毫米波大规模MIMO系统中的预编码技术

[摘要] 大规模多输入多输出（MIMO）技术能够大幅度提升系统容量，降低不同用户间的干扰，但因其系统中信道维度高、信道估计和预编码算法复杂等因素，使得系统软硬件开销都会增大。将大规模MIMO系统的预编码算法分为数字、模拟和混合3种类型，并对3类预编码算法进行了归纳对比，总结出不同预编码算法的优缺点和适用场景。将信道估计方案分为训练估计和盲估计，归纳总结了2类方案的优缺点，并指出合理利用大规模MIMO的信道稀疏性能够改善信道估计的质量，减少估计开销。

[关键词] 毫米波；大规模MIMO；预编码算法；信道估计

[Abstract] Massive multiple-input multiple-output (MIMO) technology can greatly increase the system capacity and reduce the interference between different users. However, due to the high channel dimension, complex channel estimation and precoding algorithms, the hardware and software overhead of the system will increase. In this paper, the precoding algorithms are classified into three types: digital algorithm, analog algorithm and hybrid algorithm. The advantages and disadvantages of different algorithms and applicable scenarios are summarized and compared. In addition, the channel estimation scheme is divided into training-estimation and blind-estimation, and the characteristics of the two schemes are compared. It is pointed out that the channel sparsity of massive MIMO can improve the quality of channel estimation and reduce the estimation cost.

[Keywords] millimeter wave; massive MIMO; precoding algorithms; channel estimation