Satellite network achieves first cellular handoff, cutting switch time to milliseconds

Your phone could soon stay connected even when it moves beyond cellular tower coverage, switching seamlessly to satellites instead.

AT&T and AST SpaceMobile have demonstrated what they believe is the industry’s first successful handoff between a ground-based cellular network and a direct-to-device satellite network.

The milestone could help smartphones switch between conventional cell towers and satellites without dropping calls or losing data connections, bringing seamless satellite connectivity closer to commercial use.

The demonstration took place on October 21 at 8:15 a.m. PT near Granite Falls, Washington. It builds on earlier tests in which AST SpaceMobile’s BlueBird satellites supported voice calls, text messages, and video calls using everyday smartphones. The latest test addressed a different challenge: transferring a connection between two networks operating through very different infrastructure.

Bridging two network worlds

Under the arrangement, AT&T provides the terrestrial wireless network, while AST SpaceMobile operates the satellite network designed to connect directly with standard smartphones. Ericsson and Nokia supplied the technologies needed to coordinate the transition between them.

Ericsson provided AT&T with combined radio and core network technology, alongside intelligent network automation. According to the company, this technology is designed to reduce handoff transition times between ground-based and satellite networks from seconds to milliseconds, helping minimize interruptions as phones move between the two types of coverage.

Nokia supplied radio access technology and mobility software for AST SpaceMobile’s satellite network. These technologies support the transfer of connections between terrestrial networks and satellite coverage, helping maintain service continuity as users move between them.

The companies are working to make satellite connectivity function as an extension of existing mobile networks rather than a separate service that users must manually activate. This could allow smartphones to move between available ground-based and space-based coverage without requiring users to change devices or network settings.

The approach is particularly relevant to areas where conventional cellular infrastructure is difficult to establish or maintain. Remote communities, highways and disaster-hit locations could benefit from satellite coverage that complements existing wireless networks.

Moving toward commercial service

For AT&T, the satellite network is intended to extend its existing wireless coverage rather than replace terrestrial infrastructure. The company said the integration could help keep customers, first responders, and essential workers connected in locations where traditional mobile coverage is limited.

The latest demonstration is an important step, but the technology is not yet ready for widespread commercial use. AT&T said the next phase is expected to include beta services under real-world conditions, allowing the companies to further refine network performance before moving toward commercial deployment.

Robert Walters, AT&T’s senior vice president of network, described the successful handoff as a significant milestone, while noting that further testing remains necessary.

AST SpaceMobile is developing its BlueBird satellite constellation to deliver 4Gand 5G cellular broadband directly to standard, unmodified mobile devices. Its satellites use large communication arrays designed to connect with smartphones without requiring specialized satellite handsets.

The companies have not announced a firm commercial launch date for the seamless handoff service. The upcoming beta phase will help determine how reliably the technology performs outside controlled demonstrations and across different coverage conditions.

If successful, the development could make satellite connectivity a more seamless part of everyday mobile networks, allowing users to remain connected even when they move beyond the reach of conventional cell towers.

Source: https://interestingengineering.com/innovation/satellite-cellular-network-handoff-smartphones