For the next generation wireless networks, backhaul links with data rates of several Gbit / s are required. Line-of-Sight-MIMO with optimally arranged antennas can exploit the full multiplexing gain of orthogonal MIMO streams to achieve high throughput, as shown in recent works utilizing the 60 GHz mm wave band. In contrast, conventional MIMO systems operating at sub-6 GHz carrier frequencies, as utilized in modern WLAN networks, rely on rich scattering channels to enable reliable transmissions. In this work, we explore the feasibility of applying the LoS-MIMO concept to wireless single-carrier links operating at sub-6 GHz frequencies. For this, we investigate the sub-6 GHz LoS-MIMO channel in a 4 × 4 MIMO configuration by performing measurements in an anechoic chamber and an outdoor backhaul-like environment. In addition, different adaptive equalizers are evaluated. The results show, that the LoS-MIMO concept holds for sub-6 GHz frequencies both in pure LoS and in outdoor environments. It provides high multiplexing gain; however, the multipath propagation limits the potential performance of the equalizers in terms of achievable BER.

中文翻译：

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低于6 GHz载波频率的视线多输入多输出（MIMO）传输的实验评估

对于下一代无线网络，需要具有几Gbit / s数据速率的回程链路。如最近使用60 GHz mm波段的工作所示，具有最佳布置天线的视线MIMO可以利用正交MIMO流的全多路复用增益来实现高吞吐量。相反，在现代WLAN网络中使用的，工作在6 GHz以下子载波频率的常规MIMO系统依赖于丰富的散射信道来实现可靠的传输。在这项工作中，我们探索了将LoS-MIMO概念应用于在6 GHz以下频率运行的无线单载波链路的可行性。为此，我们通过在消声室和类似室外回程的环境中进行测量来研究4×4 MIMO配置中的6 GHz以下LoS-MIMO信道。此外，评估了不同的自适应均衡器。结果表明，LoS-MIMO概念在纯LoS和室外环境中都适用于6 GHz以下的频率。它提供了很高的多路复用增益；然而，就可实现的BER而言，多径传播限制了均衡器的潜在性能。