## 6 Future Challenges  
Despite the evolution of smart campuses and universities in the last years thanks to the technological advances achieved in fields like IoT, cloud computing, and certain communications paradigms, future university planners, IoT vendors, and developers will still face relevant challenges in the following areas. * Scalability. As a campus can cover a large area, where a large number of users can request smart services, it is essential for applications to be easily scalable in order to adapt its performance to the number of simultaneous users. * Service flexibility. A smart campus/university should be able to provide multiple services, which may differ depending on the physical area where they are provided (e.g., depending on the faculty), on the specific user that request them (e.g., access privileges may differ between a student and a professor), or on the specific goal (e.g., advancing to more effective teaching and learning services may differ substantially from the design of smart environment applications). * Long-distance low-power communications. Since campuses usually cover areas of thousands of square meters that often involve monitoring outdoor smart IoT objects (e.g., street lights, irrigation systems), it is key to consider in the smart campus architecture the use of long-distance \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Reference** & **Smart Campus** &
\begin{tabular}{c} **Communications** \\ **Technologies** \\ \end{tabular} & **Network Planning** \\ \hline
[32] &
\begin{tabular}{c} Northwestern Polytechnical \\ University \\ \end{tabular} & Wi-Fi, Bluetooth & No \\ \hline
[33] & Birmingham City University & - & No \\ \hline
[35] & \
\begin{tabular}{c} University of Washington \\ Bothell \\ \end{tabular} &
\begin{tabular}{c} Zigbee, BLE, \\ 6 LowPAN \\ \end{tabular} & No \\ \hline
[36] &
\begin{tabular}{c} University of Business and \\ Technology of Birmingham \\ \end{tabular} & - & No \\ \hline
[10] & Tennessee State University & - & No \\ \hline
[37] &
\begin{tabular}{c} IMDEA Networks Institute \\ Wi-Fi, Bluetooth \\ \end{tabular} & No \\ \hline
[38] & University of Oradea & 4G, Zigbee & No \\ \hline
[43] & - & MESH Wi-Fi & No \\ \hline
[44] & - & Wi-Fi & No \\ \hline
[45] & - & 3G/4G/5G, Wi-Fi & No \\ \hline
[64] & Smart CEI Moncloa & Wi-Fi, Ethernet & No \\ \hline
[65] & \
\begin{tabular}{c} Wuhan University of \\ Technology \\ \end{tabular} &
\begin{tabular}{c} Cable, wireless, \\ 3G/4G \\ \end{tabular} & No \\ \hline
[66] & West Texas A\&M University &
\begin{tabular}{c} LoRAWAN, \\ 4G/LTE \\ \end{tabular} & No \\ \hline
[67] & Sapienza smart campus & - & No \\ \hline
[68] &
\begin{tabular}{c} Wisdom Campus, Soochow \\ University \\ \end{tabular} & - & No \\ \hline
[69] & Indian Institute of Science & sub-GHz radios & No \\ \hline
[70] & University of A Coruña & LoRaWAN & Yes (based on 3D-ray launching) \\ \hline
[154] & \begin{tabular}{c} Universitas Indonesia \\ \end{tabular} & \
\begin{tabular}{c} 800 MHz, 2.3 GHz, \\ and 38 GHz \\ \end{tabular} &
\begin{tabular}{c} Based on ray-tracing and \\ physical optic near-to-far field \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Communications technologies of the most relevant smart campuses solutions. wireless communications technologies whose energy consumption should be as low as possible to maximize IoT node battery life. * New communications technologies. Although this article has analyzed the currently most relevant communications technologies, smart campus designers should be aware of the latest advances on communications in order to include them in the designed architecture. For instance, some authors are already suggesting potential applications for 6G technologies [155; 156]. * Blockchain integration. DLTs like blockchain can be really useful to guarantee operational efficiency, data transparency, authenticity, and security.