## 2 Radio Communication Technologies  
Various communication technologies have been developed depending on the deployment characteristics and requirements of the IoT use cases. While establishing efficient radio technologies for IoT connectivity, it is important to highlight the end-to-end use case factor in IoT-based networks, as every two nodes need to be connected. IoT connections are generally classified into three categories based on the use cases. The current networks used include 2G, 3G, LTE, and WiFi, which cover the first and second classes, while the third classes requires smarter approaches to IoT connections. A \"smarter\" approach includes catering for low device power consumption, supporting a huge number of connections, and decreasing the costs for the end units or modems. Short- and medium-range wireless protocols such as Bluetooth, WiFi, and ZigBee are range- and power-restricted, so they are not an ideal fit for IoT applications. Additionally, traditional long-range wireless protocols usually have strict power requirements that are not suitable for battery-powered devices [5]. The need for low-power and wide-area networks (LPWANs) to connect massive numbers of sensors with battery lives ranging from 5 to 10 years and modules, enabling low-cost, long-range coverage, has led to the third class of connectivity (Figure 1). The third class or LPWAN has evolved the IoT development process and is available as licensed and unlicensed bands. Figure 1: Comparison of wireless communication technologies. LPWAN technologies consume less battery power while working over long ranges. LPWAN is rapidly becoming the leader in the field. Strategic analyses and predictions indicate that network operators could make over $13 billion from LPWAN connectivity and from the additional service profits related to data analytics and security support. The numbers say the most, and the connectivity revenue of LPWAN technologies increased to $7.5 billion in 2022 [4]. LPWAN technologies have evolved with the characteristics below [6]:  
* **Very low power consumption--**Having 50 million IoT-connected devices that consume a huge amount of energy will lead to environmental catastrophes and is not economic. For this reason, over 10 years of optimized battery life for smart parking, smart environment, and smart home devices is a must for LPWAN connections;
* **Brief messaging--**LPWAN systems have optimized solutions for messaging within the length of an SMS;
* **Decreased device costs--**The economic approach enables the connection of each module at the cost of a few dollars;
* **Outdoors and indoors coverage--**As IoT nodes are mainly integrated sensors, it is necessary to support their connectivity in rural locations, underground, in walls, and in building basements;
* **Easy network installation--**In some cases, the use of LPWAN has made the reuse of existing cellular components possible;
* **Scalability--**Connecting large numbers of devices over wide geographic areas is another smart characteristic of IoT communication technologies. As can be seen in Figure 2, LPWAN technologies are divided into two subgroups:
* The 3 rd Generation Partnership Project (3 GPP)-licensed technologies, including **NB-IoT** (narrowband IoT) standardized by the 3 GPP standards body, LTE-MTC (LTE-machine-type Communication), and EC-GSM-IoT (extended-coverage GSM-IoT), with capabilities to support existing cellular networks in LPWA (low-power, wide-area) IoT applications;
* Non-3 GPP-based technologies (**unlicensed technologies**):
* or low-range, wide-area network, an intended networking protocol for wireless battery-operated devices that was promoted by the Alliance of LoRa;
* **Sigfox**, a global propriety-based technology (founded in 2010 by [PERSON] and [PERSON], Labgee, France) that was one of the first promoters of LPWAN.