Wireless networks

What is a wireless network?

A wireless network is an infrastructure which makes it possible to connect a computer to e.g. the Internet via radio-waves, instead of a physical cable.

How does a wireless network work?

To use a wireless network you need a wireless network card. There are wireless network cards both for portable and stationary computers. Wireless network cards are different from other network cards because they have an antenna/aerial for communicating with a base station.

The wireless network card communicates with one or more base stations. A base station is connected to the physical network through a network cable and it's task is to transport the signals between the wireless network and the physical network. One base station can communicate with several wireless network cards simultaneously.

The range of a wireless network.

The range of a wireless network depends on several factors:

• The strenght of the signals sent between the base station and the wireless network card.
• The distance of visibility between the wireless network card and the nearest base station.
• Obstacles that may prevent communication.
• The weather.

Since the signals in a wireless network are radio waves, they are vulnerable in the same way as these. This includes obstacles like ceilings and walls. Wooden walls are normally not a problem, but a more compact/massive material, such as concrete will reduce signal strenght.

Rain, sleet and fog might also reduce signal strenght.

Normally the range of an undisturbed signal is somewhere between 150-200 meters outdoors. Indoors the range is normally around 20 meters through ceilings and walls.

Why use a wireless network?

The main reason for using a wireless network is the demand for mobility (while connected to the network). If your network card is able to connect to several base stations, it will choose to communicate with the station that transmits the strongest signal. The transition between base stations is seamless and happens automatically.

A wireless network provides reduced maintenance costs. It is more expensive to maintenance a physical network, cables, access points in the wall and more, because of the advanced technical level of the task. On the other side, base stations are comparatively simple to install and the task can be performed by most users.

Why are not all networks wireless?

There are some disadvantages linked to a wireless network.

First of all, the transfer rate in a wireless network is considerably poor compared to a physical network. A physical network offers tranfer rates in the upper edge beyond 1 Gbit/sec. A wireless network has a upper limit at 54 Mbit/sec. In addition the wireless transfer rate is limited by several other factors. One limiting factor is multiple users on one base station, which will reduce the transfer rate of each user. The disadvantages related to a wireless network makes it inefficient compared to a physical network.

NTNU's wireless network.

The future goal is to cover all of NTNU's campus, both Gløshaugen and Dragvoll, and for the time being most of the area is covered. You might experience problems in some special areas, where the obstacles mentioned in the article may apply. NTNU continuously work to expand this range.

To be able to employ NTNU's wireless network you either need to log on using NTNUs web-based authentication or download and install a VPN-client on your computer.