# 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
[PERSON] and [PERSON] [116] proposed a cross-tier UL interference synchronization algorithm for two-tier networks to reduce the interference signals of the macro-cell consumer at the receivers of femto-cells. The results showed that the proposed algorithm surpasses other IA algorithms as it greatly improves the potential of the signal to interference ratio (SIR) and the capacity of the system. A new algorithm that selects the most suitable IoT terminal pair and provides eNodeB with perfect signals to supply relay-assisted communication for IoT terminals is presented in [117]. It was found that the suggested algorithm increases the overall network throughput and the amount of simultaneously served information technologies. [PERSON] et al. [118] investigated UL coverage in the existence of ICI and jammer interference in multi-tier HetNets. The authors found that due to improved ICI and jammer interference reduction, the reverse frequency allocation (RFA) results in higher UL coverage compared to the no-RFA scenario. [PERSON] et al. [119] presented a study on the security analysis of the suggested IM mechanism with beam forming, spectral reuse (SRE), and D2D communications for the DOL in a two-tier HetNet. The IM mechanism was found to enhance the user's secrecy rate with the use of some SRE interference D2D communications interference, and beam forming technique. A technique of hybrid IM depending on dynamic enhanced inter-cell interference coordination (eICIC) and CoMP transition is proposed in [120]. It was found that the suggested scheme can attain the best SE both at macro-cell and hypothetical cell edges. In [121], the authors proposed a novel joint BS UE organization and POC systems for HetNets. They found that the proposed system showed the advantage of innovative algorithms in both traffic off-loading and IM. Two energy-efficient power management and RA algorithms which are the EE fairness algorithm, and the global EE optimization algorithm are suggested by [PERSON] and [PERSON] [122]. The results showed that the algorithms are efficient in reducing interference but to a different degree. [PERSON] et al. [123] developed a RA scheme depending on matching theory to minimize reciprocal interferences between D2D and cellular communications. They reported that the proposed scheme is capable of realizing attractive network achievement with much less cost and complexity. [PERSON] et al. [124] applied two universal filtered multi-carrier (UFMC)-based interference elimination schemes for the SC HetNet, where both the ICI and the intra-cell interference occur. The authors concluded that the suggested UFMC-based schemes can effectively reduce the interference and mitigate the impact of frequency offsets. An interference reduction system was investigated by [PERSON] et al. [125]. This study concluded that the suggested system attains a large enhancement in SE as compared with conventional systems. The summary of previous studies of HetNets is presented in Table 3.