Spatial Interference Cancellation in Heterogeneous Networks with Biased Cell Association

Biased cell association has been widely applied in heterogeneous networks (HetNets) to offload users to small cells, which, however, results in degraded signal to interference plus noise (SINR) of these offloaded users. In this paper, we propose a spatial interference cancellation (SIC) scheme in HetNets with biased cell association, by which the interference from high-power base stations (BSs) to users located at the expanded region of lower-power cells is mitigated in the spatial domain. Using stochastic geometric tools, the analytical results are developed in terms of success probability for both the zero-forcing beamforming (ZFBF) scheme with full multiplexing and the proposed SIC scheme. Numerical results evaluate the impact of transmit antenna number and demonstrate the trade-offs between spatial multiplexing and interference mitigation. It is revealed that remarkable improvement of success probability is provided by the SIC scheme in fully loaded scenarios, while it is preferable to employ the SIC scheme to achieve higher network throughput in under loaded scenarios.