Precoder Design Of Base Station Based On Interference Alignment

The lack of frequency spectrum and the demand for higher data rates have become almostcontradictory issues in today’s wireless communication field. To solve the problems, multi-antennatechnology which can achieve higher spectralefficiency will be widely used in next generationwireless communication systems. However, interference is inevitable in multi-cell multi-antennasystems, especially in multi-users MIMO interference channel, co-channel interference has becomethe primary factor of restricting the system capacity. If there is no effective interferencemanagement strategies, the high spectrum efficiency derived from multi-antenna technology willcease to exist. When using conventional interference management approaches, the spectrumefficiency of each user decreases as the user number increases, and the sum-capacity is interferencelimited. Interference alignment is a novel interference management approach using the idea ofoverlapping interference space. Research shows that the sum-capacity increases proportionally withuser number when using interference alignment. Interference Alignment technology was put forthto become a research hotpot in wireless communicationsThis thesis firstly analyzes the different communication channels, and discusses the weaknessof classical minimum interference leakage algorithms at high SNR in the interference channelmodel. Based on the above analysis we put forward the idea of secondary alignment. The secondaryalignment is achieved by rotation vector in this paper. That means interference matrix is restrictedto ‘common’ by the rotation of vectors. The simulation results show that this idea can indeedenhance the performance of system capacity.This thesis also makes a brief analysis for the current status quo that most of precodingalgorithms fail to achieve the maximum SINR while preserving the dimensionality of the desiredsignal, and presents a maximum virtual SINR distributed iterative algorithm. Based on these, weextend the algorithm to the case of multi-streams, and by means of mathematical methods we obtainthe maximum SINR at receiver while preserving the dimensionality of the desired signal.Simulation results show that the algorithm can enhance the system capacity.