A survey on modeling interference and blockage in urban heterogeneous cellular networks

In this paper, we provide a survey on abstraction models for evaluating aggregate interference statistics in urban heterogeneous cellular networks. The two principal interference shaping factors are the path loss attenuation and the interference geometry. For both factors, our survey systematically summarizes state-of-the-art models and outlines their strengths and weaknesses. In the context of path loss attenuation, we give an overview on the basic propagation mechanisms and the various approaches for their abstraction. We specifically elaborate on random shape theory and its application for representing blockages in indoor and outdoor scenarios. In terms of interference geometry, we present techniques from stochastic geometry as well as deterministic approaches, outlining their evolution and limitations. Throughout the paper, challenges under discussion are scenarios with both indoor and outdoor environments, distance-dependent shadowing due to blockages, and correlations among node and blockage locations as well as the distinction between cell center and cell edge. Our goal is to raise awareness on not only the validity and tractability but also the limitations of state-of-the-art techniques. The presented models were chosen with regard to their adaptability for a broad range of scenarios. They are therefore expected to be adopted for describing the fifth generation of mobile networks (5G).