## 6 Conclusions  
The aim of this paper was to demonstrate the feasibility of a fully interoperable LoRaWAN-NB-IoT network, allowing for transparent interconnection among edge nodes regardless of the specific communication channel. A network infrastructure integrating LoRaWAN End Devices, NB-IoT Nodes and NB-IoT-powered LoRaWAN Gateways was set up and validated. In particular, three different scenarios were tested, according to the different channel configurations. These included a scenario where NB-IoT was employed for packet forwarding from LoRaWAN Gateways to the Servers, while the other two scenarios were designed to test peer-to-peer connection among nodes or subnetworks. In the first case, a direct NB-IoT connection among nodes was tested, while the last scenario focused on a hybrid bidirectional channel encompassing LoRaWAN and NB-IoT nodes. Moreover, the power consumption of the LoRaWAN-NB-IoT Gateway, in terms of current draw, was compared with the one of a LoRaWAN-4G Gateway. Such a test showed that little difference between the two solution can be noticed. However, this does not directly mean that the multi-protocol Gateway of this paper fails from the point of view of a low power feature. Indeed, it is still a prototype, contrary to the LoRaWAN-4G one, thus hinting at the fact that there is still room for improvement and optimisation from the point of view of power consumption. Such a claim is reasonable due to the power-saving policies that an NB-IoT facility implements with respect to standard cellular technologies such as 4G. Therefore, it is rational to assert that an NB-IoT Internet connection can be culled in favor of 4G since it entails smaller running costs compared with other cellular technologies.  
In all the aforementioned cases, the network demonstrated its operation, depending on the actual performances of the two technologies. Indeed, packet loss and latency were chosen as metrics for the evaluation of the system performances. Nonetheless, based the obvious dependence of performances on NB-IoT coverage and on quality of the equipment  
Figure 10: Gateways current consumption test results: (**a**) LoRaWAN-NB-IoT Gateway; (**b**) LoRaWAN-4G Gateway.  
(e.g., characteristics of the gateway components, hardware and software bugs, etc.), it is reasonable to deem that such results are useful to provide readers with a flavour of network capability and reliability. The positively achieved outputs throughout the tests suggest the feasibility of large-scale network deployments of this kind of infrastructure. These may be applied in a huge number of application scenarios where edge devices feature different requirements. Similarly, such a combination of technologies may lead to the definition of novel network topologies as well as of new protocols for the implementation of energy-management strategies.  
[PERSON] and [PERSON] conceived and designed the overall architecture; [PERSON] developed the network components; [PERSON] sorted out the tests; [PERSON] carried out data analysis; [PERSON] and [PERSON] wrote the paper. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The data presented in this study are available from the corresponding author upon request.  
The authors declare no conflict of interest.