When we’re out and about, text messages (and also voice calls, mobile data etc.) sent and received through our everyday smartphones are all routed through fixed land-based ‘cell tower’ antennas no more than a few km distant, which form what we might term a ‘Terrestrial Network’ (TN). In rural areas, we often lose cellular wireless signal entirely, even within highly technologically advanced economies such as the UK, EU, US etc. We then find that we are unable to send or receive text messages, even emergency messages. In the 1990s, visionary scientists and engineers developed alternative voice and messaging systems, using satellites as their ‘flying’ cell towers. We will discuss an example of such a pioneering network, called Iridium, which has operated successfully from the late 1990s right up to the present day. Today’s scientist and engineer visionaries are now proposing that the same ‘space-based’ capabilities could be added to our everyday smartphones, without needing to purchase a separate satellite-messaging device. This would allow our phone, when necessary, to switch from the land-based TN to the space-based ‘Non-Terrestrial Network’ (NTN). In this presentation we will discuss some of the technical challenges in achieving this ‘Direct-to-Device’ (D2D) satellite messaging feature, and some of the solutions which are being proposed, and even already being tested for real. One of the leading players in this space is Starlink, so buckle up for a wild ride!

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