Massive multiple-input multiple-output (MIMO) is considered as a breakthrough technology in 5G and beyond 5G systems. Some of its main advantages are providing high spectral efficiency to many users simultaneously in the same time-frequency blocks, strong directive signals towards short-range areas and little interference leaks. However, while massive MIMO exhibits interesting benefits, it is important to investigate its main gains through real deployment scenarios in an operator’s infrastructure. In this paper, we focus on performance comparisons of traditional frequency-division duplex (FDD)-based MIMO and 2.6 GHz Time-division duplex (TDD)-based massive MIMO deployments through experimental analysis under different spectrum and bandwidth in a total of three separate sites and one co-site in an operational infrastructure of an operator in Turkey. We also provide design guidelines and requirements for massive MIMO network deployment and proper acceptance of Key Performance Indicators (KPIs) collection and comparisons criteria. Our experimental results reveal up to 66%, 56% and 23% performance benefits in terms of downlink (DL) cell throughput of 2.6 Ghz TDD-based massive MIMO compared to FDD-based MIMO sites in 800 Mhz (site with approximately same number of User Equipment (UEs) compared with TDD massive MIMO), 1800 Mhz (site with higher number of UEs compared with TDD massive MIMO) and 2600 Mhz (site with lower number of UEs compared with TDD massive MIMO) respectively each having 10 Mhz bandwidth. On the other hand, LTE 1800 Mhz FDD MIMO at 20 Mhz can yield higher user throughput values in comparison to 2.6 GHz TDD-based massive MIMO at 10 Mhz. We also observed that the maximum paired layer reached 14 layers in DL of TDD-based massive MIMO. At the end of the paper, we address the main observations and takeaways of TDD-based massive MIMO deployments.

大规模多输入多输出（MIMO）被认为是5G和5G系统之外的一项突破性技术。它的一些主要优点是在相同的时频块中同时为许多用户提供高频谱效率，指向短距离区域的强指令信号以及很少的干扰泄漏。但是，尽管大规模MIMO具有有趣的优势，但重要的是要通过在运营商基础架构中的实际部署场景来研究其主要收益。在本文中，我们通过在总共三个不同的频谱和带宽下进行实验分析，着重于比较基于传统频分双工（FDD）的MIMO和基于2.6 GHz时分双工（TDD）的大规模MIMO部署的性能。运营商的运营基础架构中的一个站点和一个共同站点。我们还提供了用于大规模MIMO网络部署的设计准则和要求，以及对关键性能指标（KPI）收集和比较标准的正确接受。我们的实验结果表明，相比于800 Mhz的基于FDD的MIMO站点，基于2.6 Ghz TDD的大规模MIMO的下行链路（DL）小区吞吐量，分别具有高达66％，56％和23％的性能优势。用户设备（UE）与TDD大规模MIMO相比），1800 Mhz（与TDD大规模MIMO相比具有较多UE的站点）和2600 Mhz（与TDD大规模MIMO相比具有较少UE的站点）均具有10 Mhz带宽。另一方面，与10 Mhz的基于2.6 GHz TDD的大规模MIMO相比，20 Mhz的LTE 1800 Mhz FDD MIMO可以产生更高的用户吞吐量值。我们还观察到，在基于TDD的大规模MIMO的DL中，最大配对层达到14层。在本文的最后，我们讨论了基于TDD的大规模MIMO部署的主要观察和收获。