Key Words: Internet of Things; data transmission; communication protocols; big data.
Abstract. Communication models and protocols in Internet of Things (IoT) are relatively new field of research and use due to the fact, that connecting objects by digital means in Internet has occurred only in the last decade. However, the rapid grow of applications of this paradigm in almost all areas of human activity has led to enormous volume of data generated from all kind of sources (things) and transmitted all over the global digital network. This, in turn, has led to the creation of new models and protocols for data transmission in IoT. The paper gives an overview of the main approaches / models for communication in IoT. The requirement for scalability and simplicity is amongst the most important when IoT and Big data are involved. Four models are presented – the Push, Request/Response, Subscribe/Notify and Publish/Subscribe. A classification and layered approach is made for protocols used in IoT. Three of the most widely used for data transmission in IoT are taken for further investigation – MQTT, CoAP and AMQP. They are compared in terms of bandwidth, overhead, size of transmitted data, reliability and security. Then are compared with HTTP, which is well known and widely used on the Internet. The conclusions are that the most popular model for IoT and Big data communication is the Publish/Subscribe one, whether in regard to the use and recommendation for data protocol, one cannot point a clear leader at present (unlike the protocols in the TCP/IP stack for Internet), so there is the tendency that for the time being, different data protocols will be used in different IoT and Big data applications.