Coordinated multi-point transmission with limited feedback

Coordinated multi-point (CoMP) transmission is a promising technique to suppress inter-cell interference (ICI) in LTE-Advanced system. With perfect channel state information (CSI) at the transmitter, joint beamforming methods can be used to completely cancel ICI and significantly improve the spectrum efficiency. However, in FDD system, the transmitter can´t obtain perfect CSI to eliminate ICI, for it´s unreasonable to feed back the full channel information through the capacity limited feedback channel. In this paper, we propose a channel compression feedback scheme for FDD-CoMP system and adopt joint beamforming methods to partially mitigate ICI. In order to provide multi-cell spatial channel information and improve the feedback efficiency, the row and column number of the channel matrix are compressed using eigenmode of the user and codebook defined for LTE, respectively. Then, joint block diagonalization beamforming algorithm is applied at the transmitter to further eliminate ICI. Simulation results demonstrate that CoMP with the proposed feedback method can greatly improve the average and cell-edge spectral efficiency compared to the traditional cellular FDD system.