# Enhancing Communication Security in Drones Using QRNG in Frequency Hopping Spread Spectrum
## 7 Evaluations
### Results and Observations  
Figure 5 presents a comprehensive overview of our proposed methodology for enhancing the security and reliability of multi-drone communications using QRNG-based FHSS systems. At the core of our approach is a QRNG device, which generates truly random numbers to drive the frequency hopping sequences. These random numbers are efficiently distributed to multiple drones through a shared memory system, ensuring that each drone has access to high-quality random data for its FHSS operations. To manage concurrent access to the QRNG device, we implement a specialized protocol that optimizes resource utilization while maintaining the integrity of the random number generation process. This architecture allows each drone to implement its own FHSS system using the shared random numbers, resulting in a network of secure, jam-resistant communication channels. The wireless medium, represented by the cloud in the diagram, emphasizes the challenging environment in which these secure communications take place. By integrating quantum randomness into a multi-drone FHSS framework, our methodology significantly enhances the system's resistance to jamming, interception, and other forms of interference, thereby improving the overall security and reliability of drone communications in complex operational scenarios. The experimental results, as illustrated in Figures 6-17, provide compelling evidence of the effectiveness of our QRNG-based frequency hopping system across multiple drones. The frequency distribution plots (Figures 7, 11 and 15) demonstrate a relatively uniform spread of frequencies for all three drones, except for the presence of jamming at 5500 Hz, indicating successful implementation of the quantum random number generation. The frequency sequence plots (Figures 8, 12 and 16) show no discernible patterns, which is crucial for maintaining unpredictability in the hopping sequence. Notably, the autocorrelation plots (Figures 6, 10 and 14) exhibit sharp peaks at zero lag and linear decay to near-zero values for all other lags, confirming a general absence of periodicity or predictability in the sequences, albeit some short-term correlation; which indicates that the RPU technology has still room for improvement in terms of quality and stability of the generated random numbers. The spectral analysis plots (Figures 9, 13 and 17) further corroborate these findings, showing a relatively flat power spectral density across frequencies, which is characteristic of truly random sequences. These results collectively demonstrate that our QRNG-based system successfully generates unique, largely unpredictable, and uniformly distributed frequency hopping sequences for each drone, thereby enhancing the security and reliability of the communication system against potential jamming or interception attempts. That being said, while QRNG technology is still at its early stage of development, it shows promising performance in the future advancement of secure communication scenarios. An important aspect of our experimental setup was the selection of parameters to thoroughly evaluate the performance and resilience of our QRNG-based FHSS system. Each drone generated a sequence of 10,000 frequency hops (\(\text{num\_hops}=10\),000), operating within a frequency range from 1000 Hz to 10,000 Hz (\(\text{freq\_min}=1000\) Hz, \(\text{freq\_max}=10\),000 Hz). The duration of each frequency hop was fixed at 0.01 s (\(\text{duration}=0.01\) s), resulting in a total communication time of 100 s per drone. To ensure synchronized operations, all drones were programmed to commence their frequency hopping sequences simultaneously, using a synchronization time set 10 s ahead of the current system time (\(\text{sync\_time}=\text{current time}+10\) s), as a proxy for GPS time. The jamming simulation was implemented by introducing interference at a central frequency of 5500 Hz.