# Design and Implementation of a Mixed IoT LPWAN Network Architecture
## 6 Conclusions  
This article has been focused on the design and implementation of a mixed IoT LPWAN network architecture with application for remote monitoring in urban environments, where shadowed areas associated radio coverage can arise. LPWAN is described as a promising technology that allows deployment of wide area and low power networks specific to IoT. In particular, the approach has been to concentrate on Sigfox and Lora technologies because they allow the deployment of a large number of connected objects at a low infrastructure costs. They offer long-range connectivity to cheap, battery-operated devices, which require the transmission of small amounts of data at regular intervals of time over a long lifespan. A set of mixed IoT LPWAN end-devices has been developed. Its design has been oriented to acquire water-meter consumption measurements. A mixed network architecture dedicated to ensure all acquired samples are transmitted and successfully received at the remote information system has been proposed too. A specific LoRa-Sigfox Gateway device has been designed and included in the proposed network. This device is capable of take advantage of the LoRa basis in order to have a strong signal capable of connect to an end-device located at places with bad coverage, and then transform the data in order to send it and connect in a transparent way with a Sigfox network, already deployed by an existing network operator that finally transmits data towards the final reception systems. A study case of a system architecture connected to a set of 11 different buildings located at places with different coverage levels has been performed. From the results obtained in this deployment it is possible to conclude that:  
* In locations where the coverage in the 169 MHz ISM band has a reception rate lower than 25%, it seems that a solution like the one described in the LoRa-Sigfox Gateway prototype allows an optimal reception rate (100%) to be ensured. The Sigfox or LoRaWAN technologies improve reception, but do not achieve 100% reception rate, probably due to losses in signal strength that avoids a good penetration towards the location of the water-meters. * In locations where the reception rate in the 169 MHz ISM band is ranged within 25% and 75%, the LoRa-Sigfox and LoRaWAN prototypes offer the best performance. This seems to indicate that communication with the Sigfox station, whose location is predetermined by the network operator in the area, sometimes does not have enough power to penetrate to the location of the water-meter. Therefore, it would be necessary to evaluate one of the following alternative solutions: (1) placing a private (owned by the water distribution company) LoRaWAN base station on a building's roof within the radius of action of the water-meters and then place a LoRaWAN acquisition device attached to in each water meter, or (2) a solution based on two devices, a LoRa-Sigfox Gateway acquisition device plus the Gateway itself placed at the light yard of the house, which transmits the signal to an area where there is suitable Sigfox connectivity and can communicate with the local network operator station. * In areas where the reception rate in the 169 MHz ISM band is greater than 75%, the three prototypes allow reaching a 100% reception rate. In this case, the most suitable solution seems to be the solution based on the Sigfox prototype, since it would not be necessary to deploy any additional base station, as is required by the solution based on the LoRaWAN prototype, and only one device is necessary, instead of the two devices (end device + gateway) associated with the solution based on the LoRa-Sigfox Gateway prototype. * An additional improvement over the solution given by the current device working in the 169 MHz ISM band is that the three prototypes developed can be configured to have a sampling rate up to 10 min, compared to the resolution limit of 15 min offered now by the ISM solution, thus improving not only the rate of reception, but also by expanding the resolution of the sampling.