Virtual soft handoff enabled dominant interference cancellation for enhanced uplink performance in heterogeneous cellular networks

Heterogeneous cellular networks comprising overlays of macro-cells and small metro-cells are susceptible to excessive interference on the uplink because of the asymmetry between the uplink and downlink signal strengths. While soft handoffs can be used to mitigate this problem, existing methods applied in homogeneous macro-cellular deployments rely on more symmetric coverage in both directions and are not as beneficial in asymmetric coverage scenarios. In this paper, we propose a novel cooperative uplink reception scheme called “Virtual Soft Handoff (VSHO)” that enables cells suffering excessive interference to cancel out-of-cell interference or decode out-of-cell users in close proximity by canceling in-cell interference, leading to significant improvement in spectral efficiency and cell-edge throughput. As an important side benefit, virtual soft handoffs also enable users served by macro-cells to benefit from selection diversity, leading to further improvement in system performance.