# Interference Mitigation Strategies in Beyond 5G Wireless Systems: A Review
## 3 Classification and Evolution of Interference Management Strategies in B5G Networks
### Classification and Analysis of Interference Management Strategies in B5G Networks
#### 3.2.2 Heterogeneous Networks  
B5G and future wireless networks are expected to offer services with high quality, very low energy consumption, much-improved security, ultralow latency, ultrahigh data-rate, and massive connectivity [95; 96]. Compared with the legacy systems, B5G and future communication systems will be not only more advanced but also more complex [60]. The integration of HetNets is considered one of the main solutions for achieving the objectives of B5G networking systems [97; 98]. HetNet is a network densification technique to accommodate ever-increasing traffic in a limited geographical region where a large number of transmission nodes are installed [99]. The use of HetNets makes it possible to reuse the spectrum in space [100], which, on the other hand, results in higher interference scenarios [101]. As shown in Figure 5, the B5G heterogeneous cellular architecture involves overlapping layers of macro, micro, and SCs, creating complex interference patterns. Understanding this layout is critical for developing effective IMI techniques across tiers [1]. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Issue** & **Methodologies** & **Advantages** & **Limitations/Future Works** & **Ref.** \\ \hline Optimize the transmission power of D2D links, mitigate the interference generated by D2D communication to the mm-Wave SC, and fully utilize the BW of the mm-Wave spectrum. & IM strategy based on a Stackelberg game utilizing the mm-Wave SC network. & Maximizing the total throughput of the proposed system by keeping the SINR as high as possible. & The UL transmission was not considered in this study. \\ \hline Minimize the effect of the mm-Wave SC network. & The two-phase combinatorial technique is proposed to determine a RA, taking into account the constraint of the total data rate. & Maximizing the total data rate of the proposed system. & The non-uniform interference will be considered. & [85] \\ \hline Minimize the effect of the mm-Wave SC network. & The two-phase combinatorial technique is proposed to determine a RA, taking into account the constraint of the total data rate. & Maximizing the total data rate of the proposed system. & The non-uniform interference will be considered. & [85] \\ \hline To control the interference between D2D users and cellular users. & Maximum RSS-based MOS strategy. & Improving the area’s SE of the proposed scenario. & The DOL scenario was not considered. & [86] \\ \hline Maximize the data rate transmission and minimize the effect of interference with other levels while preserving the minimum QoS required. & A novel IM technique based on graph theory that concurrently addresses power adaptation, link selection, and MOS to maximize the number of communication links while minimizing power consumption. & Maximizing the EE and effectiveness of the proposed scheme. & The UL scenario was not taken into consideration. & [87] \\ \hline To mitigate the effect of interference that affects the proposed scenario. & A novel MOS strategy for D2D-enabled HetNets. & Improving network reliability compared to traditional approaches. & The throughput and reliability of D2D link will be considered. & [88] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._Minimizing the cell sizes in HetNet requires a wide variety of spectrum solutions and higher SE at each BS to satisfy future wireless network requirements for improved coverage, lower latency, and higher data rates [102]. In addition to the advanced modulation and coding [103], m-MIMO antenna techniques [104], and additional spectrum, raising the number of cells represents the most critical parameter to meet the increasing traffic demand [105]. Homogeneous cellular systems, however, face limitations when increasing the number of cells, such as increased BS cost and site acquisition problems in urban areas. HetNets can be seen as a more versatile and cost-effective approach to such constraints [106].