Investigation on Inter-Cell Interference Cancellation Scheme for Small-Cell User Equipments in Heterogeneous Networks Employing Cell Range Expansion

Recently, data traffic is explosively increasing in cellular mobile communication systems due to the prevalence of smart phones. A heterogeneous cellular network overlaid with small-cells to a macro-cell (HetNet), in which small-cell base stations (BSs) with a low transmission power are placed at the hot spot area of a macro-cell base station with a high transmission power, has been receiving attention in order to deal with the increasing traffic. For HetNet, Cell Range Expansion (CRE), in which a bias value is used for the reference signal received power (RSRP) from small-cell BSs, has been investigated as a promising approach to offload the traffic into the small-cell from the macro-cell. However, User Equipments (UEs), located in the small-cell area expanded by CRE, suffers large inter-cell interference (ICI) from the macro-cell BSs for the case of co- channel HetNet in which the same carrier frequency is used between macro-cells and small-cells. Hence, it is required for co-channel HetNet to mitigate ICI. In order to improve the downlink user throughput characteristics for co-channel HetNet employing large CRE bias value, this report investigates a successive interference cancellation (SIC) technique of codeword level SIC. The codeword level SIC (CWSIC) realizes a large ICI mitigation effect employing the output of the channel decoder for interference signals. Simulation results confirm that CWSIC based on soft replica effectively mitigate the ICI from the macro-cell BSs, compared to CWSIC based on hard replica.