On Delay Compensation for HSPA+ HetNet Decoupling

Heterogeneous network (HetNet) where the macro cells are underlaid with low power node (LPN) has been introduced to HSPA+ to enhance the system performance in a cost-efficient way. But the Uplink and Downlink (UL-DL) mismatch issue caused by applying the heterogeneous deployment will inevitably limit the performance in both uplink and downlink HSPA+ system. To mitigate the UL-DL mismatch effect, E-DCH decoupling was proposed in HSPA+ HetNet recently, which has been discussed in 3GPP standardization process. However, some new problems driven from E-DCH decoupling have emerged, and one of the hugely important issues in this area comes to be known as the negative impact along with the reception delay of control channels for UL. In this paper, we will focus on this control channel delay issue in co-channel HSPA+ HetNet. The main contribution of this paper is to propose a novel adaptive grey prediction (AGP) using the recently historical data to make delay compensation. Furthermore, we develop a feasible implementation in practical HSPA+ HetNet to achieve our AGP method in practice. System-level simulation results will show the notable advantages of our proposed method.