Techniques for Interference Mitigation Using Cooperative Resource Partitioning in Multitier LTE HetNets

Abstract

Almost blank subframes (ABSs) have been proposed in the literature as a means to provide interference-free resources to mobile users. The use of ABS becomes inevitable in LTE heterogeneous cellular networks because of severe interference to small cells. Picocell edge users are typically the victims because of high interference exposure from macrocell tier. In case of hotspots with high-user density, picocells cannot provide coverage to the entire hotspot, thus forming a dense ring of macrocell users around picocells. These macrocell users are highly affected by picocell tier and hence should also be considered as victim users (VUEs). We propose that to protect these macrocell VUEs, macrocells and picocells should operate in a cooperative manner, such that not only macrocells should use ABS, but picocells should also use ABS to provide interference-free resources. We also introduce the concept of universal blanking pattern to coordinate among various base stations. We propose two methods for joint ABS density calculation for macrocells and picocells—bitrate utility-based optimization and physical resource block (PRB) allocation ratio-based formulation. Users with different bitrate demands are considered generating more realistic simulation scenarios. Exhaustive simulations illustrate that the proposed schemes offer significant improvement in VUE throughput as well as overall system throughput.