Performance Evaluations of C-Band 5G NR FR1 (Sub-6 GHz) Uplink MIMO on Urban Train

TL;DR

This paper evaluates the uplink performance of C-Band 5G NR MIMO on trains, demonstrating significant throughput improvements of nearly 20% with UL-MIMO-capable devices in real-world urban train scenarios.

Contribution

It provides empirical performance comparison between UL-MIMO and traditional UL-1Tx UEs on trains, highlighting the benefits of UL-MIMO in mobile environments.

Findings

UL-MIMO-capable UEs achieve 19.8% higher average throughput on trains.

Up to 33.5% throughput improvement in favorable conditions.

A moderate correlation between downlink signal strength and uplink throughput.

Abstract

Due to the recent demand for huge Uplink throughput on Mobile networks driven by the rapid development of social media platforms, UHD 4K/8K video, and VR/AR contents, Uplink MIMO (UL-MIMO) has now been deployed on commercial 5G networks with reasonable availability of supported User Equipment (UE) for consumers. By utilizing up to 2 Tx antenna ports, UL-MIMO-capable UE promised to achieve up to two times the uplink throughput in ideal conditions, while providing improved uplink performance over UE with 1Tx in challenging conditions. In Japan, SoftBank, one of the carriers, introduced 5G Standalone (SA) services for the Fixed Wireless Access (FWA) application back in October 2021. Mobile services were commenced in May 2022, which provide UL-MIMO for supported UE on C-Band or Band n77 (3.7 GHz). In this paper, the uplink performance of UL-MIMO-capable UE will be compared against the conventional UL-1Tx UE on trains, which is the most popular method of transportation for the Japanese. The results show that UL-MIMO-capable UE delivers an average of 19.8% better throughput on moving trains with up to 33.5% in the more favorable signal conditions. A moderate relationship between downlink 5G NR SS-RSRP and uplink throughput also has been observed.