Research On MU-MIMO Downlink Interference Suppression Schemes With Multi-Point Cooperation

With the services provided by mobile communication increasing fastly, wireless Internet and the demand for wireless data are rising rapidly.. However, a higher demand for transmission rate and communication quality are limited to the existing system power, bandwidth and complexity. Therefore, communication method with high spectral efficiency a has become a hot research field in wireless communication. Among them, the joint application of multiple input multiple output and cooperative transmission technologies make such studies be elevated to a new height.The severe co-channel interference come from serving cell and neighbor cells would seriously undermine the advantages of high spectral efficiency of multi-antenna technology and make communication systems become interference limited systems. It can eliminate interference between multiple users before signals be transimitted. Coordinated multi-point transmission is proposed mainly to solve the inter-cell interference problem. Precoding technology is an important means of suppressing co-channel interference within a cell. But the research program is not perfect, there are some serve problems to be solved:(1) research focus is too single and optimization objective is to enhance the overall system throughput or edge user throughput only, it can not accurately weigh the relationship between edge user throughput and quality of communication;(2) a large amount of data and signaling interaction are used for inter-cell interference suppression.A distributed precoding scheme, named block diagonalization with weighted signal to leakage plus noise ratio (BD-WSLNR) for MU-MIMO systems is proposed. It can nullify the intra-cell interference totally to ensure the overall throughput of the system and mitigate the weighted leakage interference to other cell users according to their interference affordability based on weighting factor calculated by channel quality information (CQI) to enhance edge users’ throughput. Besides, a generalized singular value decomposition (GSVD) based matrix calculation method is introduced to improve the calculation accuracy and reduce the gap between effective SINRs of multiple data streams. Simulation results show that, compared to the existed schemes the proposed precoding scheme achieves considerable gains in the spectral efficiency of edge users, while maintaining nearly the same achievable sum-rate. Besides, because the proposed algorithm requires only a small amount of interaction information between base stations to calculate weight factor, low implementation complexity is also a significant advantage.