# Sigfox and LoRaWAN Datasets for Fingerprint Localization in Large Urban and Rural Areas
## 3 Collection Methodology
### Sigfox Rural  
As shown in Figure 1, the first dataset was collected in a large rural area between the cities of Antwerp and Ghent. This dataset contains 25,638 Sigfox messages which were received between 16 November 2017 and 5 February 2018, as indicated by the temporal spread graph in Figure 2. In order to collect these messages, ten _Sensolus Stickntrack_ devices [19], like the one in Figure 3, were carried by people who commute by car between the cities of Antwerp and Ghent on a daily basis. These devices contain a Ublox CAM-M8C GPS receiver, which obtains a GPS fix every ten minutes. A Sigfox message with GPS coordinates is sent directly after obtaining this GPS fix. Due to the fact that the total transmission time of a Sigfox message can take up to six seconds, the received coordinates of the transmitting device could differ from the actual device coordinates at receiving time. Therefore, the correlation between RSSI measurements and the received GPS coordinates could hold an additional GPS location estimation error of tens of meters, depending on the ground speed of the transmitting device. Additional information such as the ground speed of the device, or GPS signal quality measurements such as the Horizontal Dilution Of Precision (HDOP) could not be included in the message because of the limited Sigfox payload size.  
Figure 1: All messages in the rural Sigfox dataset were obtained in a large area between the cities of Antwerp and Ghent. Transmission locations are indicated by red dots on the map.  
After receiving a message from a Stickntrack device, a callback function in the Sigfox backend forwards a JSON string for every base station that received that message. Apart from the message payload, such a JSON string contains a message identifier, a base station identifier, the RSSI for that base station and the receiving time in ISO 8601 format. All these JSON strings are logged in a MongoDB database on a local data server. Afterwards, all entries in this raw database were grouped by their message identifier and receiving time in order to create a new database, where every entry represents a unique Sigfox message. Finally, this database was queried to extract all Sigfox messages in the rural area.  
Table 2 illustrates how these messages are stored in the rural Sigfox dataset. Every row represents one of the 25,638 unique messages in the dataset. The first 137 columns denote all base stations that were found in the rural area. If a message was received by a base station, the RSSI for that base station is filled in. For base stations that did not receive the message, an out of range RSSI of \(-200\) dB is inserted. This approach was based on the collection methodology for an indoor WiFi fingerprinting database, which was created by [PERSON] et al [8]. The last three columns of our rural Sigfox dataset depict the receiving time, latitude and longitude of the message.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**BS 1** & **BS 2** & **BS 3** &... & **BS 137** & **RX Time** & **Latitude** & **Longitude** \\ \hline \(-138\) & \(-200\) & \(-127\) &... & \(-200\) & 2018-02-04T16:18:42+00:00 & 51.0958362 & 4.1329538 \\ \(-200\) & \(-200\) & \(-200\) &... & \(-200\) & 2017-12-22T18:17:48+00:00 & 51.0121241 & 3.17136215 \\... &... &... &... &... &... &... &... \\ \hline \hline \end{tabular}
\end{table}
Table 2: The structure of the rural Sigfox dataset. Every row represents a Sigfox message and indicates its receiving base stations (BS), the receiving time of the message (RX Time) and the GPS coordinates at transmission time.  
Figure 3: The Sensolus Stickntrack device sends GPS coordinates over Sigfox every ten minutes [19].  
Figure 2: The rural Sigfox dataset holds 25,638 messages which were collected from 16 November 2017 to 5 February 2018. This figure illustrates the temporal spread of this dataset.