What is the "mushroom head" shaped device in the subway station?

If you look up inadvertently in the subway station, you will find that the mushroom head-shaped thing is firmly attached to the ceiling. What is it used for?

These small mushroom heads are actually part of the subway wireless communication system, called indoor ceiling antennas, which cover the indoor mobile communication signals and ensure that the wireless communication equipment in the subway can be used normally. Generally, they appear in communication blind spots such as subway stations and the top floors of high-rise buildings.

Improve indoor signal strength

Indoor environments such as subway stations and parking lots are deep underground, blocked by thick walls, relatively closed, and have a large flow of people. The signal is often poor, and indoor ceiling antennas are needed at this time. Indoor ceiling antennas can transmit mobile communication signals to every corner of the building, enhance indoor mobile signals, and ensure that people can make calls, send and receive messages, and watch videos normally in subway stations.

Reduce indoor line congestion and interference problems

In crowded places, people using the Internet and telephone at the same time and space will cause line blockage and interference, squeeze out the only signal, and there will be network connection failures.Indoor ceiling antennas can share the traffic of base stations and effectively clear communication blockages and mutual interference.

Indoor ceiling antennas have the characteristics of light structure, easy installation, and beautiful appearance, and are widely used in various places.

In fact, indoor ceiling antennas are not only mushroom-shaped, but also rectangular, square, triangular and other shapes. The antenna is installed inside, and the cable is connected to the back. Some have magnetic suction cups at the bottom, which can be directly sucked on the iron structure. The white part we see is just a protective plastic shell.

The mushroom-shaped one is an omnidirectional ceiling antenna that can transmit signals to all directions, and the square one is a wall-mounted plate antenna that can only transmit signals in a specific direction, but it can be transmitted farther. So sometimes we see not only "mushroom-shaped" but also "square" ones in subway stations. The combination of the two ensures smooth communication.