Abstract: Focused on the problems of high hardware cost and high system overhead in the millimeter-Wave Massive Multi-Input Multi-Output (mmWave Massive MIMO) system, an Orthogonal Matching Pursuit based on improved Intelligent Water Drop (IWD-OMP) hybrid precoding algorithm was proposed. Firstly, based on Orthogonal Match Pursuit (OMP) algorithm, the precoding matrix was solved. Secondly, the improved Intelligent Water Drop (IWD) algorithm was adopted to calculate the global optimal index vector in the matrix. Finally, the matrix solved by this method did not need to construct the candidate matrix in advance, which was able to save the system resources and reduce the complexity of matrix calculation. Experimental results demonstrate that when the number of transmitting antennas is 128 and the signal-to-noise ratio is 28 dB, compared with the OMP algorithm, the proposed method has the system achievable sum rate performance improved by about 7.71%, when the signal-to-noise ratio is 8 dB, the proposed method has the bit error rate reduced by about 19.77%. In addition, the proposed precoding algorithm has strong robustness to the imperfect Channel State Information (CSI) in the real channel environment. When the signal-to-noise ratio value is 28 dB, the proposed method has the system achievable sum rate decreased by about 1.08% for imperfect CSI compared with that for perfect CSI.

Key words: millimeter-Wave massive Multi-Input Multi-Output (mmWave Massive MIMO) system, hybrid precoding, intelligent water drop, Orthogonal Matching Pursuit (OMP), imperfect Channel State Information (CSI)

摘要： 针对毫米波大规模多输入多输出（mmWave Massive MIMO）系统硬件成本高、系统开销大等问题，提出一种基于改进智能水滴的正交匹配追踪（IWD-OMP）混合预编码算法。首先，基于正交匹配追踪（OMP）算法求解预编码矩阵；其次，采用改进的智能水滴（IWD）算法求解矩阵中全局最优的索引向量；最后，通过此方法求解的矩阵无须提前构造候选矩阵，可以达到节约系统资源、降低矩阵计算复杂度的目的。实验结果表明，当发送端天线数为128，信噪比为28 dB时，与OMP算法相比，该方法的系统可达和速率提高了约7.71%；当信噪比为8 dB时，该方法的系统误码率降低约19.77%。此外，所提预编码算法对实际信道环境中非完全信道状态信息（CSI）具有鲁棒性，当信噪比取值为28 dB时，相较于完全CSI，该方法对非完全CSI的可达和速率降低了约1.08%。

关键词: 毫米波大规模多输入多输出系统, 混合预编码, 智能水滴, 正交匹配追踪, 非完全信道状态信息