Massive multi-user multiple-input multiple-output (MU-MIMO) wireless systems operating at millimeter-wave (mmWave) frequencies enable simultaneous wideband data transmission to a large number of users. In order to reduce the complexity of MU precoding in all-digital basestation architectures, we propose a two-stage precoding architecture that first performs precoding using a sparse matrix in the beamspace domain, followed by an inverse fast Fourier transform that converts the result to the antenna domain. The sparse precoding matrix requires a small number of multipliers and enables regular hardware architectures, which allows the design of hardware-efficient all-digital precoders. Simulation results demonstrate that our methods approach the error-rate of conventional Wiener filter precoding with more than 2x reduced complexity.

翻译：在毫米波(mmWave)频率运行的大规模多用户多输入多输出无线系统(MU-MIMO)能够同时向大量用户传输宽带数据。为了降低所有数字基站结构中MU预编码的复杂性,我们提议了两阶段预编码结构,首先使用波束空间范围内的稀薄矩阵进行预编码,然后是逆向快速的Fourier变换,将结果转换到天线域。稀有的预编码矩阵需要少量的乘数,并能够正常的硬件结构,从而能够设计具有硬件效率的所有数字预编码器。模拟结果表明,我们的方法是采用常规Wiener过滤预编码的错误率,而复杂性则减少2x以上。