A wireless local area network (WLAN) repeater is an electronic device that is used to extend the distance to which radio signals generated within a wireless network can reach. The function of a WLAN repeater consists of regenerating signals so that signal integrity is maintained as it travels away from the original wireless router that allowed access to the network. This is why a WLAN repeater is also sometimes referred to as a range expander or a WLAN optimizer.
Wireless signals, like signals generated within wired networks, lose their strength as they travel away from the radio device that generated them. This causes users located outside of the ideal range of signal strength not to be able to communicate efficiently with the network or to lose communication altogether. As a signal loses strength, it loses integrity; signals might be thought of as data that need to be communicated from one device on the network to another. These signals are a type of language that each device needs to "hear" clearly enough to understand the message and respond accordingly.
Network administrators might use a WLAN repeater whenever there is a loss of signal integrity because of distance. The WLAN repeater receives signals that have been weakened or that would be received in a distorted form by devices past the point at which the repeater is placed. The repeater then optimizes the signals so that they resemble, as close as possible, the original signals sent by the radio device. After the signals have been optimized or regenerated, they are forcefully sent on to their destinations.
The destinations of the signals regenerated by the WLAN repeater can then respond appropriately as though they had received the information directly from the original sending device. A WLAN repeater is often described as a two-way relay station, because the same process takes place to send signals from an out-of-network-range device back to the original router. Destinations send out their replies, which travel on the waves of the network until they begin to lose integrity. They then arrive at the strategically placed WLAN repeater, where they are regenerated, after which they are sent on their way.
Some network communications problems can persist even with the use of a WLAN repeater. If radio devices of different makes or models are mixed on a network, regeneration might not take place, leaving users physically located far away from the original router unable to connect. Repeaters also must receive a signal that is at least strong enough for it to interpret in order to properly regenerate it.