IoT and Telecommunication Networks
The Internet of Things (IoT) constitutes the communication network of a variety of devices, home appliances, cars, and any other object that incorporates electronic media, software, sensors, actuators and network connectivity, and allows data connection and exchange. Simply put, the philosophy of IoT is to connect all electronic devices to one another (local area network) and / or to the internet (world wide web) creating Wireless Sensor-Actuator Networks (WSANs). Its operating network layer incorporates a fusion of public and private networks such as Local Area Networks - LAN (Bluetooth, Zigbee, WiFi), Cellular Networks (GSM, 3G, 4G, 5G) and recently Low Power Wide Area Networks - LPWAN (LoRa, Sigfox, NB-IoT) and Satellite Networks (VSAT). The choice of the mixture of various networks intends to achievea communication level of certain quality and reliability taking also into account the security need concerning the transmitted data (Wei & Lv, 2019; The Things Network, 2019).
LPWAN is more suitable for IoT application since each device needs to transfer a very small amount of data in long range, as shown in Fig. 1. The three most popular LPWAN technologies, have arisen at global level are, Sigfox, LoRa, and NB-IoT, which involve many technical and functional differences. The most important of them are the range (up to 40 km for Sigfox, 20 km for LoRa, 10 km for NB-IoT), the power consumption, where LoRa technology is the winning one, and the business model of operation, where LoRa is a public network, Sigfox is a private network, albeit both are using unlicensed bands and NB-IoT is operated by cell carrier companies on licensed bands (21b).As far as the topology is concerned, LoRa and Sigfox technologies need to connect to agateway, which uses high bandwidth networks such as WiFi, Ethernet or Cellular in order to connect to corresponding server, implementing a star-of-stars topology in which gateways relay messages between end-devices and a central network server (The Things Network, 2019;LoRa Alliance, 2019).
Figure 1. Required data rate vs. range capacity of radio communication technologies: LPWAN positioning (Mekki, Bajic, Chaxel & Meyer, 2019)