5G Quality of Service in Bangkok and Metropolitan Areas: Revisiting BTS Skytrain Station Areas

This study compares the 5G service quality of two leading Thai mobile operators around BTS Skytrain stations in Bangkok, revealing that despite a decline in upload speeds and an increase in latency between 2021 and 2023, the overall network performance has significantly improved.

The Gist

Imagine you bought a brand-new, high-speed sports car in 2021. It was fast, responsive, and felt like the future. Now, it's 2023. You hop back in, expecting it to be even faster because the roads have improved and more people are using them. But instead, the car feels sluggish, takes longer to accelerate, and the engine seems to be struggling.

That is essentially the story of this research paper. The authors are like mechanics who went back to the same test track (Bangkok's BTS Skytrain stations) to see how the "engine" of Thailand's 5G internet is running two years later.

Here is the breakdown of their findings in plain English:

1. The Setup: A "Time Travel" Test

The researchers decided to revisit the exact same spots they tested in May 2021. These spots were the platforms and waiting areas of the BTS Skytrain stations in Bangkok.

• Why there? These stations are like the busiest subway stops in the city, packed with people. If the internet works well there, it's a good sign.
• The Tools: In 2021, they used one specific smartphone. In 2023, they had to use a different phone (because the old one was discontinued), but they made sure to account for the fact that the new phone might be slightly different.
• The Goal: They wanted to see if the internet speed was getting better or worse, and to check if the official reports from a global company called "Opensignal" matched what they were seeing with their own eyes.

2. The Results: The "Traffic Jam" Effect

When they ran the tests in 2023, the results were a bit of a shock. Even though 5G is supposed to be the "fast lane" of the internet, it actually got slower compared to 2021.

• Downloading (Getting data): Imagine downloading a movie. In 2021, the average speed was like a highway cruising at 196 Mbps. By 2023, that speed dropped to 140 Mbps.
  • The Twist: One of the two big phone companies (MNO2) actually got faster, like they fixed a pothole on their road. But the other company (MNO1) got significantly slower.
• Uploading (Sending data): Imagine sending a huge video file to a friend. In 2021, it was like a fast courier (62.6 Mbps). In 2023, the courier slowed down to 52.0 Mbps.
• Latency (The "Reaction Time"): This is the most important part for gamers and video callers. It's the time it takes for a signal to say "Hello" and get a "Hello" back.
  • In 2021, the reaction was snappy: 14.9 milliseconds.
  • In 2023, it felt sluggish: 23.3 milliseconds.
  • Analogy: In 2021, you waved at a friend across the street and they waved back instantly. In 2023, there was a noticeable pause before they waved back.

3. Why Did It Get Slower?

The authors suggest a few reasons, similar to why a highway might get clogged even if you add more lanes:

• Too Many Cars: More people have 5G phones now. It's like a highway that was empty in 2021 but is now packed with rush-hour traffic in 2023. Everyone is trying to use the same bandwidth.
• Business Decisions: Sometimes, companies limit how fast you can go to manage costs or encourage you to buy a more expensive plan.
• The "Opensignal" Check: The researchers compared their data to the global company Opensignal. They found that while Opensignal's numbers were generally lower (perhaps because they tested in more random places), the trend was the same: Speeds are going down, and delays are going up.

4. The Big Takeaway

The main lesson here is that more technology doesn't always mean better performance immediately.

Even though 5G coverage has expanded (more stations have it), the actual experience for the user in these busy areas has gotten worse since 2021. It's like building a bigger stadium but not adding enough exits; when the crowd gets too big, everyone gets stuck.

In summary:

• 2021: Fast, snappy, and efficient.
• 2023: Slower, slightly more delayed, and struggling with the crowd.
• The Verdict: The 5G network in Bangkok is still good, but it's not living up to the "super-fast" hype it had two years ago, likely because too many people are using it at once.

The authors hope that in the future, they can test this while people are moving (like on a train) rather than standing still, and check other factors like how often the connection drops out, to get the full picture.

Technical Summary

1. Problem Statement

Despite the rapid deployment of 5G networks in Thailand since 2020, there is a lack of credible, independent, and up-to-date official reports on the actual Quality of Service (QoS) experienced by users. Existing reports, such as those from Opensignal, have faced skepticism regarding their methodology and accuracy compared to end-user experiences. Furthermore, while theoretical 5G capabilities promise high speeds and low latency, real-world performance is influenced by factors like subscriber density, network congestion, and infrastructure maturity. The authors identified a critical gap: there was no recent comparative study evaluating the evolution of 5G performance in high-density urban areas (specifically Bangkok) between the early adoption phase (2021) and the current maturity phase (2023).

