# Research on Location Selection Model of 5G Micro Base Station Based on Smart Street Lighting System
## 4 Location Selection Model of 5G Micro Base Station
### Location Selection Model Construction
#### 4.2.2 Location Selection Index  
In order to meet the optimal location selection principle, three location selection indexes, including the combined ratio, the coupling ratio, and the unification ratio, were proposed to measure the degree of cooperation between the equipment according to the correlation between the equipment mounted on the light poles in the actual project. The combined ratio is the basis for evaluating the location selection index, and only when the equipment is mounted on the same light pole can the coupling and unification ability analysis be carried out. (1) Combined ratio \(\alpha_{\mathrm{h}}\)  
In the site selection, to meet the basic coverage requirements of the target equipment, such as the strict coverage regulations of operators for 5G micro base stations, some of the devices may not be able to be carried on street light poles, and new poles need to be built separately. From the perspective of system integration, it is hoped that more and more street light poles can carry target equipment, which can save costs, reduce the number of individually built poles, and contribute to improving the city's image. Therefore, the combined ratio index \(\alpha_{\mathrm{h}}\) is proposed to measure the integration degree of the mounted equipment at the physical level. The \"combined\" is defined as the equipment that can be installed on the street light pole without the need to build a new pole, provided that the primary site selection requirements are met. The calculation formula is as follows:  
\[\alpha_{\mathrm{h}}=\frac{\delta_{\mathrm{h}}}{g_{\mathrm{c}}} \tag{1}\]  
where \(g_{\mathrm{h}}\) is the number of target devices that can be combined; \(g_{\mathrm{c}}\) is the number of target devices. (2) Coupling ratio \(\alpha_{\mathrm{m}}\)  
Based on equipment combination, the coupling relationship between target and installed equipment is considered to achieve the synergistic effect among subsystems. The coupling relationship is defined as whether two devices mounted on the same light pole can generate higher-value capabilities than when the devices work independently, thus improving service efficiency and reducing service costs. For example, 5G micro base stations and various sensors are coupled devices, and the former can meet the high transmission rate demand of sensors for communication well. Traffic cameras can determine the high-risk behaviors of vehicles and display them on the LED display to provide warnings for following vehicles. The light pole carrying the device with a coupling relationship with the target device was defined as the coupling pole, and its proportion in the light pole was a signification factor in measuring the coupling capability. The coupling rate \(\alpha_{\mathrm{m}}\) depends \begin{table}
\begin{tabular}{c l} \hline \hline
**Notations** & **Descriptions** \\ \hline \(\alpha_{\mathrm{h}}\) & The combined ratio, the proportion of devices installed on light poles \\ \(\alpha_{\mathrm{m}}\) & The coupling ratio, the percentage of coupling pole \\ \(\alpha_{t}\) & The unification ratio, the proportion of uniformity before and after site selection \\ \(\gamma\) & The coverage rate, the percentage of area covered by target devices \\  & The difficulty coefficient, the ratio of the target area to the light pole coverage area \\ \(F_{\mathrm{a}}\) & The combining capacity, measuring the combining capability \\ \(F_{\mathrm{b}}\) & The coupling capacity, measuring the coupling capability \\ \(F_{\mathrm{c}}\) & The unification capability, measuring the unification capability \\ \(F\) & The subsystem coordination capability, measuring the coordination capability \\ \(F^{\prime}\) & The subsystem coordination degree, measuring the coordination degree \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Frequently used notations throughout this paper.