Joint User Association and Resource Partitioning with QoS Support for Heterogeneous Cellular Networks

In heterogeneous cellular networks (HCNs), it is desirable that users in macrocells should be offloaded to small cells with less congested traffic. However, these offloaded users often have lower signal-to-interference-plus-noise-ratio (SINR) than them in macrocells. The degradation of SINR can be partially alleviated by adopting interference avoidance techniques, such as resource partitioning, whereby the macrocell lets some fraction of such resources be unavailable. Naturally, an optimal offloading scheme should be tightly coupled with resource partitioning; the optimal partition in turn decides the number of offloaded users. Moreover, in order to reduce the call blocking probability of users, we need to consider their quality of service (QoS) requirements. Thus, in this paper, we propose a distributed QoS-aware strategy with joint offloading and resource partitioning for HCNs. We reveal that load balancing, by itself, is insufficient, and additional resource partitioning should be considered to reduce the call blocking probability. Meanwhile, we also show that compared with the best power association and range expansion association, the proposed scheme has more obvious superiorities over call blocking probability.