Can Satellites Really Directly Connect to Mobile Phones in the Near Future?

As a Twitter personality known for making bold claims, Elon Musk’s visions, from sending a million people to Mars to uploading his own brain to the cloud and conversing with a virtual version of himself, have become widely recognized.

Just a year ago, Musk, alongside T-Mobile’s CEO, Mike Sievert, announced a groundbreaking plan at SpaceX’s Texas Starbase: SpaceX’s second-generation Starlink satellites will be able to directly connect to mobile phones.

Can Satellites Really Directly Connect to Mobile Phones in the Near Future?

Following this announcement, SpaceX will collaborate with T-Mobile, and starting next year, the new Starlink internet satellites will leverage T-Mobile’s 5G network to provide communication services such as broadcasting and text messaging.

As long as users have T-Mobile network services and their phones support 5G, they can connect directly to the Starlink satellites for network access.

SpaceX has stated that even in the absence of conventional network services, as long as you have a clear view of the sky, you can send text messages or multimedia messages.

T-Mobile has confirmed that its existing mobile phones can utilize this satellite network without the need for additional special equipment.

For those in the tech industry, you might recall the buzz last summer about the iPhone 13 series supporting satellite communication. However, the eventual outcome was that the iPhone 13 series deferred satellite communication to a later time. The skepticism stemmed from the fact that satellite phones are not a new technology; in fact, they are a well-established one. The success of satellite communication depends on factors like signal strength, antenna gain, transmit signal power, receiver sensitivity, and more.

Currently, satellite phones require powerful, highly directional antennas that are not easily disrupted. They are typically limited to outdoor use and often come with prominent antennas. Unlike the densely packed 4G/5G base stations found in urban areas, artificial satellites are often thousands of kilometers away from the Earth’s surface, necessitating greater energy to transmit data over such distances, which is difficult for regular mobile phone transmitters to achieve. The network access equipment used by Starlink still resembles the familiar “satellite dish” design from many years ago.

So, why is Elon Musk confidently claiming to offer satellite communication services to T-Mobile users in the United States next year? It’s important to note that MediaTek recently announced a successful test of the world’s first 5G NTN (Non-Terrestrial Network) satellite phone connection, enabling direct internet access via satellite signals. This test, conducted in collaboration with Germany’s Rohde & Schwarz, was based on the 3GPP Rel-17 standard but was carried out in a laboratory environment, so commercial use is still a long way off.

Elon Musk’s assertion of satellite communication for phones is quite different from what most people understand as mobile communication. Traditional mobile communication, in addition to voice calls, primarily involves internet access. Musk’s statement, however, focuses on providing “text message communication services,” including SMS, MMS, and RCS (Rich Communication Services). In other words, SpaceX’s satellite-to-phone connection will only enable sending text messages; internet browsing won’t be possible.

The ability to send satellite text messages without changes to the mobile device itself is mainly due to SpaceX’s second-generation Starlink satellites. Since the receiving end’s antenna can’t change, SpaceX has opted to enhance reception sensitivity, effectively turning the satellites into “listening posts.” According to official information, the second-generation Starlink satellites add a mid-band PCS spectrum antenna with an area of 25 square meters on top of the original Ku and Ka antennas and inter-satellite laser links to enable direct communication with mobile phones on the ground.

Each mid-band PCS spectrum antenna will create a communication cell on the ground with a bandwidth of 2-4 Mbits, allowing phones within the cell to communicate directly via satellite. Clearly, several Mbits of bandwidth are considered a “small pipe,” but it’s sufficient for text messaging, which is the primary focus here. AST SpaceMobile in the United States has previously employed a similar approach, deploying satellites in near-earth orbit with giant phased-array antennas (450 square meters) to transmit and receive high-gain signals in the 4G/5G frequency bands to regular mobile phones.

However, this approach is not without its flaws. Due to signal attenuation and blockage, using a phone to connect directly to a satellite indoors is unlikely. Additionally, perfect elimination of co-frequency interference within the limited frequency bands to ensure coverage is a significant challenge. It’s worth noting that T-Mobile has tens of millions of users in the United States, while SpaceX’s satellites in orbit number only about 2,845. Perhaps Musk’s goal is not to provide service to all of T-Mobile’s users but to expand the coverage of the Starlink network.

The ultimate vision might be to completely eliminate signal dead zones, allowing users to connect to the outside world by simply looking up at the sky, and this could be Musk’s vision. Currently, globally, only about 30% of land areas are covered by 3G/4G/5G mobile communication networks, leaving areas like deserts, remote mountains, oceans, and the poles without coverage. These are the markets that satellite phones are designed for and the markets that companies like Musk’s SpaceX and mobile operators like T-Mobile are eyeing.

While satellite connections are slow, even taking several minutes for a single text message to be sent and received, their significance lies in the ability to overcome signal blind spots, especially in remote areas or during emergencies. So, despite the relatively modest appearance of the satellite phone market, it is an essential need for many industries, including engineering, shipping, and outdoor activities. It’s worth noting that even Apple has shown interest in this field, having applied for 254 satellite-related patents in recent years, surpassing the number of patents related to UWB (Ultra-Wideband) technology.

In reality, whether it’s SpaceX or Apple, offering satellite services to mobile phone users could be a key avenue for generating more revenue. For mobile operators, expanding network coverage as much as possible is also crucial for gaining a larger market share. Perhaps in the not-so-distant future, the dream of using a mobile phone to connect to the internet via satellite from any corner of the Earth will become a reality.