What Actually Brings Your Data?
The invisible infrastructure behind every connection you make
The concept of the internet can sometimes feel very abstract to people in society. Some think it is a virtual cloud floating somewhere in the sky, and some think it is simply a collection of websites. None of them is wrong, because the internet truly does deliver its services invisibly. Nowadays, people can access the internet easily from almost anywhere. But do you know how this connectivity actually reaches society? The answer lies in the Physical Layer.
In my previous article, I introduced the OSI model and its 7 layers ¹. Now we are going to go deeper into the first and most foundational of those layers, the Physical Layer, and explore what it is and what kinds of physical mediums make it work.
Definition
The Physical Layer is the foundation of network communication. Its sole responsibility is to transmit raw data in the form of bits (1s and 0s) from one device to another through a physical medium ². It does not concern itself with what the data means, whether it arrives correctly, or how it is interpreted, because those responsibilities belong to the layers above it. Because of this, the Physical Layer is often associated with the actual physical devices and mediums we can see and touch in the real world.
There are two types of physical connectivity that link devices together, wired and wireless. The key difference between the two is simply how a device connects to the network.
Wired
In a wired connection, a client connects to the internet through a visible, physical connector. There are several types of wired connectivity commonly used today.
Fiber Optic
This is the backbone of the entire internet. Fiber optic cables transmit data as pulses of light through a glass or plastic core, making them capable of carrying data at speeds of up to 100 Gbps and beyond depending on the infrastructure ³. Because light travels with minimal signal loss over long distances, fiber optic is the number one choice for large scale infrastructure such as submarine cables, ISP backbones, and FTTH (Fiber to the Home) deployments. The tradeoff is cost and complexity, as fiber optic is significantly more expensive to deploy and requires specialized equipment and expertise to install and maintain.
Ethernet (UTP)
If you have ever seen a blue or yellow cable plugged into a router at home or a desktop at the office, that is an Ethernet cable, more specifically an Unshielded Twisted Pair (UTP) cable. It is one of the most widely used wired mediums for local area networks. Modern Ethernet standards such as Cat6 and Cat6a support speeds of up to 10 Gbps over distances of up to 100 meters ⁴, making it one of the most practical and affordable options for access network connections in homes, offices, and data centers.
Coaxial Cable
You may not have heard much about this one, and that is understandable. Coaxial cable is an older technology that has been around for decades. It was widely used in Public Switched Telecommunication Networks (PSTN) and early cable television infrastructure. While it has largely been replaced by fiber optic in modern deployments, coaxial cable is still found in some broadband and cable internet installations, particularly in areas where legacy infrastructure has not yet been upgraded.
Wireless
Wireless Fidelity (Wi-Fi)
Wi-Fi allows devices to connect to the internet without any physical cable. It works by transmitting data over radio waves, typically using the 2.4 GHz and 5 GHz frequency bands, from your device to the nearest access point which is then connected to the broader network. The 2.4 GHz band offers wider coverage but lower speeds, while the 5 GHz band delivers faster speeds over shorter distances. The latest standard, Wi-Fi 6 (802.11ax), can theoretically reach speeds of up to 9.6 Gbps in ideal conditions ⁵, making it more than capable of supporting the growing number of connected devices in modern homes and offices.
Mobile Connection
In outdoor environments where a fixed wired or Wi-Fi connection is not available, mobile communication takes over. Mobile networks transmit data from your device through radio signals to the nearest Base Station, which then routes the data through the mobile core network and out to the internet. In more remote areas, satellite communication serves a similar role. With the rollout of 5G, mobile connections now support speeds of up to 10 Gbps in ideal conditions ⁶, making mobile connectivity an increasingly viable alternative to fixed broadband for both individual users and IoT devices operating at scale.
The Future
As global internet consumption grows exponentially, the physical infrastructure behind it must evolve to keep up. One of the most promising emerging technologies in this space is Photonics. Unlike traditional electronics that use electrical signals to process and transmit data, photonic technology uses light to perform these functions directly ⁷. This means significantly higher bandwidth, lower energy consumption, and reduced latency compared to conventional systems. Researchers are actively developing photonic integrated circuits that could one day replace electronic components in data centers and long haul networks, potentially pushing transmission speeds and efficiency far beyond what is possible today. It is still an emerging field, but photonics represents one of the most exciting frontiers in the future of physical layer technology.
References
Verrell. “Everything is Connected, but How?” Available at: https://substack.com/home/post/p-194379287
GeeksforGeeks. “Physical Layer in OSI Model.” Available at: http://geeksforgeeks.org/computer-networks/physical-layer-in-osi-model/
Open Fiber. “Breakthrough in Connectivity: Speeds up to 100 Gbps.” Available at: https://openfiber.it/en/media/news/breakthrough-in-connectivity-speeds-up-to-100-gbps/
TrueCable. “Cat6 vs Cat6a.” Available at: https://www.truecable.com/blogs/cable-academy/cat6-vs-cat6a
Intel. “Wi-Fi 6 Explained.” Available at: https://www.intel.com/content/www/us/en/gaming/resources/wifi-6.html
Ericsson. “5G Overview.” Available at: https://www.ericsson.com/en/5g
Photonics UK. “What is Photonics?” Available at: https://photonicsuk.org/revolutionising-our-world/what-is-photonics