## 3 Materials and Methods
### Interference and Network Optimization Difficulties
#### 3.9.1 Interference
\begin{table}
\begin{tabular}{l c c c c c c} \hline \hline
**Interference Type** & **Coverage** & **Latency** & **Availability** & **Access** & **Modulation** & **Coding** \\ \hline Noise & Reduced & Increased & Reduced & Reduced & Reduced & Reduced \\ Multipath & Reduced & Increased & Reduced & Reduced & Reduced & Reduced \\ Inter-cell Interference & Reduced & Increased & Reduced & Reduced & Reduced & Reduced \\ Co-channel Interference & Reduced & Increased & Reduced & Reduced & Reduced & Reduced \\ Interference from other devices & Reduced & Increased & Reduced & Reduced & Reduced & Reduced \\ Jamming & Reduced & Increased & Reduced & Reduced & Reduced & Reduced \\ Interference from other wireless networks & Reduced & Increased & Reduced & Reduced & Reduced & Reduced \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Types of interference that impact 5G networks and IoTas said in [83], because of resource limitation within the network, due to the frequency reuse factor. In the same way, inter-cell interference is identified when a Base Station connects directly in the close range of another BS, and that is when there is a simultaneous transmission in that reuse. A distortion appears by the interference that gives the user and other equipment in the same cell. * Intra-Channel and Inter-Channel interference: Inter-channel interference usually occurs when there is a low power within the macro-cell network. Then, when communicating, the information is forwarded to the nearest base station. When the transmission is made, it is completed through fast switching and restricts delays and propagation losses. However, this produces intra-channel interference that affects the valuable signal. On the other hand, inter-channel interference occurs due to the physical proximity of the devices when two separate frequency bands cause interference with each other. As these devices operate in close range, the transmitter of a high-power signal interferes with the receiver of a weak signal. It is important to emphasize that 5G IoT networks or devices with channels in the MHz range are susceptible to this type of interference due to the proximity and number of nearby devices. One way to mitigate this type of interference is through spatial modulation via MIMO [84]. * Inter-Symbol Interference: Inter-symbol interference occurs when one or more symbols interfere with other symbols. It is caused by phase or amplitude dispersion in the channel, resulting in signal distortion. This can be seen in OFDMA, where multipath propagation occurs. One study [85] exposed how this type of interference can be an excellent challenge for network systems and should be sought to improve the efficiency of the bandwidth while seeking alternatives in the modulation. This is in order to counteract this type of interference. * Inter-numerology interference: Multiple numerology is a model to provide flexibility for devices in different services. For these numerologies, 15, 30, 60, 120, and 240 kHz channels are used. They aim to improve performance and significant bandwidth. As stated in [86], the authors introduce a non-orthogonality in the system, causing difficulties for symbol alignment in the time domain. When sampling at the same frequency, numerology tends to align differently, making synchronization within the frame difficult. This is known as interference between numerologies. * Cross-Link Interference: This interference occurs when signals are transmitted to neighboring cells in different directions simultaneously, either in time frequency or arbitrarily overlapping resources. As mentioned in [87], there are different types of interference and different ways in which it occurs. For example, the Base Station receives interference from user equipment devices in adjacent cells, or a downlink user equipment receives interference from a second database. * Inter Beam Interference: With the high demand for technological services, the aim has been to improve spectral efficiency and network performance.