Interference Analysis And Mitigation Method Studies Of LTE-A Heterogeneous Network

ABSTRACT:As the demand for larger capacity and higher quality of communication systems keeps growing, heterogeneous network which consisits of multiple relatively low power base nodes is becoming the major trend of LTE-A network topology due to its great superiority in improving the network overall capacity and solving the problems of hotspot and blindspot coverage. However, the introduction of these low power nodes has complicated the network structure of LTE-A networks, thus making the interference problems of such networks far more complicated and severe than any past communication systems. Therefore, a structured analysis of interference problems in LTE-A heterogeneous networks and the interference mitigation method are now becoming some of the key research directions in this area.Interfence mitigation methods such as interference coordination are the focused study areas since the release of3GPP R8. Among them, Interference Alignment (IA) is a newly rising hot research direction because of its achievability in the largest Degrees of Freedom (DoF) of the system. However, current studies of Interference Coordination and Interference Alignment in LTE-A heterogeneous networs are still rather limited. In this paper, we first briefly introduce the evolution direction and key techniques of LTE-A system. Later we conduct a classified analysis of different interference problems existing in LTE-A heterogeneous network, with emphasis on inter-cell cross-tier interference in both uplink and downlink of heterogeneous network and using a typical uplink interference scenario which is the interference between Macrocell users and Picocell eNBs as an example to conduct interference modeling studies and draw relative conclusions. On the basis of comprehensive summary of interfence problems of heterogeneous networks, this paper further introduce major current Inter-Cell Inteference Coordination (ICIC) method and the newly born Interference Alignment (IA) method. Afterwards, we analyze the drawbacks of traditional ICIC and IA methods and carry on improvement and optimization of current Power Control scheme and IA scheme under heterogeneous network environment with the purpose of lowering cross-tier inter-cell interference and enhancing the overall throughput of this system The Optimization of these interference mitigation schemes enable Power Control to automatically adjust the eNB’s transmit power according to the condition of its surrounding UEs, and Inteference Alignment to further benefit the performance at the receiving end. Simulation results show that the improved location-based power control scheme and the IA scheme including the information of useful channel matrix can further enhance the system’s performance.