2. Methodology

The study employed a comparative field testing approach to evaluate the QoS of the two leading Mobile Network Operators (MNOs) in Thailand.

• Study Area: The research focused on 60 BTS Skytrain stations in Bangkok and its metropolitan area. These locations were chosen due to their high passenger traffic (approx. 200,000 daily) and their status as critical commercial and residential hubs.
• Data Collection Periods:
  • Baseline (2021): Data randomly selected from a dataset collected in May 2021.
  • Current (2023): New data collected between March and April 2023.
• Test Configuration:
  • Test Mode: Stationary tests conducted at specific points on the platform level and concourse level of each station.
  • Devices:
    • 2021: Huawei smartphone with Kirin 990 5G chipset.
    • 2023: Android smartphone with MediaTek Dimensity 810 chipset.
    • Note: The authors acknowledged the device change but utilized statistical methods to mitigate chipset variance impacts.
  • Applications:
    • Opensignal: Used for primary speed and latency testing to allow direct comparison with industry reports.
    • nPerf: Used to verify the specific network technology (5G NSA vs. 4G LTE) connected during each session, as Opensignal does not always disclose the underlying radio access technology.
• Metrics Evaluated: Download Speed (DL), Upload Speed (UL), and Latency.
• Statistical Analysis: The authors applied t-tests to compare the 2021 and 2023 datasets against nine specific hypotheses to determine statistical significance (p-value < 0.05).

3. Key Contributions

• Longitudinal Performance Analysis: This is one of the few studies to provide a direct "before-and-after" comparison of 5G performance in Thailand, highlighting the degradation of service quality over a two-year period despite increased coverage.
• Validation of Industry Reports: The study validates the general trends reported by Opensignal (declining speeds) while demonstrating that the authors' field measurements yielded higher absolute values than the commercial reports, suggesting potential discrepancies in commercial reporting methodologies.
• Granular Location Data: By focusing specifically on BTS Skytrain stations, the study provides insights into 5G performance in high-density, high-mobility urban corridors, a scenario often overlooked in nationwide averages.
• Technology Correlation: The study correlated performance drops with the percentage of 5G Non-Standalone (NSA) connections, revealing that higher 5G coverage percentages did not equate to better performance.

4. Key Results

The study revealed a significant decline in 5G performance between 2021 and 2023 across both major MNOs.

• Download Speed (DL):
  • Overall Average: Dropped from 196.4 Mbps (2021) to 140.4 Mbps (2023).
  • MNO1: Decreased drastically from ~310 Mbps to ~166 Mbps.
  • MNO2: Interestingly, MNO2 improved from ~85 Mbps to ~144 Mbps, though the combined average still fell.
• Upload Speed (UL):
  • Overall Average: Dropped from 62.6 Mbps (2021) to 52.0 Mbps (2023).
  • Both MNOs showed a decline in upload performance.
• Latency:
  • Overall Average: Increased (worsened) from 14.9 ms (2021) to 23.3 ms (2023).
  • Higher latency indicates reduced network responsiveness, which is critical for real-time applications.
• Statistical Significance: All t-tests confirmed that the differences between 2021 and 2023 data were statistically significant (p < 0.001 for most metrics).
• Coverage vs. Performance Paradox: Table 3 shows that 5G NSA coverage increased significantly (from ~69% to ~93% for MNO1 and ~62% to ~92% for MNO2), yet performance metrics declined.

5. Significance and Discussion

• Network Congestion: The authors attribute the performance degradation to the rapid increase in 5G subscribers and User Equipment (UE) density, which likely exceeds the capacity of the current infrastructure, leading to resource contention.
• Business and Marketing Factors: The study suggests that MNOs may be throttling speeds or prioritizing marketing over infrastructure upgrades to manage costs, or that the "unlimited" data packages are subject to hidden fair usage policies that impact speed.
• Reliability of Commercial Reports: While the study confirms the trend of declining speeds found in Opensignal reports, the absolute values measured were consistently higher. This implies that commercial crowd-sourced reports might underestimate actual network capabilities in specific high-density zones or suffer from different sampling biases.
• Limitations: The study is limited to stationary tests in specific urban locations and does not account for mobility (handovers while moving) or other QoS parameters like packet loss and jitter. Additionally, the change in smartphone hardware between test years introduces a variable, though the authors attempted to control for this.

Conclusion: The paper concludes that while 5G coverage in Bangkok has expanded significantly, the Quality of Service has deteriorated since 2021. The theoretical potential of 5G is not being realized in practice due to network congestion and infrastructure limitations, necessitating further investment in network capacity and optimization.