论文标题
具有低容量的Fronthaul链接和低分辨率ADC/DACS的无细胞MMWAVE巨大的MIMO系统
Cell-Free MmWave Massive MIMO Systems with Low-Capacity Fronthaul Links and Low-Resolution ADC/DACs
论文作者
论文摘要
在本文中，我们考虑了具有低容量的Fronthaul链路和低分辨率类似于数字到数字转换器/数字到数字到ANALOG转换器（ADC/DACS）（ADC/DACS），我们考虑了无细胞毫米波（MMWAVE）的上行链路通道估计阶段和下行链路数据传输阶段。在无细胞的大型MIMO中，一个控制单元决定基带的地理规模处理，而基站通过Fronthaul链路与控制单元进行通信。与以前的大多数无细胞大型MIMO的作品不同，具有有限的容量较高的Fronthaul链接，我们认为通常情况下，Fronthaul容量和ADC/DAC分辨率不一定是相同的。特别是，在基于信息理论参数和加性量化噪声模型（AQNM）对每个量子建模的情况下，领先的压缩和ADC/DAC量化是独立发生的。然后，我们解决了旨在最大程度地减少独立和相同分布（I.I.D.）和彩色压缩噪声案例的通道估计误差的代码书设计问题。另外，我们提出了一种交替的优化方法（AO）方法来解决最大的公平性问题。本质上，AO方法在两个子问题之间交替，与电源分配和代码书设计问题相对应。为零强度（ZF）预编码器提出的AO方法保证会收敛，而最大比率传输（MRT）的AO方法没有这样的保证。最后，根据能量和光谱效率，通过模拟结果评估了所提出的方案的性能。数值结果表明，ZF预码器的提议方案产生的光谱和能效率比最佳基线的方案高28％和15％。
In this paper, we consider the uplink channel estimation phase and downlink data transmission phase of cell-free millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) systems with low-capacity fronthaul links and low-resolution analog-to-digital converters/digital-to-analog converters (ADC/DACs). In cell-free massive MIMO, a control unit dictates the baseband processing at a geographical scale, while the base stations communicate with the control unit through fronthaul links. Unlike most of previous works in cell-free massive MIMO with finite-capacity fronthaul links, we consider the general case where the fronthaul capacity and ADC/DAC resolution are not necessarily the same. In particular, the fronthaul compression and ADC/DAC quantization occur independently where each one is modeled based on the information theoretic argument and additive quantization noise model (AQNM). Then, we address the codebook design problem that aims to minimize the channel estimation error for the independent and identically distributed (i.i.d.) and colored compression noise cases. Also, we propose an alternating optimization (AO) method to tackle the max-min fairness problem. In essence, the AO method alternates between two subproblems that correspond to the power allocation and codebook design problems. The AO method proposed for the zero-forcing (ZF) precoder is guaranteed to converge, whereas the one for the maximum ratio transmission (MRT) precoder has no such guarantee. Finally, the performance of the proposed schemes is evaluated by the simulation results in terms of both energy and spectral efficiency. The numerical results show that the proposed scheme for the ZF precoder yields spectral and energy efficiency 28% and 15% higher than that of the best baseline.
