Practical Satellite-to-Cellular Communication Is Coming Closer to Reality

Satellite or cellular? Why not both?

A handful of vendors are racing to market with satellite connectivity for cell phones. In January 2024, Starlink sent and received text messages between 4G/LTE mobile phones via satellite. In April, Lynk Global announced a sat2phone contract with the Department of Defense for text messaging, emergency broadcast alerts and other broadcast services. Amazon, Apple, AST SpaceMobile and Huawei are also working on satellite-to-cellular projects.

These initiatives take advantage of lower satellite costs and advances in cellular technology. Low-Earth Orbit (LEO) satellites, which operate at about 300 miles from the Earth’s surface, can better detect mobile phone signals and handle growing amounts of traffic. They also provide faster data transfer rates, greater bandwidth and lower latency than legacy satellites. However, there are still several hurdles to overcome before everyone has a satellite phone in their pocket.

Overcoming Obstacles

Satellites travel thousands of miles per hour, giving them limited time to connect with any particular phone. As a result, traditional satellite phones have thick antennas and require clear lines of sight to satellites. Even then, they take time to acquire a signal. These complexities are fine for remote and emergency communications but hardly match the cell phone experience most of us are used to.

No one wants to go back to chunky cell phones, so developers are redesigning satellites to be more like cell towers. Cellular-compatible satellites have much larger antennas to detect the weaker signals from mobile phones. Improved beamforming can also help satellites better direct their signals toward a specific device.

So far, however, these techniques are only practical for text messaging and broadcast services. Satellite-to-cellular voice, video and data communications are still years away, although AT&T and AST SpaceMobile demonstrated voice and video calls via space in 2023.

The FCC’s Regulatory Framework

The Federal Communications Commission (FCC) is also playing a role in evolving satellite-to-cellular communications. In March, FCC commissioners unanimously approved a new regulatory framework called Supplemental Coverage from Space (SCS). It refers to the use of satellite connectivity to supplement and expand terrestrial networks. This first-of-its-kind framework allows cellular network providers and satellite operators to collaborate to expand wireless coverage.

The framework also includes interim requirements for routing 911 calls and texts to public safety answering points. The FCC said satellite-to-cellular connectivity can be a life-saving service for people in remote locations.

In the future, the agency plans to allocate space within certain frequency bands for satellite-to-cellular service. This would enable a single, unified network that isn’t reliant on specific lease agreements between wireless and satellite operators.

Looking Ahead

A practical satellite-to-cellular service would all but eliminate any “dead zones.” Although cellular coverage continues to expand rapidly, many remote areas still lack a sufficient number of cell towers to provide reliable network services. A satellite covers a much larger area than a cell tower, and the growing constellation of satellites can reach all but the most remote places on Earth.

Smartphones are already capable of some basic satellite connectivity — that’s why ocean cruise passengers can use their smartphones for distress signaling and other emergency communications. However, the Starlink service broadcasts in the 1900MHz spectrum, enabling any 5G smartphone to connect. Support for existing devices will enable rapid adoption once these services become available.

SageNet is monitoring advances in this technology with an eye toward meeting our customers’ communications and connectivity needs. In the not-so-distant future, we may be able to offer satellite-to-cellular services as part of our comprehensive connectivity options. Watch this space.