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37.4.2.3 Challenges
ОглавлениеIn general, the propagation of RF signals in indoor environments faces several challenges. Certain materials in the indoor environment affect the propagation of RF waves. For example, materials such as wood or concrete attenuate RF signals, while materials such as metals or water cause reflections, scattering, and diffraction of RF waves. These effects lead to multipath radio wave propagation, which prevents accurate calculation of the distance between the transmitter and the receiver in indoor environments. The propagation of RF waves is also affected by changes to the physical indoor environment (e.g. movement of people, rearrangement of furniture, structural modifications). In these environments, the RF properties are highly dynamic, and a radio map captured at a certain point in time cannot be used reliably for localization without accounting for these dynamic changes [12]. Moreover, while some solutions operate within a reserved radio band [18], most solutions utilize open spectrum bands. This means that these solutions must account for the increased risk of interference due to other systems sharing the same frequency bands of the radio spectrum. The usage of radio transmitting devices is also restricted in some cases, for example, in critical areas of most healthcare facilities, according to recommendations made by the Association for the Advancement of Medical Instrumentation (AAMI) [20] and other standards or regulatory bodies. Such restrictions limit the deployment of localization systems based on non‐broadcast RF waves.