Private 5G is a 5G mobile network that a company owns or rents for its own use, inside its own factory, port, mine or campus, where only its own machines and staff may connect. It is also called a captive network or a non-public network. It uses the same kinds of parts as a public network, on a much smaller scale.
A private 5G network has radios on the ceilings or poles of the site, RAN software that controls them, and a small packet core of its own. The core usually runs on a server inside the site. So the company's data never has to leave the site. Running the computing where the data is produced, instead of in a distant data centre, is called edge computing. The company also needs radio spectrum. In India, a company usually leases spectrum from an operator, or has an operator build the network for it. The rules also let a company ask the Department of Telecommunications (DoT) for spectrum of its own, but by 2025 DoT had not assigned spectrum directly to any company.
Why not use Wi-Fi? Wi-Fi is cheaper and works well for laptops. But a large industrial site often needs more than Wi-Fi gives. Machines move across large areas and must not lose their connection as they move. Many sensors must report within a fixed, short delay. And the site wants to decide for itself which devices may connect.
Take, for example, a car plant near Chennai with 120 automated guided vehicles. These are driverless carts that carry parts to the assembly line. On the plant's Wi-Fi, a cart sometimes loses its connection for a second as it passes from one access point to the next. The cart then stops for safety, and the line waits. The plant installs private 5G instead, with 40 radio units across the shop floor. Each cart now carries a 5G module and a SIM issued by the plant. When a cart moves between radios, the network hands over its connection without a break. The core on the plant's own server decides which SIMs may connect. Unknown devices cannot join the network.
Every device on such a network is also part of the plant's industrial control system. So the plant connects its private network to OT and IoT security tools, which list every device and watch what each one does.
Private 5G grew with hardware-software disaggregation. Once the core and the RAN became software on ordinary servers, a company could buy a small network for one site. How is it different from a distributed antenna system (DAS)? A DAS improves the public operators' coverage inside a building, for everyone's phones. A private network serves only the company's own devices.