Uplink multi-user MIMO interference cancellation algorithm for LTE-A systems

An uplink multi-user multi-input multi-output (MIMO) multiple access interference cancellation algorithm is proposed for Long Term Evolution-Advanced (LTE-A) system. The base station (BS) obtains the null space of pairing user´s channel matrix by channel state information, and then this null space is constructed as the transformation matrix which maintains the multiplexing degree of spatial channel. The received signal at the BS is processed by the transformation matrix, and the multiple access interference of pairing user can be eliminated. Furthermore, during the resource scheduling, the user equipments (UEs) which use the same codebook are confined to occupy the same time-frequency resource. So the probability of UEs with strong channel correlation paired each other is reduced, and the impact of transformation matrix on useful signal strength can be minimized. Simulation results show that the proposed algorithm can depress the multiple access interference of pairing user greatly and increase the signal to interference-plus-noise ratio of the user, and eventually improve the system throughput.