"While browsing Moments, the plane is passing through the clouds" - this seemingly simple operation is actually backed by complex air-ground communication technology. This article dissects the two core technologies of aircraft WiFi (ATG vs satellite), guiding you through how to achieve "never disconnection" at an altitude of 10,000 meters.
Technical principle: Ground base stations vs. space satellites
ATG (Air-to-Ground Broadband)
Dedicated base stations are deployed along the flight path on the ground. The signal is "transmitted upward" to the aircraft's belly antenna and then converted into WiFi through the on-board server.
Advantages: High bandwidth (3.6Mbps downlink), low latency (within 50ms), and cost is only one-third of that of satellites.
Limitation: It only covers land routes and cannot be used for transoceanic flights.
Satellite communication
The aircraft connects to geosynchronous orbit or low-orbit satellites (such as SpaceX Starlink) via its top antenna, and the signal needs to travel 22,000 kilometers.
The early L-band satellite bandwidth was only 100Kbps. Currently, the single-carrier rate of KU/ Ka-band satellites has reached 100Mbps, and in the future, starlink can achieve 220Mbps.
Advantages: Global coverage, suitable for transoceanic flights; Limitations: High latency (600ms+), expensive cost.
Actual scenario: How to choose domestic airlines?
China Eastern Airlines/Juneyao Airlines: Adopting a Ku-band satellite +ATG hybrid solution, the measured download speed on the Beijing-Shanghai route is 15-20Mbps, and it supports 4K video streaming.
Shenzhen Airlines: Deploying 5G-ATG technology, covering through ground base stations in a "relay" manner, costs reduced by 40%, and plans to popularize it to all national routes by 2026.
International flights: United Airlines and Emirates have piloted Starlink, with a measured delay of 80ms, providing a 5G experience close to that on the ground.
Future trends: Faster, more stable, and cheaper
5G-ATG: China Mobile's pilot program shows that the peak rate of a single aircraft is 420Mbps, with a coverage radius of 300km. It is expected to be commercially available on a large scale in 2025.
Low-orbit satellites: SpaceX Starlink has deployed 5,144 satellites. By 2023, it had over 2 million users and plans to achieve global flight coverage by 2027.
Free service: China Eastern Airlines has launched a "Half-year in-flight WiFi card" for 186 yuan. Juneyao Airlines' special offer package has increased the conversion rate by 80%. The business model has shifted from "hourly charging" to "monthly data package".
Airplane WiFi is not magic but a "coordinated operation" between ground base stations and space satellites. The next time you take off, why not take a look outside the porthole - those invisible signals are connecting your cloud life.
