# A Comprehensive Study of the Use of LoRa in the Development of Smart Cities
## 4 Results of the Analysis of the Selected Works
### Analysis of the Network and Transport Capabilities
#### 4.2.2 Coverage of LoRa in IoT Applications  
LoRa's coverage can be measured on the basis of different parameters, such as received signal strength level (RSSI), signal-to-noise ratio (SNR), and packet delivery ate (PDR). SNR is an indicator of the link quality with respect to a radio channel's environmental parameters [57]. IoT applications in smart city require different coverage areas depending on the type applications, location of the sensors, and type of communication, i.e., point-to-point or central-gateway connections. These aspects are mainly associated with the design requirements of the application. Table 7 presents an overview of the type of coverage for each subcategory of smart city applications. On the basis of our quality assessment, healthcare applications consider a fixed communication between a diagnostic system and a base station, but there are also some applications, e.g., those focused on patient follow-up, which require signal quality during communication when the objects are in movement (the speed of a patient can be in the ranges of 1-3 km/h, 5-8 km/h, and 1-30 km/h) [58]. In the case of traffic control or transportation applications, the monitoring of streetlight systems requires communication among multiple nodes located within a short range. The optimal distance between streets light is around of 35 meters [52]. The RSSI value can be used to determine the location of the user in parking systems through the use of iBeacon [40]. If the RSSI value is high, then the user is considered to be close to a parking slot. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Data Rate** & **Spread Factor** & **Bandwidth (KHz)** & **Throughput (bps)** & **Payload (Bytes)** \\ \hline DR13 & SF7 & 500 & 21,900 & 230 \\ DR12 & SF8 & 500 & 12,500 & 230 \\ DR11 & SF9 & 500 & 7000 & 230 \\ DR10 & SF10 & 500 & 3900 & 230 \\ DR9 & SF11 & 500 & 1760 & 117 \\ DR8 & SF12 & 500 & 980 & 41 \\ DR4 & SF8 & 500 & 12,500 & 250 \\ DR3 & SF7 & 125 & 5470 & 250 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: LoRa parameters in US902-928 and AU915-928 bands, frequency of 915 MHz [56]. Figure 13: Relation among data frame, spread factor (SF), and bandwidth [56]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Data Rate** & **Spread Factor** & **Bandwidth (KHz)** & **Throughput (bps)** & **Payload (Bytes)** \\ \hline DR6 & SF7 & 250 & 11,000 & 230 \\ DR5 & SF7 & 125 & 5470 & 230 \\ DR4 & SF8 & 125 & 3125 & 230 \\ DR3 & SF9 & 125 & 1760 & 123 \\ DR2 & SF10 & 125 & 980 & 59 \\ DR1 & SF11 & 125 & 440 & 59 \\ DR0 & SF12 & 125 & 250 & 59 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: LoRa parameters in EU868, EU433, CN470, and AS923 bands, frequency of 868 MHz [56]. Table 8 shows an overview of signals parameters related to IoT applications for different smart city subcategories. In agriculture, the communication is generally between server and nodes, and the nodes are commonly fixed objects. These types of applications require to consider different issues such as obstacles, foliage of trees, geography of the field, and climate conditions. Healthcare applications require communication between diagnostic nodes and a base station. Both objects in this scenario are at a fixed location. In other cases like tracking of patients, it is necessary to communicate with objects in movement. In this scenario, multipath fading and Doppler effects are more relevant. In traffic applications, RSSI is used for detecting parking slot occupancy. The difference between RSSI values is used to know when a vehicle is arriving at or leaving a spot. The RSSI changes are more pronounced in nearby slots. An RSSI exceeding \(-90\) dBm is an indication of the occurrence of a transient event. Indoor coverage values higher than \(-70\) dBm are considered acceptable. On the other hand, for outdoor coverage, the power of LoRa signals can be affected by obstacles on the line of sight; in this scenarios, values higher than \(-100\) dBm are considered of good quality [31].