How to: Extend WLAN Range with Repeaters

By Jim Geier

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If you’re having problems getting signal coverage out to all users, you can likely solve the problem by extending range with a repeater. Learn tips on how repeaters operate and how to install them. 

Access points and Wi-Fi routers play a dominant role in providing radio frequency (RF) coverage in wireless LAN deployments. In some situations, however, there may be coverage holes where users need access to the network. A wireless repeater may be a solution for extending the range of an existing access point (or Wi-Fi router) without adding more access points and corresponding cables.

Repeater basics

A repeater simply regenerates radio signals in order to extend the range of a wireless LAN. The repeater doesn’t physically connect by wire to any part of the network. Instead, a repeater receives radio signals (802.11 frames) from an access point, wireless client device, or another repeater and retransmits the frames without changing the frame contents. This makes it possible for a repeater located between an access point and a distant user to act as a relay point for frames traveling back and forth between the user and the access point.

As a result, wireless repeaters are an effective solution to overcome signal impairments, such as RF attenuation. For example, repeaters provide connectivity to remote areas that would not typically have wireless network access. You may have one Wi-Fi router in a home or small office that doesn’t quite cover the entire area where users need connectivity, such as a basement or patio. The placement of a repeater somewhere between the covered and uncovered areas, however, will provide connectivity throughout the entire space. The wireless repeater fills in the coverage holes. 

It’s very difficult to find wireless LAN devices sold with a repeater as its sole function. Linksys, though, currently has what they refer to as the Wireless-G Range Expander (WRE54G), which is specifically a repeater. Some wireless access points and most bridges also have built-in repeater functionality that you can optionally activate. For example, D-Link sells a wireless access point (WG602) that can be configured as a repeater, but it can also be used as an access point or bridge.

A problem with most repeaters (or access points that can be configured as repeaters) is that they aren’t supported across all wireless LAN vendors. The 802.11 standard wasn’t written with repeaters in mind. As a result, the best approach is to implement a repeater using the same vendor as your existing access points.

Implementation tips

As with any equipment, be sure to follow the manufacturer’s installation instructions when setting up a repeater. In addition, consider the following tips:

All in all, wireless repeaters are an excellent way to increase the radio range of an existing wireless LAN, especially if it’s not practical to install an additional access point. A downside of using a wireless repeater, however, is that it will reduce throughput capacity of the wireless LAN by roughly fifty percent. A repeater must receive and retransmit each frame on the same RF channel, which effectively doubles the number of frames that are sent over the wireless LAN. This problem compounds when using multiple repeaters because each repeater will duplicate the number of frames sent. Thus, be sure to plan the use of repeaters sparingly.

Jim Geier provides independent consulting services and training to companies developing and deploying wireless networks for enterprises and municipalities. He is the author of a dozen books on wireless topics.