This is how an FTTH network with GPON technology works

To understand how fiber optic technology further optimizes our connectivity, one has to answer the following question: What is GPON? We explain how it works contingent meaning.

In order to provide us with fast Internet at home, telecommunications operators have various technologies to choose from. The most modern one is based on fiber optic cables and is therefore called Fiber-to-the-Home (FTTH). The FTTH variant more common in Europe is the Gigabit Passive Optical Network, or GPON for short. Here's how GPON works.

The evolution of the internet: faster, better, stronger

The internet has revolutionized our lives since the mid-1990s. The demand for faster, more reliable traffic continues to grow. High definition or 4K streaming, teleworking, and video conferencing are some of the popular Internet services that are skyrocketing the demand for data and bandwidth. The exit restrictions and the lockdown during the Covid-19 crisis have shown how important a good, reliable internet connection is in your own four walls. Thanks to fast internet, we can work efficiently from home, maintain our conversation habits and keep in touch with family and friends via video conference. During this time, the data traffic in all networks has increased significantly.

The first telecommunications networks used copper cables as a medium for signal transmission. For many years these networks were used for basic telephony services, mainly for voice calls and telegrams. With the spread of the Internet since the mid-1990s, voice calls have gradually been replaced by data. And because copper cables quickly reached their limits when transmitting data, a new medium was developed: fiber optic technology.

But why can higher speeds and bandwidths be achieved with fiber optics than with copper technology? Copper cables transmit electrons, while fiber optic cables transmit photons. In other words: glass fibers transmit information using light waves that move much faster than electrons. In addition, light signals do not weaken as much as the electrical signals in copper cables, even over long distances.

The first optical networks emerged in the late 1980s. Initially, fiber optics was used for sea or long-haul cables between large cities such as New York and London or London and Paris. Gradually, copper cables in the entire Internet core network, the backbone, were replaced by optical cables.

As the backbones increased their capacity with the help of fiber, the technology gradually became more widespread - first in large companies and public administrations, and eventually in our homes.

GPON - a flow of light

How is a GPON structured?

The Optical Line Terminal (OLT) is the main element of the network and is located in the switching center of the telecommunications operator, the Central Office. A laser in the OLT feeds the photons from the exchange into an optical fiber made of glass and plastic that ends at a passive optical splitter . The splitter divides the signal received from the exchange into numerous signals, which are ultimately forwarded to up to 64 outputs (customers). The number of customers served by a laser depends on the technical parameters of the operator. The operator often reduces the number of outputs to 32.

In addition, the operator can split the signal twice, for example once into eight and then again into four in the further course of the cable. The maximum distance to the exchange can be 20 kilometers. However, the operators usually limit the distance to 16 kilometers in order to be able to offer a good service.

For Andrés Gavira Etzel, senior engineer at the European Investment Bank, the advantage of fiber optics lies in the lower signal attenuation . In other words, unlike copper cables, the signal strength is largely retained over long distances.

“You can think of the two technologies like a river flowing through a small town,” explains the engineer. “With copper, the channel becomes narrower and narrower, making it more and more difficult for the electrons to flow through. With the glass fiber, the channel does not change, and the photons can continue their way largely unhindered to the end point. In addition, the signal from one copper cable changes the signal from a neighboring cable, which further worsens the signal strength. "

Fast internet is available to all households within a radius of 16 kilometers from an exchange. With ADSL technology, on the other hand, the signal becomes weaker and weaker as the distance increases, with the loss of signal already being considerable after three kilometers.

The fiber optic technology is at least ten times more powerful: While copper-based networks achieve transmission rates of up to 100 megabits per second, optical networks can achieve up to one gigabit per second. The differences are often even greater because the transmission rate for copper cables is usually less than 50 megabits per second.