## 5 Importance of Ubiquitous Cellular Coverage in Hospitals
### Proposed Solutions for Coverage Improvement  
**To address the challenges posed by coverage gaps, hospitals can adopt targeted solutions such as femtocells and distributed antenna systems (DAS). These technologies are designed to enhance indoor cellular coverage, ensuring reliable connectivity in all areas within CHUCB. **  
**Femtocells--Femtocells are small, low-power indoor base stations that provide localized cellular coverage. They are particularly effective in areas with high user density, such as wards, emergency rooms, and imaging departments. Femtocells can be deployed strategically to address coverage gaps without requiring extensive modifications to existing infrastructure. For example, installing femtocells in critical areas identified during the measurement campaign (e.g., points 13, 17, and 21) can significantly improve signal strength and reliability. In contrast to approaches focused exclusively on 5G networks, such as that proposed by [PERSON] et al. [25], our study advocates femtocell deployment as a more cost-effective and adaptable solution for hospital environments like CHUCB. Unlike 5G-only infrastructure, femtocells support multiple additional cellular technologies (e.g., LTE, UMTS, NB-IoT), aligning with the multi-technology signal environment observed in our measurements. Furthermore, this strategy is consistent with the recommendations of [PERSON] et al. [17], who emphasize the importance of scalable and economically viable solutions for healthcare facilities operating under budget constraints. By enabling localized coverage across heterogeneous radio access technologies, femtocells provide a practical balance between service quality and deployment costs. **  
**Distributed Antenna Systems (DAS)--DAS consists of multiple antennas distributed throughout a building, connected to a central base station. This system provides uniform coverage across large spaces, making it ideal for hospitals with complex layouts. While DAS is more expensive to install and maintain, it offers excellent scalability and can complement femtocells in areas with lower traffic density. Although their efficiency in terms of mobility and homogeneous coverage is recognized, their applicability in contexts with localized needs and limited budgets is less advantageous [26]. **  
**Hybrid Solutions--A combination of femtocells and DAS can be employed to optimize coverage. For instance, femtocells can be used in high-density areas, while DAS can cover transition zones or large open spaces [27; 28]. This hybrid approach ensures cost-efficient and technically robust coverage tailored to the specific needs of the hospital. **  
**The use of radiating cable, a technology traditionally applied in indoor coverage of specific environments, was also considered. However, in the particular context of the Centro Hospitalar Universitario Cova da Beira (CHUCB), its implementation faces substantial practical and operational barriers, compromising the feasibility of its adoption [29]. The installation of radiating cable presents considerable technical requirements, as it necessitates precise positioning to avoid contact with walls or metallic supports, which implies the use of specific support structures. The calibrated grooves along the cable, responsible for the gradual emission of the signal, must be appropriately oriented to prevent significant losses, making the installation process even more delicate. Additionally, this type of cable experiences progressive attenuation with increasing distance, requiring the use of amplifiers or segmentations [30]. This solution, nonetheless, proves particularly effective in linear environments, such as tunnels or long corridors [31]. Hence, despite its technical value in certain specialized scenarios, the application of radiating cable is not suitable for the punctual, dispersed, and localized coverage needs observed in the present study.