Trustworthy Slotted ALOHA

Meeting the ever-increasing demands for trustworthy wireless communication is crucial in modern networks. In this letter, we investigate physical layer security in a slotted ALOHA scheme with randomly distributed users. Specifically, we evaluate a system where users are randomly distributed in a ring around the base station (BS), while eavesdroppers are distributed in rings around them. We propose that legitimate users allocate a fraction of their transmit power to generate artificial noise (AN) to increase the probability of secure transmission. To evaluate the performance of the proposed trustworthy slotted ALOHA scheme, we introduce a new metric called secrecy outage rate and derive a closed-form expression for this metric, which involves the outage probability at both the BS and the eavesdropper. Simulation results validate the theoretical analysis and demonstrate the superiority of the proposed scheme over a benchmark scheme without AN, as well as the usefulness of the proposed metric.