Resource Optimization Framework for Physical Layer Security of Dual-Hop Multi-Carrier Decode and Forward Relay Networks

Physical layer security (PLS) is an emerging area for information security against eavesdroppers (Eve). Information security of any system can also be improved by using friendly jammers that produce interference signals to Eve. Traditional security techniques are limited by the processing power of the wireless nodes, whereas PLS can achieve communication secrecy without requiring computationally expensive cryptographic operations. The relay networks have emerged as a promising technology to enhance the performance of the wireless systems. This paper proposes a joint resource optimization framework for the PLS of dual-hop decode and forward (DF) relay network with and without cooperative jamming. In particular, the proposed framework consists of a base station (BS), multiple users, DF relays, multiple subcarriers, and an Eve. Our objective is to maximize the sum secrecy rate (SR) through optimal power loading over different subcarriers at BS and relay nodes, and efficient subcarrier assignment. We formulate a mixed binary integer programing problem for secrecy optimization and adopt Lagrangian dual method to achieve the efficient solutions. We also provide three benchmark frameworks, i.e., joint power optimization with random subcarrier assignment, equal power allocation with efficient subcarrier assignment and equal power with random subcarrier assignment to guage the performance of our joint resource optimization framework. Simulation results unveil that the proposed joint resource optimization framework under cooperative jamming and without jamming performs significantly better than the benchmark frameworks.