# Smart City Pilot Projects Using LoRa and IEEE802.15.4 Technologies
## 6 Conclusions  
In this paper, two important applications envisioned in smart city scenarios have been addressed: public smart lighting and building-monitoring. The former has been discussed showing that, thanks to the regular layout of street light poles, usually at short distance one to the other, a mesh topology using IEEE 802.15.4 at PHY and MAC layers could be adopted, jointly with the cellular network, to grant the connectivity to all of them, even in the case of thousands of nodes deployed in a wide area. Not only does the paper show the feasibility of such a solution (providing the technical details) but it also gives an insight into the relevant benefits in terms of power and money savings (\(-76\%\) and \(-73\%\), respectively, in the real world-case represented by the Italian municipality of Montechhiaurgolo).  
In the case of the building-monitoring application, instead, a star network topology has been considered, which is more suited to a scenario in which the nodes layout could be so irregular that in many cases nodes \"do not see\" each others, thus preventing the possibility of clustering.  
In this case, the long-range LoRa technology has been taken into account and it has been experimentally shown that its maximum coverage in a dense urban environment is in the order of 1-2 km, which is well below the 15 km claimed by LoRa manufacturers and vendors. Remarkably, this result has been obtained in very favorable conditions, with the gateway placed at a height of 71 m above the ground and the highest possible spreading factor. Therefore, it is expected that the coverage could be even lower when such conditions cannot be granted. Moreover, this paper showed how to tune the spreading factor adopted by the transmitter, in order to maximize the packet success rate in multipoint-to-point communications. Results demonstrate that, in order to cover an entire district, it will be requested to deploy multiple LoRa gateways, or to equip the gateway with multiple receivers, working on different channels and using different spreading factors.  
Future work: The two testbeds discussed in this paper are based on distinct wireless networks, expressly deployed for the specific services. In the next future, however, 4G cellular networks will also support the NB-IoT technology, which will be assigned a given amount of LTE resource blocks. In Italy, for instance, the LTE networks of the main operators will be enhanced with NB-IoT by the end of 2018. There is no guarantee that NB-IoT will outperform currently available short-range and long-range technologies; its introduction, however, will certainly change the IoT scenario in urban environments, as 4G networks are widespread, reliable and supported by big, in some cases supranational, operators.  
Motivated by these considerations, we believe that future research activities in the field of urban-IoT for smart cities should pay proper attention to NB-IoT, which is candidate to become the de facto standard for machine-to-machine communications.  
This work was supported by COST Action CA15104-IRACON. The authors would like to thank Wi4B self for supporting the implementation of the LoRa testbed and for providing the details of the smart lighting infrastructure in Montechiaurgolo. The authors would like to thank also [PERSON] for its contribution to the measurement campaign.  
[PERSON], [PERSON], [PERSON] and [PERSON] conceived the smart lighting platform and collaborated with Wi4B to its development. [PERSON], [PERSON] and [PERSON] have been and are currently involved in the Rigers project and they developed the LoRa simulator.