In 1945, the science fiction writer Arthur C. Clarke published an article in the U.K. journal Wireless World that laid out the potential of geostationary orbit for satellite communications.

When a satellite orbits the earth at a certain height it appears from the ground to be stationary allowing an aerial to transmit to and receive from the satellite without having to adjust its orientation. The satellite can then act as a radio relay station in space allowing international communications.

The first active communications satellite, Telstar, was launched in 1962 and relayed the first publicly available live transatlantic television broadcast between North America and Europe.
Telstar was launched into a medium earth orbit (well below geostationary) so the large earth station aerials had to track its path with communications lasting for just 30 minutes.

The first geostationary orbit (GEO) satellite to provide commercial services was launched in April 1965. Intelsat1 (also known as “Early Bird”) provided uninterrupted contact between Europe and North America for television, telephone, and fax transmissions.

Until the expansion of the web of optical fibre submarine cables, GEO satellites using earth stations with large dish antennae relayed most international telephone calls between continents.
In 2003, Eutelsat’s eBird GEO satellite provided Internet access for those in remote areas including ships at speeds comparable to that provided by ADSL over telephone lines, the predominant broadband service at the time.

Advances in technology and the use of higher radio frequencies led to higher speeds in later generations of GEO satellite with access to broadband services provided by very small aperture terminals (VSAT). However, the long distances that signals have to travel leads to long delays between sending and receiving signals.

Then came low earth orbit satellites. As the name suggests, these orbit at a much lower height allowing even faster broadband speeds and much lower delay. However, as LEO satellites move across the sky, a constellation of satellites are required for an uninterrupted service with small, electronically steerable antennae following the satellites’ movement.

There are now over 7500 communications satellites orbiting the earth with the majority being LEO. LEO satellite services have the potential to eliminate Internet access dead zones around the world.

Other uses include providing inflight connectivity for aeroplane passengers and providing backhaul connections between mobile operators’ networks and their base stations in remote areas.
Providing connections to the Internet of Things (IoT) including weather monitoring devices is another possibility.

But perhaps the biggest impact on telecommunications services will be so-called direct to device (D2D) applications where the satellite transceiver is built into devices such as conventional mobile phones. Then ubiquitous access to 4G or 5G mobile services will be possible even when out of range of terrestrial base stations.
SpaceX recently launched six D2D satellites with others planned to provide a constellation of 21 D2D satellites.

You can learn more about satellite communications from the PTT online course “Wireless communications“.

UK mobile operators Vodafone and EE have completed the shutdown of their 3G services. Virgin Media/O2 intends to start retiring their 3G service in 2025.

Vodafone, Deutsche Telecom, and Telefonica in Germany switched of 3G in 2021 and 19 other operators In Europe have announced their intention to switch off 3G by 2025.

In most European countries, 2G (GSM) services will remain operational for a while longer though Swisscom terminated their 2G service in 2021. It is expected that all 2G services in the UK will cease by 2033. This deferment is mainly because 2G is still used for machine type communications including telecare devices, payment terminals, vehicle emergency call (eCall) facility, and smart meters.

The switch-off is happening at different paces globally, with some countries having already completed the process. For example, operators in Australia completed their shut down of 2G in 2018.

The retirement of 2G and 3G services will release radio spectrum that can be refarmed for 4G and 5G services. 5G systems are also ten times more energy efficient than 3G allowing operators to contribute to net zero energy use targets.

The predominant mobile generation in the UK and Europe is now 4G with 93% of the UK landmass being covered by at least one 4G mobile service provider and 71% by all providers.

The provision of a 5G service is also expanding. Approaching 80% percent of the European and UK populations were covered by the 5G service of at least one operator in 2023. Of course, if you happen to live in a “not-spot” of a rural area and are using the “wrong” service provider, then your experience may belie the seemingly encouraging national picture.

To gain the maximum benefit from 5G, a so-called “5G standalone” (5G SA) service that does not rely on existing 4G infrastructure is required. But the implementation of 5G SA has been slow. According to a recent report, just ten 5G SAs have launched in Europe compared with 17 in Asia

50% of the German population has access to Vodafone’s 5G SA service while 5G SA services have recently been launched by Vodafone and VMO2 in several UK cities.

PTT offers several online courses covering mobile technologies and services ranging from the Introduction to mobile systems to the Advanced mobile systems course.

Telecommunications is interwoven into the fabric of modern society. We perhaps take it for granted our ability to access online services and communicate electronically with family, friends, and colleagues.
Because of our reliance on telecommunications, any unravelling of the communications webs that serve national and international communities must be avoided. But threats to our ability to communicate take many forms including natural disasters, accidental damage, and malicious actions.

Earlier this year, damage to four subsea cables off the west coast of Africa disrupted internet services across the continent. Cables affected included the West African submarine cable system (WACS). The cause of the disruption is believed to be seismic activity. A year earlier the same cable was damaged with the cause attributed to a subsea landslide.
Just prior to the 2024 WACS disruption, three submarine cables in the Red Sea were damaged, probably by the anchor of a cargo ship sunk by Houthi militants. The Red Sea is a critical telecommunications route, connecting Europe to Africa and Asia via Egypt. The severing of the WACS system at around the same time made finding alternative routes for African traffic more difficult.

In 2023, a gas pipeline and a close-by subsea telecommunications cable stretching between Finland and Estonia were damaged. On the same night, another subsea telecommunications cable connecting Estonia and Sweden had also been damaged.
The cause of these events is clouded by politics and possible subterfuge. At the time a nuclear-powered ship owned by the Russian state was in the area. But to make the situation even murkier a Chinese vessel was tracked accompanying the Russian ship at both locations. Finland has recovered the anchor of the Chinese vessel from near the gas pipeline. Whether the damage to the two cables and pipeline was accidental or malicious may never be ascertained. Both China and Russia deny any involvement.

Because of these threats to International communications, the EU Council has produced a report on the cybersecurity and resilience of Europe’s communications infrastructures and networks. Included in that report is a recommendation that EU member states should investigate the ownership, capacity, resilience, and redundancy of core Internet infrastructure including submarine cables.

PTT’s online courses “Telecommunications systems security” and “Telecommunications infrastructure and administration” discuss how to improve the resilience of the telecommunications systems we all rely on.