# Design and Implementation of a Mixed IoT LPWAN Network Architecture
## 5 Case Study and Testing Environment
An ulterior analysis of the location of the water-meters, showed that samples received from those below the quartile 25% come mostly from devices placed in basements of buildings, which suggests that the missing-values are mainly associated with the fact that the radio signal has not enough power  
Figure 21: Number of samples received via radio (169 MHz ISM band) from 78 counters randomly selected from different areas of the city. to pass through the structure of the building. Samples from water-meters between the quartiles of 25% and 75% present a greater diversity associated with their origin. Some are located in basements, with perhaps better radio coverage and others are located on ground floors or entrances to residential homes in the open, suggesting that they may be located in'shadowed' reception areas due to the fact that they are in an urban environment in which radio coverage can present a certain variability. It is important to highlight that the company carries out a periodic campaign in which qualified personnel write down 'in situ' the consumption data indicated by the water-meter. Therefore, so for billing purposes this loss of samples does not influence the generation of the invoice for the customer and has no economic impact in what is charged as a service by the distribution company. However, these data losses do influence the strategic and operational areas of the company, not only because it implies that it is necessary to maintain a person dedicated to a manual inspection, but it also makes impossible to estimate the consumption habits of some users. This could be possible with no transmission losses due to the fact that although the current water-meters are configured to send a sample every hour, the sampling time could be reduced up to 15 min. A case study has been designed in which 5 buildings have been selected from the set with water-meters with a sample reception rate less than 25%, 3 buildings with water-meters located in critical areas (25%-75%) and 3 buildings located in the acceptable zones. In these buildings, in parallel with the current company water-meter based on the 169 MHz ISM Band, a prototype of each class (Sigfox, LoRaWAN and LoRa-Sigfox Gateway) has been placed. The LoRa-Sigfox Gateway device has been placed at the light yard of the buildings. A total amount of 33 acquisition prototypes have been deployed: 11 Sigfox, 11 LoRaWAN and 11 LoRa-Sigfox Gateway. In parallel, a 169 MHz ISM-based monitoring device has been left in order to compare transmission data rates coming from those currently used by the company with the transmission rates associated with each developed prototype. The results after 10 consecutive monitoring days are described below. Figure 22 shows a graph with the samples received during a period of 10 days (which theoretically it should be equivalent to an amount of 240 received samples) by each of the different acquisition devices placed in one of the buildings associated with one of the so-called 'alarming' water-meters (Q1 < 25%). This water meter is located in the basement of a residential building. The X axis indicates the number of the sample associated with the time at which it was acquired (values between 1 and 240 for the 10-day evaluation period with a sampling time of one hour) and the Y axis indicates the value (litres) measured by the water meter and transmitted by the acquisition device. This figure shows that according to the 'critical' classification previously indicated, the samples received with the device operating at the 169 MHz ISM Band, instead of the expected 240, is only 56, which means a reception rate of 25%. With the Sigfox prototype, an improvement in the reception rate is achieved, reaching the 134 samples received (55.8%). The LoRaWAN prototype receives 213 samples (88.8%) during the period. The LoRaWAN base station is located closer to the water-meter placement than the Sigfox station, whose location is determined by the official network operator for the city of Cartagena.