Securing Wireless Communications with Energy Harvesting and Multi-antenna Diversity

This paper proposes a secure wireless communication system that integrates Physical Layer Security (PLS) with Energy Harvesting (EH) to improve both data confidentiality and network sustainability. The system model consists of a source node S, powered by energy harvested from spatially distributed power stations, a multi-antenna destination node D, and an eavesdropper node E located within the communication range. A time-switching protocol enables the source node S to alternate between energy harvesting and secure data transmission. To enhance signal quality and system security, the destination node D employs Selection Combining (SC) and Maximal Ratio Combining (MRC) techniques to mitigate fading effects and eavesdropping risks. Analytical expressions for the Signal-to-Noise Ratios (SNRs) at both the destination D and the eavesdropper E are derived, along with the Probability Density Function (PDF) and Cumulative Distribution Function (CDF) of these SNRs under block Rayleigh fading conditions. Furthermore, an exact analytical formulation for Secrecy Outage Probability (SOP) is presented, quantifying the probability of information leakage under various system configurations. The proposed model is validated through extensive Monte Carlo simulations, which confirm the accuracy of the mathematical analysis of SOP. Based on simulation results, the impact of key system parameters—such as energy harvesting efficiency η, time-switching protocol parameter α, the number of antennas M at the destination node, and the number of beacon nodes N—on SOP is analyzed. The results provide valuable insights for optimizing secure and energy-efficient communication in wireless networks.