Performance Evaluation Of Interference Suppression Techniques In LTE-A Heterogeneous Networks

In order to meet the demand of explosive growth of wireless communication data rate and higher quality of network coverage, the traditional network architecture has been unable to meet the requirements because of its own limitations. A new wireless network architecture has emerged as an inevitable trend. In this situation, 3GPP proposed heterogeneous networks in the standardization process of LTE-A. In heterogeneous networks, cell spectrum efficiency and transmission date rate are effectively improved, while facing a challenge of inter-cell interference suppression. To mitigate the interference, the thesis conducuted computer simulations for interference cancellation evaluation in different heterogeneous network scenarios and proposed several inter-cell interference coordination (ICIC) techniques of uplink and downlink.Firstly, the thesis introduces the development of mobile communication networks. The background and interference problems of LTE-A heterogeneous networks are described in detail. We focus on the existing uplink and downlink ICIC techniques and summarize the pros and cons of different ICIC techniques.The third chapter proposes improved ICIC techniques to mitigate the interference in different scenarios of heterogeneous networks. For uplink heterogeneous networks, we propose two ICIC schemes:a user-specific joint power control and resource allocation scheme and a dynamic user-specific power control scheme. Sim-ulation results verified that average user rates and edge user rates are significantly improved by the proposed schemes. In downlink dense small cell networks (SCN), a dynamic grouping based ICIC scheme is proposed. Simulation results show that the improvement of system performance becoms more pronounced when there are more small cells in the network.The fourth chapter constructs a downlink system-level simulator in LTE-A heterogeneous networks based on 3GPP TR 36.872. The paper elaborates the design and implementation of each functional mod-ule of the simulator. We introduce the design process of the main loop and provide the design flow of the feedback receiving module. We also add a graphic user interface (GUI) for the simulator in order to facilitate the parameter setting under different scenarios. In addition, the paper provides several simulation outputs, including directional antenna gain of macrocell sector, performance comparison of macrocell UEs and small cell UEs.Finally in chapter five, we compare the system performance of scenario 1 and scenario 2a by our con-ducted system-level simulator. The performance of different small cell transmission power in the downlink and different CRE biases are also compared by the simulator. In addition, the paper studies the frequency reuse schemes based on the system-level simulator. Key parameters of the frequency reuse schemes, includ-ing SFNR threshold, spectrum ratio and downlin power ratio, are tested for comparison in the simulator as well. Simulation results show that the performance gain of the frequency reuse schemes is about 5%～10% in scenario 1 when the user load is not heavy.