IEEE Open Journal of the Communications Society
Improving Secrecy Capacity in the Face of Eavesdropping in SWIPT CIoT Networks With Actor-Critic DRL
Nada Abdel Khalek, Walaa Hamouda
Abstract
One of the key enablers of 6th-generation (6G) wireless networks is cognitive radio, offering optimized spectrum utilization, enhanced device intelligence, and improved security. This article investigates secure communication in an energy-harvesting (EH) cognitive Internet of Things (CIoT) network operating over cascaded fading channels. Here, a CIoT transmitter employs an intelligent strategy to allocate time for simultaneous wireless information and power transfer (SWIPT) and transmission power to maximize the secrecy rate. The CIoT receiver operates in full-duplex (FD) mode, receiving confidential messages while simultaneously emitting cooperative jamming signals to disrupt an eavesdropper. We formulate the challenging non-convex optimization problem to maximize secrecy capacity while ensuring spectrum sharing and energy constraints and model the CIoT agent’s decision-making as a model-free Markov decision process (MDP). We then propose a deep reinforcement learning (DRL) approach to determine the optimal strategy for secure transmission and resource allocation. Specifically, we derive the instantaneous secrecy rate and employ a deep deterministic policy gradient (DDPG) algorithm with a lightweight actor-critic architecture to efficiently address dynamic channel occupancy, EH opportunities, and fading conditions. The proposed DDPG algorithm allows the CIoT agent to adapt to dynamic environments, enhance transmission security, and extend network lifetime without prior knowledge. Extensive simulations confirm its convergence and effectiveness in improving secrecy capacity, throughput, and energy efficiency. Moreover, the results attest to its superior performance compared to existing benchmarks.