Inter-Cell Interference Coordination

IMT-Advanced (International Mobile Telecommunications-Advanced) next generation mobile communication technology has proposed higher standards and requirements for spectral efficiency, cell edge data rate and peak rate. Because next generation mobile system employs OFDM (Orthogonal Frequency Division Multiplexing) multiple access technology, inter-cell interference becomes key issues of constraining system network. Thus Inter-cell interference coordination technology becomes the focus of current research. The existing interference suppression techniques include interference coordination, interference cancellation and interference randomization techniques. Because interference coordination is flexible and low implementation complexity, interference coordination has been adopted by LTE (Long Term Evolution) system and turns into the mainstream technology of interference suppression.In this thesis, the existing interference coordination scheme is studied and analyzed firstly. On the basis of existing static soft frequency reuse interference coordination scheme, the cell edge frequency band is further subdivided into master band, priority band and borrowed band. And the priority band of this cell and the borrowed band of adjacent cell is duplicated. Then through studying HII/OI (High Interference Indicator/Overload Indicator) interactive information and according to the idea of coarse-grained and average value, the trigger mechanism of HII/OI interactive information is designed. Through the HII/OI interactive information of inter-cell, each edge frequency bands (priority band/borrowed band) are dynamic adjustment. In case for some fixed edge frequency band (master band) serving this cell, there is a flexible edge frequency band (priority band/borrowed band).A dynamic soft frequency reuse inter-cell interference coordination scheme based on HII/OI is proposed.Based on this scheme, an optimization scheme is also proposed. Power control and user satisfaction are considered. The optimization scheme is based on HII/OI and power control. Based on these two schemes, system-level simulation is conducted to validate the performance of interference coordination.According to the Group Cell architecture and channel reciprocity of TDD(Time Division Duplex) system, downlink power allocation is based on the SNR value of the uplink channel. A simplify interference coordination scheme based on the Group Cell architecture is proposed. And field experiments are used to verify the performance of interference coordination.System-level simulation assessment results show that theses two schemes can ensure that the capacity of the cell center is unchanged and cell edge user performance is greatly improved. Because each cell frequency band resources are fully utilized, enhancing overall system performance can be realized. Then the test results of interference coordination scheme based on the Group Cell architecture show that the coverage of base station can be expanded into two cells. According to the allocation algorithm for downlink power of the scheme and in the case of total power unchanged, the performance of the edge portions of the two cells which are not adjacent is not affected and the performance of the edge portions of the two cells which are adjacent is enhanced. Thus the goal of suppressing inter-cell interference is achieved.Finally, this thesis is summarized, the shortcomings of this thesis are analyzed and follow-up study is discussed.