Cross-tier interference coordination of macro muting based on adaptive CQI hysteresis in HSPA heterogeneous network

Heterogeneous network (HetNet) has been studied earlier in the context of LTE. But lately, there are also some discussions about HetNet in HSPA. Cross-tier interference (CTI) is an annoying issue to be investigated in the co-channel HSPA HetNet (CHH) scenario. In this paper, we will focus on the downlink CTI problem in CHH and propose a solution to mitigate it. Our scheme involves the macro muting (MM) in which macro NodeB will mute itself at some certain sub-frames to reduce the CTI level in the system. We also enhance the MM scheme by introducing the adaptive CQI hysteresis (ACH) mechanism to avoid the issue that the low power node (LPN) in HetNet may use the improper CQI for transmitting when MM is implemented. Simulation results will show the benefits of our proposed scheme.