Interference Alignment For MIMO Downlink Multi-Cell Networks

MIMO(Multi-cell multiple-input multiple-output)system can efficiently enhance the capacity of the wireless networks without any additional bandwidth and transmission power. However, there exists large number of interference in the multi-cell MIMO system,such as the IUI(inter-user interference)among the users in the same cell,and the ICI(inter-cell interference) and limits the capacity of the MIMO system.As a novel interference management technique, the IA(interference technique),hasalso aroused wide concern。The key idea of IA technique is to align the interferenceinto a small subspace at each receiver, so that dimension of interference-free desireddata streams can be maximized. As a result, the research of IA technique is significantfor the wireless communication system.We investigate the IA technique for the multi-cell MIMO system with the configuration that each transmit node and receiver node have the same number of antennas. Specially,We dive the multi-cell MIMO system into several parts according to the number of users in each cell and the number of cells in the system. Furthermore, we investigate the GEVD(Generalized Eigenvalue Decomposition) based IA schemes in the different scenarios. Finally, we compute the constraint conditions for the proposed schemes, and we provide the maximum achievable Do F(degrees of freedom)for the different scenarios.The simulations results show that the proposed scheme provides a higher than or equal to that of the traditional scheme. The proposed scheme improves the system capacity.