Research On Joint Power Allocation And Interference Alignment Algorithm In MIMO Interference Channel

With the popularization and widespread application of mobile communication,mobile terminals are the most convenient way to access to network resources in people's daily lives,which brings an enormous challenge to the capacity of the system limited by the frequency spectrum resources.Multiple input multiple output(MIMO)systems can greatly improve the system's frequency utilization without increasing the transmit power and system bandwidth.However,it results in the multiple access interference problem caused by spectrum sharing.Interference management technology in a technology called interference alignment,compared to the traditional interference management technology performance is better,become a hot area.In this thesis,the basic concepts of MIMO system and interference alignment technology,as well as the achievable schemes of IA in time,frequency and space domain are introduced.Then,four distributed interference alignment algorithms are studied,including Maximization SINR,Weighted Leakage Interference Minimization,Mean Square Error Minimization and Alternative Minimization.Afterwards,the K-user MIMO interference network is deeply studied.Since the classical interference alignment scheme ignores the channel environment experienced by the desired signal,the opportunity to achieve the further improved system capacity is lost.In order to solve this problem,a precoding matrix optimization method based on SVD decomposition is proposed in this thesis.Based on the SVD decomposition of the channel matrix and the chordal distance criterion of the matrix,the selected precoding matrix not only matches with the optimal characteristic sub-channels,but also leaves the desired signals away from the interference signal,which significantly improves the received signal strength and system capacity.Finally,Aiming to ignore the power allocation in the traditional interference alignment method,an improved water injection power algorithm for each data stream of each user at the sender is proposed in this thesis.Relying on the theory of alternating minimization,the proposed method can fully utilize the system resources in two aspects:(1)the interference alignment method is employed to eliminate interference;(2)the improved water injection power allocation algorithm is designed to boost the overall throughput.The simulation results show that the proposed algorithm improves the system throughput and reduces the total interference power by jointly optimizing the interference alignment and power allocation,compared with the alternate minimizing interference alignment algorithm in equal power allocation.