## 3 Materials and Methods
### Interference and Network Optimization Difficulties
#### 3.9.3 Optimization Challenges in 5G Networks  
5G is presented as a developed environment with an ecosystem where the boundaries are complete cities. 5G technologies promise high-speed and low-latency data transmission using the millimeter band. Although this frequency band allows these advantages, it only allows short distances. By allowing such short distances, problems such as interference become apparent. The optimization of this type of network should always be used to get the best out of it. In 5G, techniques such as MIMO and beamforming are used to reduce interference or signal degradation [90]. It should be noted that optimizations for 5G networks include different architectures that are part of this type of network. These architectures can be divided into non-standalone and standalone. Optimizing these architectures, depending on their niche, can be profitable, as the communication varies. Communication can be more accessible or restricted depending on the architecture. At the same time, different modulations can be obtained to enhance data transmission, transmission speed, and latency. In the same way, with 5G, most of the architectures allow the incorporation of MIMO. Thanks to beamforming management, it is possible to optimize the use of frequencies for transmission so that some technologies can send information in the mmWaves range. From interference in the case of NR, other interferences negatively affect the data transmission in this architecture due to the nature of this architecture. These are inter-carrier interference and phase interference. This is because it uses the mmWave frequency range. In turn, another interference that damages NR is numerology interference [97]. The evolution of mobile networks from 3G to 4G and now to 5G has significantly impacted the services and Internet of Things devices. Each new generation has provided faster data transfer speeds, increased bandwidth, and improved reliability, enabling the emergence of new services and applications that were previously not possible on mobile devices. As 5G networks become more widely adopted, they will continue to unlock new opportunities for innovation, transforming the way we interact with our devices and the world around us. Table 5 shows the impact of each mobile generation starting with 3G and explains the impact in an IoT context. New technologies and recent research about wireless communication have created new ways to transmit and receive data. With the evolution of technology such as 5G, new features arrived to provide/perform the ways to send and receive data. IoT has shown more benefits, helping with other technologies such as machine learning, cloud computing, and others. Since the data can be processed, each device forms a swarm intelligence that allows automatization and avoids wasting resources in the industry. Another factor in analyzing is the interference with the channels, since our houses, offices, and even natural places have electronic devices that typically use the 2.4 GHz band, which causes interference in this band. Therefore, 5G incorporates new bands to avoid the interference caused by this massive consumption of 2.4 GHz. We need to compare the features of 3G, 4G, and 5G to understand why 5G is an essential key in smart cities. The main technical characteristics of these three generations of technologies can be seen in Table 6.  
Table 7 presents the expectations for the use of 5G technology in the IoT. The first feature mentioned is bandwidth. Bandwidth refers to the amount of data that can be transmitted over a network or a communication channel in a given amount of time. In the context of 5G, higher bandwidth means that more data can be transmitted over the airwaves in a shorter period of time, which can result in faster and more reliable 5G