Multi-User Scheduling and Interference Alignment for Cooperative Multi-Cell Downlink Transmissions

Interference alignment (IA) is one of the promising technologies to mitigate multi-user interference in multiple-input multiple-output (MIMO) interference channels. Recently, it has been exploited to design the transceiver to compress the inter-cell interference (ICI) in cooperative multi-cell downlink transmissions. However, most existing works focused on IA-based beamforming (IABF) design in order to compress ICI, where one transmitter has only one desired receiver and hence multi-user scheduling and corresponding multi-user interference (MUI) cancellation are not considered. In this paper, joint multi-user scheduling and IABF design are investigated for multi-user downlink interference channels. Based on the criteria of maximizing system sum rate, we proposed an algorithm that combines IABF and fast multi-user greedy search for cooperative multi-cell downlink transmissions. Both theoretical analysis and numerical simulation results are provided to demonstrate that the proposed algorithm can bring huge performance gains in multi-cell cooperative downlink transmissions.