Modulation compression is a technique considered in the recent Open-RAN (O-RAN) framework, which has continued the 3GPP effort toward the definition of new virtualized and multi-vendor RAN architectures. Basically, fronthaul compression is achieved by means of reducing the modulation order, thus enabling a dramatic reduction of the required fronthaul capacity with a simple technique. In this work, we provide a survey of the architectures, functional splits, and fronthaul compression techniques envisioned in 3GPP and O-RAN. Then we focus on assessing the trade-offs that modulation compression exhibits in terms of reduced fronthaul capacity vs. the impact on the air interface performance, through a dynamic multi-cell system-level simulation. For that, we use an ns-3-based system-level simulator compliant with 5G New Radio (NR) specifications and evaluate different traffic load conditions and NR numerolo-gies. In a multi-cell scenario, our results show that an 82 percent reduction of the required fronthaul capacity can be achieved with negligible air interface performance degradation by reducing the modulation order down to 64-QAM for different numerologies and load conditions. A higher modulation order reduction without degradation is permitted in low/medium traffic loads (reaching up to 94 percent fronthaul capacity reduction).

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下一代RAN中的调制压缩：空中接口和前传权衡

调制压缩是最近的Open-RAN（O-RAN）框架中考虑的一种技术，该框架继续了3GPP努力来定义新的虚拟化和多供应商RAN体系结构。基本上，通过减少调制阶数来实现前传压缩，从而可以通过简单的技术显着降低所需的前传容量。在这项工作中，我们提供了对3GPP和O-RAN中构想的体系结构，功能拆分和前传压缩技术的概述。然后，我们专注于通过动态多小区系统级仿真，就减少的前传容量与对空口性能的影响而言，评估调制压缩表现出的权衡。为了那个原因，我们使用符合5G新无线电（NR）规范的基于ns-3的系统级模拟器，并评估不同的流量负载条件和NR数值。在多小区场景中，我们的结果表明，通过将调制阶数降低到64-QAM（针对不同的数字和负载条件），可以将所需的前传容量减少82％，同时将空中接口的性能降低到可以忽略的程度。在中低流量负载下，可以实现更高的调制阶数降低而不会降低性能（前传容量降低达94％）。我们的结果表明，通过将调制阶数降低到64-QAM（针对不同的数值和负载条件），可以将所需的前传容量减少82％，同时将空中接口的性能降低到可以忽略的程度。在中低流量负载下，可以实现更高的调制阶数降低而不会降低性能（前传容量降低达94％）。我们的结果表明，通过将调制阶数降低到64-QAM（针对不同的数值和负载条件），可以将所需的前传容量减少82％，同时将空中接口的性能降低到可以忽略的程度。在中低流量负载下，可以实现更高的调制阶数降低而不会降低性能（前传容量降低达94％）。