Communication of IoT devices using LoRa protocol

Broj IoT-uređaja u svijetu, i potreba za njihovim umrežavanjem svakodnevno raste. Mogu se primijeniti na raznim područjima primjerice u kućanstvu, za održavanja gradova, u zdravstvu itd.\\ Cilj im je automatizirati ponavljajuće zadatake i/ili donositi odluke o obavljanju zadataka, primjerice navodnjavanja, temeljem očitanja senzora iz njihove okoline. Ključ dobrog rada takvog "pametnog" sustava je usklađena komunikacija svih potrebnih uređaja. Parametri te komunikacije i mogućnosti uređaja utječu na odabir protokola. Ovaj rad promatra LoRa protokol koji služi za komunikaciju IoT-uređaja s niskom potrošnjom energije, otpornu na smetnje, na udaljenostima do 14 km. LoRa podržava spajanje uređaja u topologiju zvijezde čime jedan uređaj dobiva ulogu MASTER čvora dok su ostali definirani kao END čvorovi koji se svaki zasebno uparuju s MASTER uređajem.\\ Pločice Clicker 2 i 4 \textit{for} STM32 međusobno komuniciraju pomoću LoRa modula s antenom za prijenos poruka koji se postavlja na Clicker-e. Komunikacija putem LoRa protokola je sigurna jer su poruke kriptirane AES128 algoritmom simetričnog kriptiranja, MIC broj štiti integritet poruka, a otporne su i na vremenske uvjete što zadovoljava i sigurnosni kriterij raspoloživosti.The number of IoT devices in the world, and the need for their networking, is growing every day. They can be applied in various areas such as households, city maintenance, healthcare, etc. \\Their goal is to automate repetitive tasks and/or make decisions about task execution, for example, irrigation based on sensor readings from their environment. The key to the successful operation of such a 'smart' system is the coordinated communication of all necessary devices. The parameters of this communication and the capabilities of the devices influence the choice of the communication protocol. This paper examines the LoRa protocol, which is used for low-power, interference-resistant communication of IoT devices over distances of up to 14 km. LoRa supports device connectivity in a star topology, where one device assumes the role of a MASTER node, while the others are defined as END nodes that, each, pair with the MASTER device. The Clicker 2 and 4 boards for STM32 communicate with each other using LoRa modules with message transmission antennas, which are installed on the Clickers. Communication via the LoRa protocol is secure because messages are encrypted using the AES128 symmetric encryption algorithm, the MIC number is ensuring message integrity, and they are also resilient to weather conditions, meeting the availability security criterion