Wireless building to building links

What is a wireless link?

It connects separate local area networks (LANs) usually in different buildings. Each link connects in one of two ways: 'point to point' - which connects two LANs, or 'point to multi-point' - which connects one LAN to multiple others. The frequencies wireless links work at can be selected from a number of ranges. Some frequencies require a license to be purchased, but they should suffer less from interference than the unlicensed frequencies.

Why use a wireless link?

Although they have an initial setup cost, a wireless link is relatively cheap to run and so can be cheaper over the mid and long term than a leased line between buildings. Each wireless link is independent of others and leased lines, so they can increase the overall capacity and reliability of connections between LANs. They can also enable separate buildings to share their internet connections increasing the reliability and utilisation of those internet connections.

What is the range of a wireless link?

The range of wireless link depends on a number of factors including characteristics of the equipment, transmission power, frequencies used, physical obstacles, weather conditions, and interference from other transmitters. Typically wireless links span distances from just a few metres up to 10km, but can extend to well over 100km. Physical obstacles can make a very big difference to range, particularly metal and dense vegetation such as trees. As water absorbs radio waves so rain reduces range. Consequently wet trees will strongly reduce range even after rain stops.

How can a wireless link be implemented?

There are broadly two ways to implement a wireless link. In the first a wireless bridge (or more accurately a Wireless LAN to LAN bridge) has one device in each LAN dedicated to exchanging data. These devices do not exchange data directly with wireless clients. In the second a wireless repeater (also called a range extender) re-broadcasts signals from a wireless network. It is not wired to the main network but is known to it. Its effect is to enable wireless clients to connect that could not ordinarily be reached, such as in another building. A wireless distribution system (WDS) is similar to using wireless repeaters.