Efficient coverage management of pico cells in HetNets via spectrum slicing, cell biasing, and transmit power spreading

Cell biasing is an effective solution for mobile user offloading in Heterogeneous Cellular Network (HetNet). Cell biasing modifies the user association criteria by incorporating Range Expansion Bias (REB) in traditional reference signal based user association technique. For sparse user distribution, REB for picocells does not offload users located outside RSRP Threshold Coverage Area. This is because the actual Reference Signal Received Power (RSRP) value for such users is lesser than the threshold RSRP value for successful communication. On the other hand, using a negative REB value for dense user distribution around picocells is not desirable because it leads to higher interference at users and high energy consumption at macrocells. In this paper, we suggest a unified framework for coverage optimization using spectrum slicing and transmit power spreading. Our proposed framework considers a combination of subchannel transmit power and REB which is based on the user distribution around picocells. Additionally, in order to protect the signal quality of macrocell users located close to picocells, we suggest location aware subchannel allocation technique. This technique maximizes the number of Interference Free subchannels for macrocell users. Obtained results show that our proposed framework can significantly improve the coverage and system blocking for HetNet.