Soft Frequency Reuse-based Interference Mitigation in Irregular Geometry Heterogeneous Networks

To counter the exponential data traffic growth, the fifth-generation (5G) communication system has significantly improved the system capacity and spectral efficiency. A heterogeneous network (HetNet) has been investigated recently as a potential evolved underlying network. In HetNet, the random deployment of small cells has overcome the hindrance of indoor coverage and capacity. However, at the cost of increased co-tier and cross-tier interference. Therefore, effective resource allocation (RA) algorithms are crucial to minimize mutual interference and achieve spectrum sharing in HetNets. A notable ICI mitigation strategy is the Soft Frequency Reuse (SFR) technique, however, in literature, SFR has been used mostly in perfect geometry networks such as Hexagonal geometry networks. Each cell in a realistic deployment seems to have a different ICI as well as an uneven cellular topology. In this work, a dynamic SFR scheme has been proposed for irregular geometry-based HetNet. To handle indoor coverage problems due to propagation path loss, Femtocells are deployed randomly in Macro base stations. SFR scheme is used for heterogeneous networks where cell structures are irregular and the partitioning of cells is based on the average threshold SINR value. Frequency Bands are allocated dynamically with a different number of users in the cell center and cell edge. To avoid cross-tier interference, the frequency bands are assigned in a manner that no same frequency bands are shared by Femto users and Macro users in the cell center and the cell edge. The proposed SFR scheme is analyzed and compared with the traditional SFR scheme. The obtained results show that Proposed SFR significantly improved the SINR and achievable throughput of both Macro and Femto users.