Optimizing the LO Distribution Architecture of mm-Wave Massive MIMO Receivers.
Optimizing the LO Distribution Architecture of mm-Wave Massive MIMO Receivers.
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发表时间：
2019-11
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通讯作者：
G. LaCaille;A. Puglielli;E. Alon;B. Nikolić;A. Niknejad
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作者：
G. LaCaille;A. Puglielli;E. Alon;B. Nikolić;A. Niknejad
毫米波无线网络在实现上有很大的困难。在这些频率下的路径损耗自然导致我们考虑具有许多元件的天线阵列。在这些阵列中，本地振荡器（LO）的产生尤其具有挑战性，因为LO规格会影响系统架构、信号处理设计和电路实现。我们深入分析了LO架构选择对毫米波大规模MIMO上行链路性能的影响。本研究的重点是涉及集中和分布式本LO产生，相关和不相关的相位噪声源，以及锁相环和载波恢复环路的带宽的权衡。我们表明，从性能和实现复杂性的角度来看，最优的LO架构使用几个锁定在低GHz范围内单个中频参考的分布式子阵列。此外，我们还表明锁相环和载波恢复环路带宽的选择对性能有很大影响；对于典型的系统参数，几十兆赫的环路带宽达到适合高阶星座的信噪比。最后，我们给出了包含LO生成系统完整模型的系统仿真，并考虑了具有16x空间复用和75 GHz载波下2 GHz信道带宽的128元阵列的情况。利用我们的优化程序，我们证明了系统可以支持64-QAM调制的16路空间复用。
Wireless networks at millimeter wavelengths have significant implementation difficulties. The path loss at these frequencies naturally leads us to consider antenna arrays with many elements. In these arrays, local oscillator (LO) generation is particularly challenging since the LO specifications affect the system architecture, signal processing design, and circuit implementation. We thoroughly analyze the effect of LO architecture design choices on the performance of a mm-wave massive MIMO uplink. This investigation focuses on the tradeoffs involved in centralized and distributed LO generation, correlated and uncorrelated phase noise sources, and the bandwidths of PLLs and carrier recovery loops. We show that, from both a performance and implementation complexity standpoint, the optimal LO architecture uses several distributed subarrays locked to a single intermediate-frequency reference in the low GHz range. Additionally, we show that the choice of PLL and carrier recovery loop bandwidths strongly affects the performance; for typical system parameters, loop bandwidths on the order of tens of MHz achieve SINRs suitable for high-order constellations. Finally, we present system simulations incorporating a complete model of the LO generation system and consider the case of a 128-element array with 16x-spatial multiplexing and a 2 GHz channel bandwidth at 75 GHz carrier. Using our optimization procedure we show that the system can support 16-way spatial multiplexing with 64-QAM modulation.