Resumen
The low-power wide-area network (LPWAN) paradigm is gradually gaining market acceptance. In particular, three prominent LPWAN technologies are emerging at the moment: LoRaWAN? and SigFox?, which operate on unlicensed frequency bands, and NB-IoT, operating on licensed frequency bands. This paper deals with LoRaWAN?, and has the aim of describing a particularly interesting feature provided by the latest LoRaWAN? specification?often neglected in the literature?i.e., the roaming capability between different operators of LoRaWAN? networks, across the same country or even different countries. Recalling that LoRaWAN? devices do not have a subscriber identification module (SIM) like cellular network terminals, at a first glance the implementation of roaming in LoRaWAN? networks could seem intricate. The contribution of this paper consists in explaining the principles behind the implementation of a global LoRaWAN network, with particular focus on how to cope with the lack of the SIM in the architecture and how to realize roaming.