Vladislav Zaimov stands as a leading voice in the telecommunications sector, specializing in the complex architecture of enterprise networks and the critical risk management of vulnerable infrastructure. As urban environments grow more subterranean, the demand for seamless connectivity in the most unreachable places has become a defining challenge for the industry. This conversation explores the breakthrough of TunnelStar, a collaborative effort between China Tower and Huawei, which addresses the extreme engineering and signal demands of modern 5G-A networks. By examining the shifting patterns of mobile usage and the limitations of traditional underground infrastructure, Zaimov provides a deep dive into how these technologies are reshaping the digital landscape of mass transit, summarizing the evolution of signal propagation, the logistics of tunnel deployment, and the necessity of future-proofing for the next generation of connectivity.
China’s underground transport network now spans tens of thousands of kilometers, yet these environments remain the most difficult to cover; how does the sheer scale of this infrastructure impact the pressure on modern operators?
The numbers we are seeing are truly staggering, with national subway mileage exceeding 10,000 kilometers and operational railway tunnels passing the 25,000-kilometer mark. For an operator, this isn’t just a matter of laying cable; it’s about maintaining a consistent high-speed link across a vast, moving landscape where every kilometer presents a new obstacle. The rapid expansion of these networks has created a massive backlog of connectivity needs that traditional hardware simply wasn’t designed to handle. We are seeing a point of high tension where the physical growth of the city is outpacing the capacity of the networks buried beneath it, forcing a radical rethink of how we deliver data to passengers.
Underground environments are notorious for being engineering nightmares; could you elaborate on the specific physical and logistical constraints that make upgrading tunnel networks such a daunting task?
In my experience, the “vulnerability” of these networks often comes down to the physical space—or lack thereof—within the tunnel bore. Construction teams are frequently forced into incredibly tight access windows, often restricted to just a few hours during the night when trains aren’t running. You are dealing with limited installation space where every centimeter matters, and any upgrade requires intense coordination with both railway and metro operators who prioritize safety and scheduling over signal strength. It’s a high-stakes environment where you can’t just walk in and swap out equipment; it requires compact, highly efficient hardware that can be deployed without disrupting the vital flow of city transit.
The rise of AI, livestreaming, and high-definition video calls has fundamentally shifted how we use data—what does this mean for the traditional way we approach uplink performance in confined spaces?
We have moved far beyond the era where passengers just wanted to browse a text-heavy webpage; today, they are participating in 4K video calls and using cloud-based AI applications that demand a massive amount of data sent from the device. This shift makes uplink performance the new primary metric for success, yet tunnels are historically terrible for sending signals back to the network. When you consider that TunnelStar targets these uplink-heavy services with a 9dB gain amplification, you begin to see how we can close that gap. By potentially raising uplink speeds by 20%, we are finally giving users the ability to stay productive or entertained without the frustrating lag that usually defines a subway commute.
TunnelStar introduces a waveguide approach with a specialized excitation source; how does this technology fundamentally change the way radio signals behave in an enclosed transport route?
The waveguide approach is a sophisticated way of “shaping” the radio signals so they follow the contours of the tunnel rather than bouncing uselessly off the walls. By using a specially designed excitation source, the system ensures that the radio waves move through these difficult underground spaces with much more uniformity. This helps eliminate the “dead zones” that usually occur between traditional antennas, providing a more even blanket of coverage. It’s essentially the difference between a flickering flashlight and a well-placed floodlight; the goal is to make sure the signal reaches every corner of the environment regardless of the tunnel’s shape or material.
We’ve seen claims of 10dB improvements in edge coverage and a 40% increase in user speeds—how do these metrics translate to the everyday experience of a passenger or a transit operator?
A 10dB improvement in edge coverage is significant because it specifically targets the weakest points of the network where calls usually drop or video starts to buffer. For a passenger, this means that even as they move between base stations deep underground, their connection remains stable and their data speeds feel snappy and responsive. From an operator’s perspective, a 40% jump in speed allows the network to handle many more simultaneous users during peak travel hours without the system grinding to a halt. This also opens the door for better operational services, such as enhanced security systems and connected rail applications that rely on real-time data to keep the trains running safely.
The pilot tests in Wuhan and Guangzhou covered 3.5G and 4.9G bands; what do these trials tell us about the product’s readiness for large-scale, real-world deployment across diverse tunnel shapes?
These trials are crucial because they prove the technology can handle the wider spectrums and higher frequency bands required for 5G-A. By testing in cities like Wuhan and Guangzhou, the teams were able to see how the waveguide performed in high-traffic, real-world scenarios rather than just in a controlled laboratory. The reports of stronger coverage and better deployment efficiency suggest that the system is ready to face the logistical hurdles of night-shift installations and strict safety procedures. However, the true test will be how it scales across thousands of kilometers of tunnels that vary wildly in their materials and traffic rules.
What is your forecast for 5G-A in transport networks?
I believe we are entering a phase where the transport network becomes a seamless extension of the office and the home, rather than a “black hole” for productivity. As technologies like TunnelStar mature, we will see operators move away from stop-gap measures and toward infrastructure that inherently supports future evolutions, including 6G. This flexibility is vital because it prevents the need for repeated, expensive rebuilds every time a new frequency band is introduced. Ultimately, the success of these networks will depend on how well we can balance the massive costs of deployment with the undeniable need for high-capacity, reliable underground connectivity.
