Effect of Interfering Transmitter on the Secrecy of Diffusive Molecular Timing Channels

This paper investigates the information-theoretic security of multi-particle diffusive molecular timing (DMT) channels for noise-limited and interference-limited scenarios. By utilizing a channel capacity upper bound expression, we obtain the secrecy outage probability (SOP), average secrecy outage rate (ASOR), and average secrecy outage duration (ASOD) expressions when the number of molecules arriving at Eve from Alice and Interferer follows Gaussian distribution. Subsequently, the effect of various channel parameters, such as Lévy noise parameter, molecular degradation, and molecular correlation on various secrecy metrics, is studied for both scenarios. In the noise-limited system, increasing molecular degradation leads to secrecy compromisation, with an increase in SOP and ASOD and a simultaneous decrease in ASOR. We also observe a significant improvement in the system’s secrecy, especially in terms of ASOR, on increasing the Lévy noise parameter. Concurrently, we analyze the channel parameter’s effect on the secrecy of the interference-limited scenario. From the ASOR and ASOD perspectives, we find that with increasing molecular degradation and correlation, the information-theoretic security of the system increases. However, increasing the Lévy noise parameter negatively impacts the system’s secrecy. Finally, extending our analysis to a three-dimensional environment reveals that additional dimensions lead to secrecy deterioration for the noise-limited and interference-limited cases.