Research On MIMO Interference Coordination In LTE-Advanced System

As 3GPP (3rd Generation Partnership Project) has the LTE (Long term evolution) release 8 frozen, the wordwide commercial use of LTE will be presently. At the same time ITU is now collecting candidate techniques for IMT-Advanced. OFDM and MIMO are the basic elements of LTE. High performance and low complexity application of advanced techniques based on these two elements is challenging. So LTE and LTE Advanced is the research hotspot.Firstly, in chapter two this thesis give a brief introduction about the key techniques of LTE and LTE-Advanced. Then describe the implementation of FDD-LTE system simulation platform including the structure of the platform, key modules and the ability to support multi-cell coordination. According to 3GPP reference, the platform was calibrated. After that, in charpter three, signal and interference model of multi antenna system are analysed. And then some available theories in this area are summaried and some interference coordination schemes used in LTE and discussed in LTE-Advanced are presented.Secondly, in chapter four LTE transmission mode 4 (close loop precoding) is researched from several aspects, including the interference should be modeled differently when using precoding, different feedback granularity and feedback mode 3-1 defined by LTE protocol. When feedback mode 3-1 used for transmission mode 4, outer loop link adaptation is used to improve the performance.Finally, in chapter five several multi-cell MIMO interference alignment schemes are summarized. Multi-cell codebook based precoder coordination is implemented on the platform. Two schemes including precoder restriction and interference avoidance are studied. A precoder selection scheme according to the null space of interference matrix is proposed, with a proposed selective interference avoidance method, the proposed sheme will improve the cell edge user throughput. From the comparison of these schemes, this thesis concludes that the coordination degree is the key parameter to balance performance gain and loss.