On adaptive range expansion for UL-DL imbalance mitigation in HSPA HetNet

Heterogeneous network (HetNet) which contains different transmission power NodeBs, has been discussed earlier in LTE system. But recently, HetNet is currently being standardized for HSPA system by 3GPP working group. In co-channel HSPA HetNet (CHH), Uplink-Downlink (UL-DL) imbalance caused by the hugely different power from different types of transmission nodes is a key problem leading to many undesirable conditions such as unbalanced load and severe interference. The main contribution of this paper is to propose an adaptive range expansion (ARE) mechanism to mitigate the UL-DL imbalance in uplink CHH (UCHH). Our scheme tries to adaptively calibrate the parameter of range expansion (RE) by means of introducing a "Equivalent User Equipment (UE)" and using it as a reference to reflect the uplink reception quality of other UEs. Simulation results will show the advantage of our proposed scheme.