Enabling Pub/Sub over Low-Power Wide-Area Networks for the Internet of Things: design and implementation of the full IPv6/UDP/CoAP protocol stack

With the continuous growth of IoT applications, a new breed of wireless technologies has emerged, generically called Low-Power Wide Area Networks. Among these technologies we find LoRaWAN (Long-Range Wide Area Network), one of the most promising due to the open nature of the standard and developed by the LoRa Alliance. LoRaWAN is a media access control protocol, based on LoRa chirp-spread-spectrum modulation, which is a proprietary technology developed by Semtech. It is designed to operate on the unlicensed industrial, scientific and medical (ISM) radio bands and has the capability to reach a distance of several kilometers with data rates in the order of tens of Kbps. LoRaWAN's main characteristics include a power-optimized radio network, a simplified network topology, frame sizes in the order of tens of bytes transmitted a few times per day at ultra-low speeds and a mostly upstream transmission pattern. This allows the devices to spend most of their time in low-energy deep-sleep mode therefore enabling long battery lifetimes.\\ The main target of this research is to exploit the potential of this technology and enhance the interoperability between LoRa nodes and the Internet, by enabling CoAP communications between end-devices and remote clients. More specifically, the system is implemented according to the pubsub paradigm, where the figure of "broker" is introduced to allow store-and-forward messaging. The rationale behind this decision is that it spouses well with the LoRaWAN characteristics, since it allows the nodes to sleep between operations and favours uplink trasmissions. What is more the use of CoAP pubsub drastically simplifies the mote behavior, allowing it to only take the client role and shifting all the complexity of the server role to the broker. \\ To achieve the purpose the entire IPv6/UDP/CoAP stack is implemented, with particular focus on compressing the headers at each layer, in order to reduce the packet size at its minimum. The user is eventually provided with an API that allows him/her to easily expose LoRa motes as CoAP resources, hiding all the underlying technology that has been implemented. \\ As a conclusion an evaluation of the many advantages the compression brings is reported, as well as an analysis of the benefits introduced by the API, in a real-life scenario