Improving the Speed and Range of Your Network

Wireless networks make it easier to use technology throughout your home or small office. However, you may find that your wireless network doesn't perform quite as well as you'd hoped. Performance problems with wireless networks can usually be divided into two categories: speed and range. You can improve the speed and range of your wireless network by avoiding interference, using high-gain antennas, and using special devices designed specifically to boost Wi-Fi range.

Identifying Wi-Fi bottlenecks

Follow these steps to identify Wi-Fi bottlenecks:

1. Check the documentation or labeling for wireless devices to make sure that they are compatible with the 802.11g Wi-Fi standard.

2. Open wireless networking utilities on suspect devices and check the transmission rate (see Figure 1).

In Figure 1, the Tx Rate is 11Mbps, which is the speed of 802.11b network gear. If this device is only compatible with 802.11b, installing it could cause your entire network to slow down to 802.11b speeds.

Figure 1: This device is networking at 802.11b speeds.

3. Disable 802.11b gear when maximum Wi-Fi speed is needed.

Adjusting access point speed settings

Use these steps to adjust the speed settings of your access point:

1. Log in to your access point using a Web browser.

2. Locate the performance controls.

3. Select the Enabled radio button by the 802.11g Only Mode option and click OK or Apply.

Adjusting this setting forces your wireless network to perform at the faster 802.11g speed, but 802.11b gear may be unable to access the network.

Networking faster than the speed of G

Belkin, D-Link, Linksys, Netgear, and most other manufacturers of Wi-Fi gear offer accelerator technology that allows connections even faster than 802.11g gear. However, these accelerator technologies are usually proprietary, which means that to actually use the higher speeds the access point and all Wi-Fi adapters must be of the same brand and have the same accelerator technology.

Follow these steps to allow connections faster than 802.11g:

1. Purchase an access point and wireless adapters that use the same wireless acceleration technology.

2. Log in to the access point's control panel and enable the accelerator technology (refer to Figure 2).

3. Launch the wireless adapter software on the client computer.

It is usually necessary to use the adapter's proprietary software to take advantage of acceleration technology. The Windows wireless connection manager can only manage 802.11a/b/g networks.

4. Make sure that the client software uses the same acceleration settings as the access point.

Positioning the access point for best range

Use these steps when positioning your access point:

1. Choose a location that is central to your wireless clients.

2. Mount the access point high and away from obstructions.

Try to mount the access point away from heavy furniture and other large obstacles. Avoid placing the access points near brick, cement, or plaster walls. Windows, mirrors, and other reflective surfaces can also reduce signal range.

Eliminating Wi-Fi interference

Follow these steps to help eliminate Wi-Fi interference:

1. Do not position the access point near appliances that cause interference on the 2.4 GHz band, such as microwaves and baby monitors.

2. Try to use cordless phones that use the 900 MHz or 5.8 GHz bands.

3. Separate Bluetooth and Wi-Fi gear, if possible. Bluetooth signals can cause minor inference with 802.11b/g gear.

Adding a range extending antenna to your access point

Use the following steps to add a range extending antenna to the access point:

1. Choose a directional or omni-directional antenna.

Directional antennas can be aimed to concentrate the range in a specific direction. Omni-directional antennas increase range in any direction.

2. Connect the antenna to your access point.

3. If you have a directional antenna, point it in the direction where you want to most boost your Wi-Fi range.

Using a high gain antenna with a Wi-Fi adapter

To use a high gain antenna with a Wi-Fi adapter, follow these steps:

1. Obtain an antenna that is compatible with your Wi-Fi adapter.

2. Connect the high gain antenna to the adapter.

3. Position the antenna as high as possible for best reception.

Generally speaking, you can only add a high gain antenna to a Wi-Fi adapter if the adapter has a removable antenna. USB and cardbus adapters usually do not have removable antennas, but PCI card Wi-Fi adapters usually do have removable antennas.

Increasing range with a Wi-Fi repeater

Follow these steps to use a Wi-Fi repeater to increase the range:

1. Obtain a Wi-Fi repeater or range extender.

2. Use an Ethernet cable to connect the repeater to your router/access point, or directly to a computer.

3. Log in to the repeater's control panel using a Web browser, just as you would log in to your regular access point.

4. Configure the repeater to use the same SSID and encryption settings as your regular access point.

5. After configuration is complete, disconnect the Ethernet cable and position the repeater about halfway between the access point and the most distant computer.

When positioning a repeater, it must be within range of your regular access point.

Extending WLAN Range with Repeaters

Access points, which require interconnecting cabling, generally play a dominate role for providing radio frequency (RF) (define) coverage in most wireless LAN (WLAN) deployments. Wireless repeaters, though, are an alternative way to extend the range of an existing WLAN instead of adding more access points. There are very few stand-alone 802.11 wireless repeaters on the market, but some access points have a built-in repeater mode. Here's the basic information you need to know when using wireless repeaters.
In general, a repeater (define) simply regenerates a network signal in order to extend the range of the existing network infrastructure. A WLAN repeater does not physically connect by wire to any part of the network. Instead, it receives radio signals (802.11 frames) from an access point, end user device, or another repeater and retransmits the frames. This makes it possible for a repeater located in between an access point and distant user to act as a relay 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 (define). For example, repeaters provide connectivity to remote areas that normally would not have wireless network access. You may have one access point 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 between the covered and uncovered areas, however, will provide connectivity throughout the entire space. The wireless repeater fills holes in coverage, enabling seamless roaming.
A recent review of the repeating function of the D-Link DWL-900AP+ access point identifies a range increase of 160%. In the review, the original signal was lost at about 55feet from the router/access point. With the placement of a DWL-900AP+ set to repeater mode at the site of the original signal loss, the signal strength was still around 72% at 140 feet. The repeater provides the extra kick in situations where you need to reach remote users.
Nearly all WLAN repeaters currently available today are actually built-in functions of access points. For example, the Cisco 350 and 1200 allow you to configure the access point to behave as a repeater (and not as an access point). Buffalo Technology, however, does offer a stand alone repeater in their AirStation Pro Series WLA-AWCG. The advantage of the stand alone repeaters is that they are generally less expensive.
One downside of wireless repeaters, though, is that they reduce throughput on the WLAN. A repeater must receive and retransmit each frame on the same RF channel, which effectively doubles the number of frames that are sent. 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.
The configuration of a repeater is relatively straight forward. After switching the access point to repeater mode, you set the service set identifier (SSID) (define) of the repeater to match the SSID of the specific (root) access points that the repeater will associate with. Most repeaters will, similar to wireless network cards, automatically associate with the access point with the strongest signal. However, you can designate specific MAC addresses of the preferred and secondary access points as an option. If the repeater cannot connect with the preferred access point, it will try to associate with the next one, and so on.
All in all, wireless repeaters are an excellent way to increase the radio range of an existing WLAN, especially if it's not practical to install an additional access point to fully cover the location. Just don't get carried away with installing too many repeaters to keep performance up and users smiling.