successive relaying and superposition coding, from the perspective of the desired destination, the capacity of wireless channels is improved through i) simultaneous spectrum utilization by a source and two half-duplex relays and ii) optimization of transmitted signal parameters targeting the destination. From the perspective of the eavesdropper, its location and detection strategies may adversely affect the ability to decode the transmitted information. Specifically, the signals transmitted by relays, designed to help the destination, will interfere with the decoding by the eavesdropper and are considered a form of artificial noise (AN). Using simulations in different propagation environments, it is demonstrated in this thesis that the destination can receive information securely with varying levels of bandwidth efficiency, except for very limited regions of the eavesdropper's positions.