# Cognitive Radio Network Technology for IoT-Enabled Devices +
## 3 Cognitive Radio Network Based on IoT
### Internet of Things Definition  
Internet of Things (IoT) is a network of things connected to the Internet that can communicate via various communication protocols. Sensors and communication modules allow these objects to interact with the surroundings [13; 14; 15]. Pressure, proximity, humidity, and temperature sensors are among those sensors. Nowadays, the IoT connects the real and digital worlds. Things will interact and learn with IoT. The Internet of Things is going to affect every aspect of our lives, connecting our televisions, automobiles, smartphones, utility meters, heart monitors, thermostats, and virtually everything else we can think of. Several technologies and protocols, such as Wireless Sensor Networks, IPv6, IPv6 Low power Wireless Personal Area Networks (6 LoWPAN), Constrained Application Protocol (CoAP), and Cognitive Radio, have contributed to the development of the IoT since its conception at the end of the year of 1998 [16]. As a result of this shift, there are now more  
Figure 3: Machine learning for CR.  
app-development environments available online, and more compact, low-power devices, such as sensors and actuators, on the market. Limitations in size, cost, power, battery life, range, storage, processing, and data transfer are common among IoT gadgets. Connectivity in IoT networks is typically high, and the underlying protocols are simple [17]. The five layers of Figure 4 make up the IoT architecture [18; 19; 20]:  
* The radio frequency identification (RFID) tags, sensors, actuators, etc., that make up the physical world are represented by the Perception (or Recognition) layer. Data collection and transformation is the primary function. Some of them, like actuators, take a control signal and turn it into a predetermined motion;
* The primary function of the transmission (or network) layer is to send or receive control signals between the middleware layer and the perception layer via various networking technologies;
* The middleware is a software layer that processes the information it receives from the lower layers and makes decisions depending on the results;
* The IoT applications can be found in the application layer. It then uses that information to tailor its service offering to the end user;
* As well as the information gathered at the transport layer, the business layer gives system administrators command over the entire IoT infrastructure. It creates numerous types of company plans.  
It is anticipated that, by the year 2025, Internet of Things networks would include more than 50 billion connected heterogeneous items. Some examples of these devices include sensors, surveillance cameras, kitchen appliances, mobile phones, thermostats, utility meters, and nearly anything else. The requirement for reliable wireless communication will increase dramatically as a result of this expansion. A few examples of how the internet of things is already being integrated into day-to-day life include the smart grid, smart energy management, smart security, smart farming, smart transportation, smart housing, and smart cities [21; 22]. A significant barrier is presented by the scarcity of the available spectrum. In this study, we focus on this issue, which is a direct result of the proliferation of IoT devices and the consequent convergence of the cognitive radio paradigm.