Soft frequency reuse schemes for heterogeneous LTE systems

With the increasing demand of mobile data traffic, cellular networks are evolving towards heterogeneous systems involving cells of different sizes (e.g., pico, micro, and macro cells). The presence of small cells is causing new interference issues that require the introduction of frequency reuse techniques suitable to manage both co-tier and cross-tier interference. In this paper, we propose a novel Soft Frequency Reuse (SFR) scheme for LTE-A, based on three frequency segments (named Three-Band Improved SFR, 3B-ISFR) where the Frequency Reuse Pattern (FRP) allocation scheme for micro cells is centralized at the level of each macro cell. This scheme is based on the exchange of measurements made by the micro cells with their macro cell (cognitive-assisted approach) and includes an intra-cell offloading algorithm to balance the load between cell-center and cell-edge of each micro/macro cell. The goodness of 3B-ISFR has been proved by means of performance comparisons with other schemes in the literature in terms of outage probability and average cell capacity.