Critical infrastructure, which includes facilities necessary for the normal functioning of society (e.g., power plants, transportation hubs, hospitals, etc.), requires reliable communication to ensure uninterrupted operation and coordination of actions in emergency situations. This paper presents a methodology for measuring and improving the quality of voice communication via VoWi-Fi and VoLTE technologies at critical infrastructure facilities. One of the key aspects of the methodology is the creation of a test environment that reflects the real working conditions at critical infrastructure facilities. This includes using devices that support VoWi-Fi and VoLTE technologies, setting up Wi-Fi networks and mobile Internet access, and selecting standard test scenarios to assess voice quality. An important part of the methodology is measuring various communication quality parameters, such as signal strength, delay, and packet loss. For this purpose, special measurement tools are used, including the Ping Monitor and G-NetWi-Fi apps on the Android platform. The obtained data allow us to objectively assess the effectiveness of VoWi-Fi and VoLTE technologies at critical infrastructure facilities, in particular, using the proposed MOS (Mean Opinion Score) metric. It has been established that one of the main disadvantages of the traditional approach to using VoWi-Fi and VoLTE is the lack of automatic switching between these technologies in the event of a deterioration in the quality of one of them, which can lead to unsatisfactory perception of the conversation by the user. The proposed methodology involves the use of a MOS metric monitoring system that continuously measures the quality of voice communication on both technologies and implements a mechanism for adaptive switching between VoLTE and VoWi-Fi. This allows for automatic switching to the optimal technology depending on current conditions and provides the best quality of service for the user. In general, the article provides important information for implementing and optimizing these technologies at critical infrastructure facilities to improve the reliability and efficiency of voice communications.
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