Delivering fast and stable WiFi on trains is a well-known challenge, not least in geographically demanding environments. Could modern Low Earth Orbit (LEO) satellite communication be the next major technological leap for the railway industry? To understand the true potential of the technology, we at Oxyfi, in close collaboration with Region Jämtland Härjedalen and Norrtåg AB, have run a project that began in late 2023 to explore how Starlink performs in a demanding train environment
The tests were conducted during regular traffic along the long routes Storlien–Sundsvall–Umeå and Umeå–Luleå, an area spanning approximately 1,000 kilometers.
Here, we share our most important insights on how LEO satellite and mobile networks can work together to create the next generation of onboard internet connectivity.
A Powerful Combination of Technologies
Relying on a single connectivity technology is rarely sufficient for fast-moving vehicles traveling across large geographic areas. In our project, the Starlink receiver was therefore used in symbiosis with existing 4G and 5G connections from Telia and Telenor.
To maximize performance, data traffic was smartly distributed using our proprietary technology for the aggregation of fast-moving mobile data links, implemented via our roof-mounted OxBox solution. The test environment, a Coradia X62 regional train running at speeds up to 180 km/h, provided an excellent platform to observe how the technology handles high speeds and varied terrain.
Significant Capacity Increase Along Northern Tracks
One of the clearest lessons is that Starlink serves as a very strong complement to today’s mobile networks. Instead of competing with 4G/5G, the satellite technology fills in the gaps:
- On the Storlien–Sundsvall–Umeå route, Starlink added an average of about 180 Mbps on top of the mobile networks’ existing 308 Mbps
- This resulted in an impressive average capacity increase of 58 percent
- Between Umeå and Luleå, the effect was even greater; there, Starlink added about 216 Mbps to the mobile networks’ 278 Mbps, corresponding to a capacity increase of about 78 percent
- In total, the combined capacity across both routes averaged nearly 500 Mbps
- At certain measurement points, the total capacity exceeded 1 Gbps
A key strategic discovery is that Starlink often adds high capacity in the geographical areas where traditional mobile networks underperform. The combination of technologies thus provides a much smoother and more comprehensive onboard connection than any of the individual links can offer on their own.
Low Latency (RTT) and High User Experience
Performance ultimately comes down to how the passenger actually experiences the WiFi service. To measure this, we installed a separate test-robot onboard that continuously evaluated the user experience (Mean Opinion Score, MOS) for services like Netflix, Microsoft Teams, and Google Meet. The measurements showed good to very good perceived quality along almost the entire test route.
When Starlink was available, the average latency was only 46–48 milliseconds. This is fully on par with, and in some cases even lower than, the corresponding values for the tested 4G/5G networks.
The Challenges: Tunnels and the Need for Lightning-fast Aggregation
No single technology is however without limitations. LEO satellites require a clear line of sight to the sky, which means the connection breaks the moment the train enters a tunnel. Viaducts and other brief obstacles can also cause temporary outages:
- On the highly tunnel-dense route between Kramfors and Umeå, Starlink could only be actively used for about 50 percent of the time
- In contrast, availability was a full 99.6 percent on the Umeå–Luleå route, which largely lacks tunnels
- Across the entire Storlien–Sundsvall–Umeå route, Starlink was active for about 89 percent of the journey
These figures highlight one reason why Starlink should not be seen as a standalone replacement for mobile networks. Furthermore, satellite connectivity has an “on or off” character. Unlike mobile links — which often maintain a connection, albeit with degraded quality, when radio conditions becomes difficult — the satellite link is binary. This places extremely high demands on the train’s aggregation function, which must be able to immediately adapt when the line of sight to the satellites is obstructed so that passengers do not notice the interruption.
Withstanding the Nordic Climate?
An important question for railway operators is always the durability of the equipment. In our project, the Starlink receiver was equipped with a custom-made stainless steel enclosure and mechanical mounting. After being mounted on the train roof for two northern Swedish winters, we have observed absolutely no problems. The experience shows that the equipment can handle the highly demanding environment of trains in northern Sweden.
Conclusion: The Hybrid Solution is the Way Forward
The insights from over 1,000 kilometers of northern railway over extended testing periods speak for themselves. The most optimal technical solution for regional trains on these routes is a hybrid approach — a combination of high-capacity satellite connectivity and multi-operator mobile networks. With an intelligent and fast aggregation function in place, we can combine the strengths of the different links while simultaneously mitigating their respective weaknesses. The result is a stable, fast, and modern internet experience for the train passengers of tomorrow.
Do you have thoughts or questions about satellite connectivity on trains, or how to maximize performance with multi-WWAN aggregation? Don’t hesitate to reach out to us at Oxyfi for further discussion!
Trademark notice:
Starlink, Google, Microsoft, Netflix, Telia, and Telenor are independent companies and registered trademarks belonging to their respective owners. We at Oxyfi are an independent company that uses and evaluates their services and products as part of our tests and technical solutions.