A New Competitor in Satellite-to-Cell Technology Emerges

For most smartphone users, encountering a complete loss of signal is a rare event. For some, these interruptions may feel like a brief, welcome pause from constant notifications. However, in emergency situations, the ability to connect is critical, underscoring the importance of reliable communication.

On January 8, 2024, Elon Musk’s Starlink, leveraging T-Mobile’s network spectrum, successfully sent and received its first text message between Earth and space using a standard smartphone equipped with direct-to-cell satellite capabilities. Now, China has introduced similar technology, potentially surpassing Starlink’s innovations.

China’s Leap in Satellite Communication

Over the past two years, China Telecom, Huawei, and other collaborators have advanced the Tiantong satellite project, overcoming challenges in maintaining stable cellular connections with weak signals. By integrating satellite antennas into smartphones and unifying communication protocols, researchers have created the first smartphone capable of making direct satellite calls.

The China Telecom Satellite Application Technology Research Institute, also known as the “Satellite Institute,” developed a system that merges satellite and ground networks. This allows users to employ standard SIM cards and phone numbers for satellite calls, eliminating the need for specialized devices.

As of August 2023, Huawei had integrated L-band antennas into its devices for direct satellite-to-cell communication. Other manufacturers, including Xiaomi and Linyun, have since followed suit.

How Tiantong Satellite Communication Works

According to researcher Wang Deqian of the Satellite Institute, Tiantong satellites facilitate calls by transmitting data to a ground station, where it is processed and routed to the terrestrial network to reach the recipient. Currently, three Tiantong satellites are operational, with a fourth set to launch soon.

The origins of the Tiantong project trace back to the 2008 Sichuan earthquake, which destroyed communication infrastructure near the epicenter. The disaster highlighted the need for reliable communication systems during emergencies, prompting China to develop the Tiantong network.

Comparing Starlink and Tiantong Technologies

While both Starlink and Tiantong enable satellite-to-cell communication, their technologies differ significantly. Tiantong satellites operate in geostationary orbit, 22,000 miles (36,000 km) above Earth, covering large regions with a single satellite. These satellites prioritize low-bandwidth communication, ideal for voice calls, SMS, and light data, and use reliable L-band frequencies that function well in adverse weather.

In contrast, Starlink satellites are positioned in low-Earth orbit (200-1,200 miles) and rely on thousands of satellites to achieve global coverage. Designed for high-speed internet, they use Ku and Ka-band frequencies, which can be impacted by weather. Starlink’s direct-to-cell satellites employ terrestrial cell tower bands, ensuring compatibility with existing networks.

Overcoming Technical Challenges

Despite their fixed orbit, Tiantong satellites face challenges due to their significant distance from Earth. Researchers opted to integrate internal antennas into smartphones instead of using external ones, a decision driven by consumer preference. However, maintaining a stable connection required lowering the data transmission rate to 800 bits per second (bps) to balance power constraints and ensure voice quality.

Although 800 bps is far slower than modern internet speeds—5G can reach up to 10 Gbps—this technology is not designed for streaming but for emergency communication and basic connectivity. For adventurers in remote areas or individuals in disaster zones, satellite direct-to-cell communication is an invaluable breakthrough.

Read the orginal article on: New Atlas

Read more: Starlink Launches its First Constellation of Satellites for Direct-to-Phone Connectivity