Virtual Soft-Handoff with Resource Blanking in Heterogeneous Networks
10 June 2014
Heterogeneous Networks (HetNets) comprising overlays of macro-cells and small-cells provide an effective solution to address the ever-increasing capacity demand in mobile networks. However, in co-channel deployments where small cells are placed within the coverage area of high-power macros and operate in the same frequency band, excessive interference between macro and small cell transmissions may limit potential system capacity and cell edge (i.e., 5th percentile user) performance. For the downlink, partial blanking of macro-cell transmissions has been proposed to mitigate interference but this does not address the uplink interference problem and also leads to under-utilization of the uplink as an undesirable byproduct. In this paper, we address this problem by proposing a class of low-complexity, cooperative interference mitigation schemes referred to as Virtual Soft-Handoff techniques which exploit uplink/downlink asymmetry in selecting the best uplink reception point for each user while mitigating interference. Studies of these techniques show substantial gains (up to 100% in cell-edge throughput) compared to a 3GPP LTE based HetNet while still achieving modest improvements of around 10% in average throughput.
