Enriched K-Tier HetNet Model to Enable the Analysis of User-Centric Small Cell Deployments

摘要

One of the principal underlying assumptions of current approaches to theanalysis of heterogeneous cellular networks (HetNets) with random spatialmodels is the uniform distribution of users independent of the base station(BS) locations. This assumption is not quite accurate, especially foruser-centric capacity-driven small cell deployments where low-power BSs aredeployed in the areas of high user density, thus inducing a natural correlationin the BS and user locations. In order to capture this correlation, we enrichthe existing K-tier Poisson Point Process (PPP) HetNet model by consideringuser locations as Poisson Cluster Process (PCP) with the BSs at the clustercenters. In particular, we provide the formal analysis of the downlink coverageprobability in terms of a general density functions describing the locations ofusers around the BSs. The derived results are specialized for two cases ofinterest: (i) Thomas cluster process, where the locations of the users aroundBSs are Gaussian distributed, and (ii) Mat\'ern cluster process, where theusers are uniformly distributed inside a disc of a given radius. Tightclosed-form bounds for the coverage probability in these two cases are alsoderived. Our results demonstrate that the coverage probability decreases as thesize of user clusters around BSs increases, ultimately collapsing to the resultobtained under the assumption of PPP distribution of users independent of theBS locations when the cluster size goes to infinity. Using these results, wealso handle mixed user distributions consisting of two types of users: (i)uniformly distributed, and (ii) clustered around certain tiers.