A Novel m-th Best User Association Scheme for Multi-Tier Heterogeneous Networks

Due to resource constrain and load balancing problems in heterogeneous networks (HetNets), traditional best user association (UA) scheme might be unavailable. To this end, this paper focuses on the non-best UA scheme for K-tier HetNets, and proposes a novel m??-th best average biased received power (ABRP) UA scheme, of which a user is associated with the base station (BS) having the m-th strongest ABRP. For the proposed m-th ABRP UA scheme, modeling the positions of network elements in each tier as a homogeneous Poisson point process (PPP), and using stochastic geometry and order statistics, we perform the analysis of the probability that a typical user is associated with a BS that has the m-th strongest ABRP as well as the corresponding statistical description. Our mathematical analysis and numerical results show that for a given tier k, when the transmission power or density of BSs of the tier k is small relatively, the UA probability (m>1) increases with or . However, when the power or density of BS is large, the UA probability decreases. The proposed scheme can guide for the design of HetNets.