Uplink Inter-Site Carrier Aggregation between Macro and Small Cells in Heterogeneous Networks

With uplink inter-site carrier aggregation (CA), it is possible to configure a user equipment (UE) to transmit on multiple layers (macro and small cells) simultaneously, each of which may exhibit different radio channel characteristics. This introduces new challenging issues such as how to configure the UEs with CA and how to assign UEs on different layers. In this paper, we propose an uplink inter-site CA configuration algorithm by taking some of the key factors into considerations (i.e., cell load conditions, UE transmission power constraint, and potential interference to other cells) when deciding whether UEs should be configured with uplink inter-site CA or not. Simulation results show that with proper configuration of UEs to operate with uplink inter-site CA, good user throughput gain compared to the case without inter-site CA can be achieved at low load due to larger bandwidth accessibility, but the CA gain decreases as the load increases.