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 macrocell BSs, compared to CWSIC based on hard replica.