Iterative multi-level soft frequency reuse with load balancing for heterogeneous LTE-A systems

This paper deals with the planning of two-layer Long Term Evolution-Advanced (LTE-A) cellular systems, taking both co-tier and cross-tier interference into account. In particular, we propose the novel Multi-level Soft Frequency Reuse (MSFR) scheme, where the users in three different regions of a macro/micro cell adopt distinct frequency segments and different transmission power levels. The optimization of power control parameters and cell association with MSFR results in a non-convex problem. We present the Iterative-MSFR (I-MSFR) scheme where the main optimization problem is divided into two sub-problems that can be subsequently solved by means of classical optimization methods. Finally, we propose two simplified schemes that achieve a comparable performance as I-MSFR in terms of utility, cell capacity, and outage conditions. I-MSFR and the simplified schemes have shown better performance than other schemes in the literature.