Alignment Chain-Based Closed-Form IA Solution for Multiple User MIMO Interference Networks

As a potential interference management technique, interference alignment (IA) can enormously improve the system capacity in the future mobile communication networks. However, the general closed-form IA solution in the multiple user scenario is still an open problem, which hinders the implementation due to the high complexity of iterative IA design. In this paper, a alignment chain-based closed-form IA solution scheme is proposed for generalized
$K (K > 3)$
-user multiple-input multiple-output (MIMO) interference channel. The alignment chains are sophisticatedly designed, on the basis of compressing the interference subspace and improving the degree of freedom (DoF) as much as possible. Then based on the alignment chains, the alignment chain equations are built, and the least-squares IA solution with optimal DoF or the exact IA solution with reduced DoF is provided, by using the theory of matrices. A series of simulation experiments are carried out to verify the proposed closed-form IA solution, and simulation results demonstrate its effectiveness and low computational complexity.