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Performance Analysis of 5G FR2 (mmWave) Downlink 256QAM on Commercial 5G Networks

Kasidis Arunruangsirilert, Pasapong Wongprasert, Jiro Katto

TL;DR

This paper addresses whether downlink $256QAM$ on FR2 mmWave yields real-world benefits given severe path loss. It combines extensive field trials across Japan and Thailand, involving three operators and three RAN vendors in both EN-DC and NR-DC deployments, with MATLAB simulations that include $1024QAM$. The findings show that $256QAM$ provides throughput gains primarily in stationary conditions, but mobility induces higher BLER and retransmissions, limiting latency benefits and producing modest overall gains across networks. The work suggests avoiding $256QAM$ for URLLC while noting potential stationary-use cases (e.g., FWA) and highlights the need for expanded MCS tables and adaptive strategies to realize any substantial FR2 throughput benefits.

Abstract

The 5G New Radio (NR) standard introduces new frequency bands allocated in Frequency Range 2 (FR2) to support enhanced Mobile Broadband (eMBB) in congested environments and enables new use cases such as Ultra-Reliable Low Latency Communication (URLLC). The 3GPP introduced 256QAM support for FR2 frequency bands to further enhance downlink capacity. However, sustaining 256QAM on FR2 in practical environments is challenging due to strong path loss and susceptibility to distortion. While 256QAM can improve theoretical throughput by 33%, compared to 64QAM, and is widely adopted in FR1, its real-world impact when utilized in FR2 is questionable, given the significant path loss and distortions experienced in the FR2 range. Additionally, using higher modulation correlates to higher BLER, increased instability, and retransmission. Moreover, 256QAM also utilizes a different MCS table defining the modulation and code rate at different Channel Quality Indexes (CQI), affecting the UE's link adaptation behavior. This paper investigates the real-world performance of 256QAM utilization on FR2 bands in two countries, across three RAN manufacturers, and in both NSA (EN-DC) and SA (NR-DC) configurations, under various scenarios, including open-air plazas, city centers, footbridges, train station platforms, and stationary environments. The results show that 256QAM provides a reasonable throughput gain when stationary but marginal improvements when there is UE mobility while increasing the probability of NACK responses, increasing BLER, and the number of retransmissions. Finally, MATLAB simulations are run to validate the findings as well as explore the effect of the recently introduced 1024QAM on FR2.

Performance Analysis of 5G FR2 (mmWave) Downlink 256QAM on Commercial 5G Networks

TL;DR

This paper addresses whether downlink on FR2 mmWave yields real-world benefits given severe path loss. It combines extensive field trials across Japan and Thailand, involving three operators and three RAN vendors in both EN-DC and NR-DC deployments, with MATLAB simulations that include . The findings show that provides throughput gains primarily in stationary conditions, but mobility induces higher BLER and retransmissions, limiting latency benefits and producing modest overall gains across networks. The work suggests avoiding for URLLC while noting potential stationary-use cases (e.g., FWA) and highlights the need for expanded MCS tables and adaptive strategies to realize any substantial FR2 throughput benefits.

Abstract

The 5G New Radio (NR) standard introduces new frequency bands allocated in Frequency Range 2 (FR2) to support enhanced Mobile Broadband (eMBB) in congested environments and enables new use cases such as Ultra-Reliable Low Latency Communication (URLLC). The 3GPP introduced 256QAM support for FR2 frequency bands to further enhance downlink capacity. However, sustaining 256QAM on FR2 in practical environments is challenging due to strong path loss and susceptibility to distortion. While 256QAM can improve theoretical throughput by 33%, compared to 64QAM, and is widely adopted in FR1, its real-world impact when utilized in FR2 is questionable, given the significant path loss and distortions experienced in the FR2 range. Additionally, using higher modulation correlates to higher BLER, increased instability, and retransmission. Moreover, 256QAM also utilizes a different MCS table defining the modulation and code rate at different Channel Quality Indexes (CQI), affecting the UE's link adaptation behavior. This paper investigates the real-world performance of 256QAM utilization on FR2 bands in two countries, across three RAN manufacturers, and in both NSA (EN-DC) and SA (NR-DC) configurations, under various scenarios, including open-air plazas, city centers, footbridges, train station platforms, and stationary environments. The results show that 256QAM provides a reasonable throughput gain when stationary but marginal improvements when there is UE mobility while increasing the probability of NACK responses, increasing BLER, and the number of retransmissions. Finally, MATLAB simulations are run to validate the findings as well as explore the effect of the recently introduced 1024QAM on FR2.

Paper Structure

This paper contains 10 sections, 6 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Experiment Environment
  3. User Equipment (UE)
  4. Network Environment
  5. Field Test Setup
  6. Simulation Setup
  7. Results and Analysis
  8. Field Test Results
  9. Simulation Results
  10. Conclusions and Future Work

Figures (6)

  • Figure 1: Simulation Setup
  • Figure 2: Test Route of each experiment. Color legends represent 5G NR SS-RSRP.
  • Figure 3: Modulation Utilization (%) for Head-to-Head cases
  • Figure 4: Walking in Neighborhood Field Test Results
  • Figure 5: Head-to-Head Field Test Results
  • ...and 1 more figures