Downlink interference mitigation for two-tier LTE femtocell networks

Femtocells are low-power, very small-service-area (e.g. home or office environment) cellular base stations that will significantly impact the cellular landscape in the next several years. One of the most important open technical issues related to femtocells concerns the impact of femtocells on the performance of the conventional macro-cell system and the whole two-tier system, in this paper, a study of LTE wireless mobile system is proposed; First System Performance is modelled and simulated for the effect of insertion of closed subscriber group femto Access Points (FAPs) into the network and how it affects the overall performance of the systems. Then a study of the effect on the macro-cell neighboring users for the cases of the LTE system with random resources assignment, and the case of a new resources assignment procedure proposed for the closed subscriber group FAPs based on the Fractional Frequency Reuse (FFR) of the macro base stations. The performance of the model is evaluated throughout system level simulations and it is shown that insertion of FAPs has some benefits and some drawbacks on the network, and it is also shown that the using of the proposed assignment procedure overcomes some of these drawbacks.