SpaceX Sends & Receives Texts Using LTE Enabled Starlink Satellites

SpaceX Sends & Receives Texts Using LTE Enabled Starlink Satellites

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With the first week of January coming to an end, SpaceX has made a big announcement when it comes to the telecommunicatons industry. After launching the first direct to cell Starlink satellites to low Earth orbit (LEO) at the start of this year, America’s most popular aerospace company has confirmed that initial network tests were successful. In a working paper posted on its website, SpaceX shares that it has successfully sent and received text messages on phones connected to Starlink satellites. The firm has also provided details about its cellular capabilities that it is developing in partnership with T-Mobile.

SpaceX Shares Details About Starlink’s Direct To Cell Connectivity

According to SpaceX,  the first text messages were sent from unmodified phones using T-Mobile’s network and Starlink satellites. In the firm’s satellite network model, Starlink satellites receive and send data to the user at one end and to SpaceX’s ground stations on the other. The ground stations complete the end user’s link with internet servers, and the Starlink Direct to Cell coverage adds T-Mobile as an additional link between SpaceX’s ground stations and the servers.

SpaceX’s network supports LTE connectivity, and in its working paper, the firm explains that it had to painstakingly modify existing antenna designs to ensure they can beam down LTE signals from space. At the same time, SpaceX also had to make sure that satellite orbits, their location with respect to the Earth and the number of satellites designated for LTE coverage were perfect so that the network was “just at the edge of physics” where LTE is of sufficient quality to ensure no customer complaints.

SpaceX plans to test Starlink LTE satellite text messages further this year. By 2025, the firm aims to have built a low Earth orbit (LEO) satellite internet constellation capable of voice, data and Internet of Things (IoT) support.

SpaceX’s network diagram for the Starlink direct to cell network

To enable sending and receiving test messages on an unmodified phone through a LEO satellite, SpaceX had to solve the problem of sending high power signals from the spacecraft while keeping power management within a small satellite’s envelope. Larger satellites, such as those in geostationary orbits, are significantly bigger than a typical Starlink satellite and can send large volumes of data.

To manage power, SpaceX developed “custom silicon” that appears exclusive to the Starlink direct to cell satellites. It also “developed large 2.7 m x 2.3 m advanced phased arrays that use extremely sensitive radio receivers and high-powered transmitters for communicating with cell phones from space”. Phased array antenna technology is one of the most advanced communications technologies in the world, and it is used across a myriad of applications, such as radars for fighter aircraft.

One of the biggest benefits of the Starlink direct to satellite service is the fact that it is designed to use LTE/4G protocols. This makes the service available on any smartphone with the right modems or radios. To ensure satellite cellular LTE connectivity, SpaceX has also installed an LTE modem on each of its direct to cell satellites.

Along with partnering up with T-Mobile, SpaceX has also brought telecommunications carriers in Canada, Japan, Australia and other countries on board. Customers of these carriers will be able to use Starlink direct to cell in any location where any one of SpaceX’s partners is providing coverage.

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