The exponential growth of User-Generated Content (UGC), especially High-Definition (HD) live video streaming, places a significant demand on the uplink capabilities of mobile networks. To address this, the 5G New Radio (NR) standard introduced key uplink enhancements, including Uplink Multi-Input Multi-Output (UL-MIMO) and Uplink 256QAM, to improve throughput and spectral efficiency. However, while the benefits of these features for raw data rates are well-documented, their practical impact on real-time applications like live-streaming is not yet well understood. This paper investigates the performance of UL-MIMO and UL-256QAM for HD live-streaming over a commercial 5G network using the Real-Time Messaging Protocol (RTMP). To ensure a fair assessment, we conduct a comparative analysis by modifying the modem firmware of commercial User Equipment (UE), allowing these features to be selectively enabled and disabled on the same device. Performance is evaluated based on key metrics, including dropped video frames and connection stability. Furthermore, this study analyzes 5G Radio Frequency (RF) parameters to quantify the spectral efficiency impact, specifically examining metrics derived from the Channel State Information (CSI) framework, including Reference Signal Received Power (CSI-RSRP), Reference Signal Received Quality (CSI-RSRQ), and Signal-to-Interference-plus-Noise Ratio (CSI-SINR).

翻译：用户生成内容（UGC）的指数级增长，特别是高清（HD）实时视频流媒体，对移动网络的上行链路能力提出了重大需求。为应对这一挑战，5G新空口（NR）标准引入了关键的上行链路增强技术，包括上行多输入多输出（UL-MIMO）和上行256QAM，以提升吞吐量和频谱效率。然而，尽管这些特性对原始数据速率的益处已有充分记载，但其对实时应用（如直播流媒体）的实际影响尚未得到充分理解。本文通过商用5G网络，利用实时消息传输协议（RTMP），研究了UL-MIMO和UL-256QAM在高清直播流媒体中的性能。为确保公平评估，我们通过修改商用用户设备（UE）的调制解调器固件，在同一设备上选择性启用和禁用这些特性，进行了对比分析。性能评估基于关键指标，包括视频丢帧率和连接稳定性。此外，本研究分析了5G射频（RF）参数以量化频谱效率影响，特别考察了基于信道状态信息（CSI）框架导出的指标，包括参考信号接收功率（CSI-RSRP）、参考信号接收质量（CSI-RSRQ）和信号与干扰加噪声比（CSI-SINR）。