Small cells are becoming essential to offer a promising solution for dramatic mobile traffic growth in future mobile networks. Especially, massive enterprise femtocells are expected to provide high capacity to fulfill high data demands in buildings in order to offload indoor traffic from outdoor macro cells in that over 80% of mobile data traffic is generated indoors. However, as one of the major challenges, inter-femtocell interference gets worse in 3D in-building scenarios because of the presence of numerous interfering sources and needs to be considered in the early network planning phase. The indoor network planning and optimization tool, iBuildNet®, makes accurate prediction of indoor wireless RF signal propagation possible to guide actual indoor femtocell deployments. In this paper, a semi-static resource allocation scheme based on fractional frequency reuse (FFR) is developed to avoid interference on cell edge users for dense indoor femtocell deployments. The minimum number of subbands used in the scenario is worked out with a node-coloring heuristic algorithm. Extensive simulations in a multi-floor building are performed over iBuildNet® to evaluate the performances of the developed scheme. The simulation results illustrate that the developed scheme outperform the traditional FFR-3 scheme that is popular in macro-cell networks, in terms of cell edge user data rate and average user data rate.
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