Pre-encoded interference alignment algorithm in cognitive networks

Abstract

For a cognitive multi-input multiple-output (MIMO) network with a pair of primary users and multiple pairs of users, through the two-time pre-coding design of the cognitive user sender, the interference between the secondary users is reduced on the basis of eliminating the interference between the primary and secondary users, and the system capacity is effectively improved. The first pre-coding design uses the water injection method to align the cognitive user's interference with the primary user to the unused space sub-channel of the main user, and the second pre-coding design uses the maximum signal-to-noise ratio algorithm to eliminate interference between the secondary users. Theoretical analysis and simulation results show that while the algorithm effectively eliminates the interference to the main user, the throughput of the secondary user is significantly improved compared with the traditional water injection algorithm.