Min–Max User-Pair Association Criterion and Outage Performance of K-Tier Relay-Based Heterogeneous Networks

This paper focuses on the user-pair association for multi-tier relay-based dual-hop heterogeneous networks (HetNets) and proposes a novel min–max user-pair association (MM-UPA) criterion by integrating the bias factors, which is an evolution of conventional single-hop user association based on receive signal strength (RSS). The core idea of the proposed MM-UPA is that, in each tier the nearest relay to a typical user-pair is characterized by the maximum of the RSS reciprocals \({1 / {P_{SR}^{j} }}\) and \({1/ {P_{RD}^{j} }}\) by the source and destination from relay. Then, a typical user-pair is associated to the relay based on minimizing these maximums of each tier. This proposed MM-UPA criterion is fit especially for the relay-based HetNets due to effectively exploiting the source-relay and relay-destination links simultaneously. With the MM-UPA criterion, by using stochastic geometry and homogeneous Poisson point processes, we present the analytical expression of the probability that a typical user-pair is associated with a relay of the kth tier as well as the corresponding statistical description of the distances from the source and destination of a typical user-pair to its associated relay. Finally, the average outage probability of a typical user-pair relay communication link is derived. The presented simulations and numerical results validate the derivations.