Stochastic Geometry Analysis of Interference Coordination in NOMA-based Heterogeneous Networks

In this paper, we present a stochastic geometry-based analysis for the coverage probability of multi-tier heterogeneous networks employing interference coordination for non-orthogonal multiple access (NOMA). Two basic and conventional interference coordination alternatives; strict fractional frequency reuse (FFR) and soft frequency reuse (SFR) are analyzed, and their performance gains on different instances are illustrated. Coverage probability analysis has been extended to that of spectral efficiency for a fair performance evaluation between different FFR methods. The analysis covers both open-access networks with micro- and pico-cells, and closed-access networks with femto-cells. For heterogeneous networks, NOMA is observed to achieve better spectral efficiency than OFDMA, while OFDMA provides better coverage. Both analysis and numerical results reveal that strict FFR provides better coverage while SFR provides spectral efficiency advantage in open-access. However, strict FFR outperforms SFR for both measures in closed-access networks.