Field Test of 5G New Radio (NR) UL-MIMO and UL-256QAM for HD Live-Streaming
Kasidis Arunruangsirilert
TL;DR
The paper evaluates the practical impact of UL-MIMO and UL-256QAM on HD live-streaming over a commercial 5G SA network using RTMP. By firmware-modifying UEs to enable/disable each feature on the same device, it directly compares real-time performance, including dropped frames, disconnections, and RF metrics from CSI. UL-MIMO delivers a meaningful 17.05% gain in spectral efficiency (fewer PUSCH RBs) but increases disconnections due to per-antenna power division, while UL-256QAM improves application stability yet worsens BLER and RB usage due to limited MCS table granularity, with mixed frame results across bands. The study highlights trade-offs for live streaming, suggests HPUE as a potential mitigation, and calls for broader NG-RAN enhancements (e.g., more MCS entries) to better support higher-order modulation in evolving networks.
Abstract
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).