Research On The Interference Alignment In MIMO System

By designing the precoding matrix and the receiving filter matrix separately at the transmitter and receiver,the interference alignment technique can completely eliminate the same frequency interference caused by the user.Besides,it can also increase the reachability degrees of freedom of the system while improving the system space division multiplexing gain.Interference alignment technology requires the transmitter to obtain accurate CSI,while the blind interference alignment technology can eliminate the CSI in the case of the lack of interference.By symbolizing the source signal of the transmitter,the blind interference alignment technique can interfere with the interference subspace in a particular time slot,thereby eliminating interference.At present,interference alignment technology and blind interference alignment technology are not practical;there are many problems to be resolved;for example,the capacity enhancement of the interference alignment technology,and the limitations of the application scene of the blind interference alignment technology and so on.Based on these problems,this paper does the following research on the interference alignment technology and blind interference alignment technology respectively:Firstly,this paper studies the evolution of interference alignment technology and blind interference alignment technology respectively,and analyzes several recent latest technologies,such as ARA algorithm and n BIA algorithm.Through the analysis,we found that,for the interference alignment technology,although the system's degree of freedom is high,but the system's capacity has changed little.For the blind interference alignment technology,the existing algorithms are mostly for single-cell MIMO channel and K User MIMO channel and so on,but less of the research for the multi-cell multi-user MIMO system scene.Then,aiming at the problem that the system capacity is limited in the existing jamming alignment technology,this paper proposes an improved algorithm--ISC algorithm for interference alignment technology in multi-cell multi-user MIMO system.Based on the actual communication status of each cell,the ISC algorithm divides the users in each cell into aligned users and misaligned users.Based on the number of unaligned users in each cell,the ISC algorithm can flexibly adjust the number of antenna requirements on both sides of the base station and the user,thus reducing the amount of antenna resources at both ends of the transceiver.By simulation,we find that the number of antennas required by ISC algorithm is less than that of existing algorithms,and the ISC algorithm has the highest capacity when the system antenna configuration is the same.Finally,aiming at the limitation of the application scene in the existing blind interference alignment technique,this paper proposes an improved algorithm-m BIA algorithm,which is suitable for the blind interference alignment technique of two-user MIMO system scene.The m BIA algorithm eliminates the ICI of the user by generating a precoding matrix at the base station.Then,according to the preset super symbol and the heterogeneous channel model,the m BIA algorithm can align the IUI of the user to the number of interfering subspaces of the user,and then decode the user's desired signal.Through the simulation,we find that the average Do F of the m BIA algorithm is the highest and the bit error rate is the lowest.