Research On Power Control In Two-Tier Femtocell Networks And Simulation Implementation

In the era of mobile Internet, the demand for wireless data traffic is strikingly expanding and according to the Cisco VNI the global mobile data traffic has been forecasted to reach 292EB in 2019 compared with 30EB in 2014, almost ten-fold increase. Meanwhile, surveys show that approximately 50% of the voice traffic and 70% of the data traffic occur indoor, and 30% of business users and 45% of home users experience poor indoor coverage problem. The OFDMA-based Femtocell network, which is assumed a good solution to improve indoor coverage and system capacity, is a research hotspot that gains extensive attention.After introducing Femtocells, the new network is comprised of two separated layers:the Macrocell layer and the Femtocell layer, and the network architecture becomes complicated and flexible, namely two-tier Femtocell network. Also, the consequent interference, including the inter-layer interference and cross-layer interference, gets more severe, making interference management techniques crucial. Power control is the key technology for two-tier Femtocell network, which can effectively reduce the interference and improve the quality of service for users. This research work is mainly focused on the power control technique in two-tier Femtocell network with the LTE-A system. The main contents are summarized as follows:(1)The related theories and technologies of two-tier Femtocell network are summarized. First, the network architecture and key techniques of the LTE-A system are described. Then, several existing indoor coverage technologies are compared and analyzed. Finally, the research state of Femtocell network, especially the interference management technique, is summarized, pointing out the research problems of the power control.(2)The system simulation methodology is briefly introduced. In line with 3GPP standards and proposals on Femtocell, the system level simulation platform for two-tier network is implemented, including functional requirements of modules and detailed design and implementation procedure. Also, verification and analysis of the power control algorithm in power control module of the platform is presented.(3)The power control algorithm based on potential game theory is proposed to deal with the interference in two-tier Femtocell network. Firstly, the non-cooperative game in economics is introduced. Then, the existence and uniqueness of Nash equilibrium point are proved, using properties of the potential game. Afterwards, the optimization problem is solved by choosing the proper decision-making criterion and iteration timing. Simulation results show that the proposed PGPC algorithm can effectively improve the outage probability and average throughput performance of Macrocell users with little influence on Femtocell users, balancing the performance of both.