Time and Power Domain Interference Management for LTE Networks with Macro-Cells and HeNBs

Interference management for co-channel deployment of macro-cells and closed subscriber group (CSG) home-cells (HeNBs) are studied. We especially address the downlink macro-layer coverage-hole problem, where HeNBs may create too high interference to nearby macro-users, unless active interference management is applied. Interference management techniques based on HeNB power setting and partial Time Domain (TDM) muting of HeNBs are studied. Cases with TDM muting require optimization of the macro-cell packet scheduler, including taking into account that the interference level varies significantly at the users as function of the enforced muting pattern for the HeNBs. During subframes where HeNBs are muted, some interference is still generated due to the fact that signals like common reference signals are still to be transmitted. It is therefore studied how much the HeNB interference from muted subframes shall be reduced for TDM muting to perform better than schemes with simple HeNB power reduction.