The LTE macrocells with the architecture of Fractional Frequency Reuse and Cognitive Radio OFDMA based Femtocells

Recently, Studies show that to date the demand for mobile high data rate occurs mainly in buildings. Moreover based on these studies sixty percentages of voice calls and ninety percentages of data traffic originate indoors. So indoor coverage which is associated with high quality services and high data rate that do not use extra radio resources is even more critical. femtocell technology is presented to cope with these challenges. One of the most important technical challenges faced by the femtocells is interference management. To cope with it many solutions have been presented by different researches. Fractional frequency reuse (FFR) is a solution in order to mitigate the inter-cell interference especially for the cell edge users. Furthermore it improves the total capacity of the network. In this paper we combine the LTE macrocells with the architecture of FFR and cognitive radio OFDMA based femtocells. And we choose Underlay approaches for secondary spectrum allocation. In our proposed scheme femto-macro and macro-macro interference are considered. Further for power control and capacity improvement, water-filling algorithm is taken into consideration. The simulation results show that the proposed scheme enhances the overall network throughput.