Enhanced ABSF offsetting with virtual arbitrary blanking rate for time domain eICIC in LTE-Advanced

Almost-blank subframe (ABSF) is a time-domain technique proposed by the 3GPP to handle Inter-Cell Interference (ICI) in heterogeneous network environments (HetNet). In [1] we introduced ABSF offsetting as a novel scheme to reduce the blanking rate at the femto-cells operating in a HetNet comprised of macro-cells and femto-cells. This reduction in the blanking rate significantly improves the throughput of the femto-cell layer and comes with no expense on the macro-cell layer. In this paper we propose a modification to the original 3GPP ABSF proposal that allows a system to virtually achieve an arbitrary blanking rate via offsetting and proper resource partitioning. Moreover, we also propose various schemes for offset assignment namely simple round-robin, a load balancing scheme based on stretched bin packing, and a hard clustering scheme based on classical set theory. The virtual arbitrary blanking rate for resource partitioning and the offsetting techniques are evaluated through simulation. The results show that the virtual arbitrary blanking significantly improves the performance of the macro-cell layer in the scenarios where most of the users fall in victim state compared with the standard 3GPP ABSF proposal. This improvement comes with minimal effects on the throughput of the femto-cell layer; thanks to ABSF offsetting. The results also show that the balanced offsetting and clustering-based offsetting achieves a higher fairness index between the macro-cell UEs both normal and victim.