Interference Mitigation for Reconfigurable Intelligent Surface (RIS)-Aided Non-terrestrial Base Station (NTBS) in NOMA Downlink HetNets

Reconfigurable Intelligent Surface (RIS)-enhanced non-terrestrial base station (NTBS) is considered an advanced technology for enhancing the channel capacity of wireless communications. Inter-cluster and intra-cluster interference effects on NTBS-enhanced RIS are crucial considerations in wireless communication systems. Addressing these interference challenges is essential for maximizing the benefits of integrated technology, ensuring reliable and efficient communication in Heterogeneous Networks (HetNets). This research paper aims to mitigate interference while maximizing the total sum rate with non-orthogonal multiple access (NOMA) in downlink HetNets. Gray Wolf Optimization (GWO)-based meta-heuristic algorithm is used to optimize the reflection angles and coefficients of RIS. The suggested meta-heuristic algorithm that employs GWO is found to be capable of increasing the total sum rate significantly. Furthermore, the results show that incorporating RIS into multi-NTBS HetNets effectively boosts overall performance by improving the channel quality between NTBSs and their respective Ground Users (Gus) while reducing inter-NTBS interference. The findings of this work can act as a guide towards the mitigation of interference in Beyond Fifth Generation (B5G) networks.