An Optimized Precoding Scheme based on Eigen-Channel in Interference  Alignment for Coordinated Multi-Point Transmission Systems

 Due to the widely use of frequency reuse factor one in the current and future wireless cellular systems, multi-cell interference has become a key factor constraining the system throughput. Coordinated multi-point transmission (CoMP) can efficiently reduce the interference in multi-cell system, thus improving the cell edge throughput. As a realization of CoMP, interference alignment (IA) attracts wide attention recently, which can obtain the optimal transmitting degree of freedom in multi-cell systems. A novel optimized precoding scheme is proposed for the downlink interference channel of cellular multi-input multi-output (MIMO) system. The precoding matrixes in the proposed scheme are designed by selecting the precoding vectors which are closest to the maximal eigen-channels, which improves the channel condition of the desired signal and strengthens the desired signal, in order to achieve a higher system throughput. Simulation results show that the proposed scheme can improve the throughput of the MIMO system significantly, especially for the case that the channel is spatial correlated.