Analysis of Interference Mitigation in Heterogeneous Cellular Networks using Soft Frequency Reuse and Load Balancing

Abstract

One of the promising solutions to meet the demands for ubiquitous coverage and high capacity in heterogeneous cellular networks (HCNets) is the co-deployment of small base stations (sBSs) inside the coverage region of a macro base station BS. Due to its high transmit power, most of the users get associated with BS. This results in imbalanced load distribution across the HCNets. To balance the load, users from BS are offloaded to low power sBSs to decrease the BS load and increase network capacity. However, BS now acts as a strong interferer for offloaded users. Therefore, a proactive interference mitigation technique together with load balancing is required to mitigate the interference and balance the network load. In this paper, we use the soft frequency reuse (SFR) scheme to abate such interference. Furthermore, we use cell range expansion (CRE) based cell association where coverage regions of sBSs are increased by using cell association bias to include more users. Moreover, we derive coverage probability expressions for the proposed model. Numerical results demonstrate that the SFR scheme together with association bias reduce interference and balance network load distribution.