Sometimes a WLAN access point doesn’t quite cover as much space as needed. Learn tips on how to extend the range of an access point without installing another access point.

A common scenario is where someone installs a wireless LAN and finds that RF coverage isn’t quite good enough. For example, a school may install an access point in a wing of classrooms, and students and teachers have trouble maintaining association with the access point from one particular classroom. In this type of situation, you could try moving the access point to better cover the area, but then you may disrupt access from users in other areas. 

Certainly one solution to this problem is to add another access point to the problem area; however, this requires you to purchase another access point and install the cabling. In addition, you might need to form a distribution system that includes an Ethernet switch in order to connect the access points.

Before installing more access points to increase RF coverage, consider the following methods for extending the range of the access point:

• Adjust the transmit power. Access points generally by default have their transmit power set to the highest value. In some cases, though, an administrator may have switched the transmit power to a lower level, possibly to avoid spilling radio waves outside the facility. In order to maximize RF coverage, ensure that the transmit power is set to the highest value. It only takes a couple minutes to do this, and it might solve the coverage problem without any costs.
• Relocate the access point. In many cases where coverage falls short, you can simply move the access point a few feet (or possibly more) and fully cover the area. The only cost involved with this approach is your time, assuming there’s enough slack in the distribution system cabling. Sometimes you might need to run a longer cable from the switch to the access point, which is a good reason why you should leave some extra length on access point cables when installing them.
• Utilize higher gain antennas. The factory-default antennas that come with an access point usually have low gain (around 2dB). If the access point has removable antennas, then replacing the default antennas with higher gain omni-directional or even directional patch antennas boosts range significantly. Most of these higher gain antennas effectively add 6dB to the system, which equates to a four fold increase in signal power. Even though that doesn’t exactly multiple the range by four, it does make a big difference in range. For example, I’ve seen range increase by twenty five percent after simply replacing the antenna with a higher gain omni. For a cost of around ten dollars each, antenna upgrades are extremely cost-effective. Keep in mind that some access points don’t have removable antennas, which of course blocks you from using this approach.
• Consider RF amplifiers. Companies such as RFLinx and Maxim sell RF amplifiers that install between the antenna and the access point. The amplifiers, which cost a few hundred dollars each, add a whopping 20dB of gain to the RF signal. This packs quite a punch, which dramatically extends range. Just be sure to comply with effective isotropic radiated power (EIRP) rules, though, when adding amplification (and antennas). In addition most regulatory agencies, such as the Federal Communications Commission in the U.S., require certification beyond what the access point manufacturer receives when the wireless LAN includes additional components such as amplifiers. 
• Install a repeater. A wireless LAN repeater, from companies such as D-Link and Buffalo, is stand-alone hardware that you place within the area having poor coverage. The repeater, which must be within range of the access point, is set to the same channel as the access point. The repeater listens to the selected channel and retransmits traffic on the same channel.  For example, the repeater may receive a data frame sent by the access point. The repeater then retransmits the data frame. Users within the area of the repeater will then be able to receive the frame. Because repeaters duplicate the traffic that is sent over a common channel, they reduce the overall throughput by fifty percent. This could be a problem if you’re already taxing the capacity of the access point. Also, a repeater requires electrical power, which might be costly to install. Since a repeater doesn’t connect to the distribution system, power-over-Ethernet (PoE) isn’t an option.

Hopefully one of these approaches will help you successfully extend the range of your access point. If not, then you’ll likely need to purchase and install another access point!

Sometimes a WLAN access point doesn’t quite cover as much space as needed. Learn tips on how to extend the range of an access point without installing another access point.

Jim Geier is an independent consultant and founder of Wireless-Nets, Ltd (wireless-nets.com), a consulting firm assisting municipalities, enterprises, hospitals, airports, and equipment providers with the development and deployment of wireless networks.