Quantum Computing Resistant Secure Communication Over Modified Nakagami‐q Fading Wireless Channel

Quantum computing threatens traditional encryption methods like RSA and ECC, as quantum algorithms such as Shor's algorithm can break them efficiently. Physical Layer Security (PLS) offers a resilient alternative by leveraging the inherent properties of communication channels, making it immune to quantum advancements. This paper investigates the secrecy capacity of modified Nakagami‐ q fading channels in the presence of a multi‐antenna eavesdropper. The multiple antennas at the receivers are assumed to be independent and identically distributed (i.i.d.). We apply a small limit argument approximation (SLAA) to the zeroth‐order modified Bessel function of the first kind within the conventional Nakagami‐ q probability density function. This modification eliminates the mathematical intractability associated with the Bessel function, enabling the derivation of novel, simple, and closed‐form analytical expressions for key secrecy metrics. Specifically, we derive and analyze the probability of positive secrecy capacity, secure outage probability, and ergodic secrecy capacity. The validity of the proposed approximation is confirmed through high‐fidelity Monte Carlo simulations ( samples), which demonstrate a negligible Root Mean Square Error (RMSE) of from the conventional model. Results show that the system maintains positive secrecy capacity even when the eavesdropper has a higher SNR than the legitimate channel, particularly in low‐SNR regions where eavesdropper antenna count has minimal impact. Special cases, such as Rayleigh fading with single‐antenna setups, further validate these findings. This research highlights the robustness of PLS in protecting communications against quantum threats and provides a mathematically tractable framework for secrecy analysis in generalized fading environments. © 2026 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.