Real-World Performance Evaluations of Low-Band 5G NR/4G LTE 4x4 MIMO on Commercial Smartphones

2025-11-25

AI Summary

Commercial 5G user equipment (UE) widely lacks support for 4×4 MIMO in sub-1 GHz bands, limiting spectral efficiency and coverage robustness—particularly in the widely deployed Band 28 (APT 700 MHz) in Thailand. Method: This work presents the first systematic, real-world performance evaluation of 4T4R 5G NR and LTE in Band 28, leveraging flagship devices (e.g., Sony Xperia 1 III/IV) with firmware-level antenna configuration control to enforce 2Rx mode—enabling intra-device controlled comparisons. Multi-scenario reliability tests and peak throughput measurements were conducted across diverse propagation conditions. Contribution/Results: Results demonstrate that low-band 4×4 MIMO significantly enhances receiver robustness under weak-signal conditions and improves average throughput by 35–60% over 2Rx configurations. These findings empirically validate the practical capacity and coverage gains of 4×4 MIMO in wide-area, low-frequency 5G deployments, providing both methodological guidance and empirical evidence to inform spectrum-efficient network evolution strategies.

Technology Category

• Search and Optimization: Evaluation and Analysis
• Application Domains: Mobility, Driving & Flight
• Machine Learning: Mixture of Experts (MoE)

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Security and Privacy: Large-scale security measurements
• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics

Abstract

All 3GPP-compliant commercial 5G New Radio (NR)-capable UEs on the market are equipped with 4x4 MIMO support for Mid-Band frequencies (>1.7 GHz) and above, enabling up to rank 4 MIMO transmission. This doubles the theoretical throughput compared to rank 2 MIMO and also improves reception performance. However, 4x4 MIMO support on low-band frequencies (<1 GHz) is absent in every commercial UEs, with the exception of the Xperia 1 flagship smartphones manufactured by Sony Mobile and the Xiaomi 14 Pro as of January 2024. The reason most manufacturers omit 4x4 MIMO support for low-band frequencies is likely due to design challenges or relatively small performance gains in real-world usage due to the lack of 4T4R deployment on low-band by mobile network operators around the world. In Thailand, 4T4R deployment on the b28/n28 (APT) band is common on True-H and dtac networks, enabling 4x4 MIMO transmission on supported UEs. In this paper, the real-world 4x4 MIMO performance on the b28/n28 (APT) band will be investigated by evaluating the reliability test under different signal conditions and the maximum throughput test by evaluating the performance under optimal conditions, using the Sony Xperia 1 III and the Sony Xperia 1 IV smartphone. Devices from other manufacturers are also used in the experiment to investigate the performance with 2Rx antennas for comparison. Through firmware modifications, the Sony Xperia 1 III and IV can be configured to use only 2 Rx ports on low-band, enabling the collection of comparative 2 Rx performance data as a reference.

Problem

• Evaluating real-world 4x4 MIMO performance on low-band b28/n28 frequencies
• Investigating reliability and throughput differences between 4Rx and 2Rx configurations
• Assessing 4x4 MIMO benefits on commercial smartphones in Thailand's network environment

Innovation

• Evaluated low-band 4x4 MIMO performance on commercial smartphones
• Used firmware modifications to compare 2Rx and 4Rx configurations
• Tested reliability and throughput under varying signal conditions