Coverage and Rate Improvement Using Hybrid Reverse Frequency Allocation (RFA) Schemes in Three Region Non-Uniform HCN

The heterogeneous networks are deployed to enhance the coverage of cellular systems and to meet the increased demand of high-speed data. Small cells are underlaid in the existing macro-cell architecture and they share the licensed frequency spectrum with macro cells, which results in severe cross-tier interference for small cell users. Load balancing and interference mitigation in a multi-tier network is crucial to enhance network performance while efficiently utilizing the network resources. Reverse Frequency Allocation (RFA) is an efficient interference mitigation technique, which guarantees intercell orthogonality and interference reduction. In this paper, we propose three novel variants of RFA implemented in a 3 Region Non-uniform Heterogeneous Cellular Network (3R-NuHCN), to mitigate the impact of interference while balancing the network load. Simulation results show that the hybrid RFA schemes proposed in this paper outperform conventional frequency allocation in NuHCNs, especially in terms of downlink small cell coverage. The system performance is evaluated by analyzing several performance metrics such as network coverage, coverage per tier, and rate coverage.