An Overview of On-Demand Deployment Optimization of Small Cells

On-demand deployment (OdD) of Small Cells (SC) achieves dynamic response to varying environment, offering high Quality of Service (QoS), supporting the promise of 5G with anticipated proliferation of the traffic size and the support of unprecedented huge number of devices. However, the densification using SCs, along with their required complex dynamic infrastructure, leads to complicated formulation and diverse optimization modeling. The high modeling diversity for different OdD applications (e.g., residential and industrial environment) results in difficulty in the optimization modeling and solving for SC OdD. In this article, we present a generic SC overlaid HetNet infrastructure, for various OdD applications. We conduct a survey of existing works, analyzing the modeling, solving and analysis of OdD optimization, categorizing according to the optimization objectives. Finally, we highlight the challenges in existing solutions; and hence, deduce a list of future research opportunities in the area of OdD optimization in SC-based mobile networks.