## 3 Materials and Methods
### Interference and Network Optimization Difficulties
#### 3.9.3 Optimization Challenges in 5G Networks
\begin{table}
\begin{tabular}{p{56.9 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Interference** & **Description** & **5G Impact** \\ \hline Intra-Channel and Inter-Channel interference & Intra-channel interference occurs when there is little power within the macro network cell. & Inter-channel interference occurs due to the proximity of devices when two separate frequencies cause interference. As they operate at short range, the transmitter of a high-power signal causes interference; interference can also be due to the exploration of hetnets with OFDM. There are ICI reduction solutions with reverse frequency allocation (RFA) employed, which is a proactive interference. & It is caused by phase or amplitude dispersion of the channel, which results in signal distortion. This can be clearly seen in OFDMA, which causes multipath propagation and impacts bandwidth efficiency. \\ \hline Inter-Numbering interference & Docurs when using the numerology system for greater flexibility and does not allow the alignment in the time domain to be perfect. These misalignments or imperfections are known as inter-numerology interference. & In the search for higher performance and significant bandwidth, using numerology, can cause interference by having networks with many devices sending significant amounts of information, which makes this type of interference more pronounced, affecting the network’s performance. \\ \hline Cross-Link Interference & This type of interference occurs when a transmission is made to a neighboring cell in different directions simultaneously, either by arbitrarily overlapping resources or by time frequency. & Cross-link interference can affect 5G networks due to the amount of BS required, since incorrect hopping can cause performance failures. \\ \hline Inter-Beam interference & This occurs when using MIMO technology, as this type of array sends RF energy in all directions, with the spatial division of the multiple beams causing interference. Adjacent beams cause this either by the same cell or by neighboring cells. & It causes interference in applications where MIMO antenna technology is introduced due to the same usage. When looking for better spectral efficiency and improvements in network performance, interference from adjacent beams within the same cell or multiple MIMO arrays may negatively influence their neighbors. \\ \hline Multi-User interference [100] & This occurs when, in MU-MIMO, multiple users try to transmit information simultaneously. & Considering that in 5G, performance and information forwarding improvements are sought, when switching to MU-MIMO, uncoordinated cells encounter more significant problems during user management. \\ \hline Adjacent Channel Interference & This occurs when the frequency channel of the device is overlapped. & If we do not have good bandpass filters, there will be interference from nearby frequencies. In 5G devices, this can have a significant impact. \\ \hline \hline \end{tabular}
\end{table} 
Table 8: _Cont._in neighboring cells attempt to use the same frequency simultaneously or when there is a simultaneous short-range transmission by two base stations in the same cell. This type of interference can severely damage 5G networks, particularly in architectures where there are micro- or macro-cells. Intra-channel and inter-channel interference occurs when there is little power within the macro network cell, though inter-channel interference can also occur due to the proximity of devices operating at different frequencies. Inter-Symbol interference occurs when one or more symbols interfere with other symbols, resulting in signal distortion due to phase or amplitude dispersion of the channel. Inter-Carrier interference occurs when the signal is lost due to an offset between the subcarriers, leading to large-scale or small-scale fading and variations in the received signal. Inter-Numerology interference occurs when using the numerology system for greater flexibility, leading to misalignments or imperfections known as inter-numerology interference.