The Research On Lattice-Based Interference Alignment In Wireless Communication

With the development of communication technology,interference in wireless systems and limited spectrum resources attract more attention.Traditional interference suppression or cancellation techniques reduce the spectral efficiency of individual users when the number of users increases,resulting in a decrease in overall system performance.Interference alignment technology proposed to deal with interference provides a new idea,which has aroused great interest of major research institutes and communication equipment manufacturers.This thesis focuses on a branch of interference alignment,namely,lattice-based interference alignment or signal-scale interference alignment,which is a powerful complement to signal space interference alignment and can effectively improve the data rate of static interference channel.This thesis firstly introduces the current research classification and performance index of interference alignment,studies the basic lattice theory and channel model required,and discusses the use of the lattice code in Gaussian channel and Deterministic channel.It paved the way for the design of interference alignment scheme and layered signals that meet the interference alignment constraints.Then,the lattice-based Compute-and-Forward strategy,which is suitable for interference alignment,is emphatically studied,and Integer-Forcing interference alignment with this strategy is proposed,which takes advantage of both signal space alignment and signal scale alignment,significantly improving system performance.Next,we analyze the mathematical principle and method of signal space and signal scale interference alignment.In particular,for the signal-scale interference alignment,the performance of lattice code and random code is compared,from the perspective of the sum rate,and then the lattice-based interference alignment scheme is designed through the analog signal space alignment scheme.The simulation results show that the lattice one has obvious advantages in improving the BER performance.Finally,this thesis explores the relationship between the dimension of lattice and BER in lattice interference alignment.Aiming at the problem that the performance of interference alignment using the lattice code is sensitive to the channel coefficients,a layered signal satisfying the interference alignment constraint for a constant Gaussian channel is designed according to the deterministic channel principle.The performance of the proposed form is finally evaluated with practical settings.By simulating,the signal form can improve the system Sum Rate.