## 5 Discussion  
The literature review yielded significant insights. Initially, an extended search of the literature and bibliography referring to the quite noteworthy and significant \"CI\" term was conducted in Google Scholar and Scopus. Using strict keyword criteria included in article titles and focusing on publications extending from 2019 to 2023, we obtained 1667 results from Scopus and 2610 from Google Scholar. However, when the definition \"WSN\" was added, the number of appropriate articles was drastically reduced. Scopus yielded only 144 and Google Scholar a mere 82. Further refining of the inquiry while including both \"CI\" and \"WSN\" terms via an AND function, either by being located in the title or included as official keywords in the paper's abstract sections, Scopus results diminished to 15, while Google Scholar provided a solitary result. In total, 22 referenced papers, including 17 journal articles and 7 conference papers, substantially support the idea of WSN implemented in CI sectors, contrary to the remaining published review papers that suffice to merely describe the topic and record the achievements of the scientific community referring to it. Such an outcome of the addressed literature indicated two research outcomes. First, many publications we studied require a thorough examination to ascertain their relevance to WSNs in CIs. On the other hand, it suggests that this research area, whilst blending WSNs with CIs, offers substantial scope for future exploration in a variety of directions. The literature search referring to the core sectors where CIs play a significant role is highlighted in Figure 5 and Table 2.  
It reveals that the most prevalent approach in the studied literature seems to be addressed generally and not specifically, which refers broadly to various sectors without an in-depth analysis of any specific area. The energy and transportation sectors emerge as the secondary focal points, while the more humanitarian sectors such as health and emergency/rescue services are low in preference. Regarding the range of use of wireless communication protocols and technologies implemented in CIs, as addressed in the referenced literature, their range of use is presented in Figure 6, where it is evident that cellular communication and ZigBee emerge as the most popular protocols, followed closely by LoRaWAN. Figure 5: Bibliography results of CI sectors. As stated in [41; 42], which address the water key sector, 4G communication technology is used, while 5G is implemented in the energy sector, as stated in [43], and in the transportation sector, as stated in [44]. In [66], 5G is generally addressed as a useful implementation in smart grids and intelligent transport systems and healthcare, medical, industrial, and manufacturing sectors on the whole. ZigBee, on the other hand, poses another application filed concerning the water sector, as outlined in [41; 42], and also the energy sector, as stated in [46; 47; 60]. LoRaWAN has a stake in the field of CI sectors such as the energy sector [47], health industrial transportation, industrial/manufacturing sectors [53], military, and emergency/ rescue services. LoRaWAN where Helium comes in place, as commented in [54; 55] and according to [66], is generally implemented in smart grids and intelligent transport systems and healthcare, medical, industrial, and manufacturing sectors. It is worth noting that communication standards are rarely mentioned in the referenced literature, merely in three conference papers, e.g., in [46] (where the IEEE 802.15.4 standard is addressed), in [50] (where 3 GPP is mentioned), and in [55] (where AES-128 is also mentioned). Two journal papers refer to communication standards, e.g., in [62] (where the routing protocol for low-power and lossy networks (RPL) is mentioned) and in [49] (where the ISO 37120, ISO 37122, ISO 37120, ISO 37123, ISO/IEC 27001:2017, n RDL 8/2011, and ISO 27002 protocols are mentioned).