Networking —

Troubleshooting a Wireless Infrastructure

Wireless networks do not require physical cable to connect computers; rather, they use wireless media. The benefits of such a configuration are clearusers have remote access to files and resources without the need for physical connections. Wireless networking eliminates cable faults and cable breaks. It does, however, introduce its own considerations such as signal interference and security.

Wireless Signal Quality

Because wireless signals travel through the atmosphere, they are subjected to environmental factors that can weaken data signals. Everything from electrical devices, storms, RF interference, and obstacles such as trees can weaken wireless data signals. Just how weakened the signal becomes depends on many factors; however, all of these elements serve to decrease the power of the wireless signal.

If you are troubleshooting a wireless connection that has a particularly weak signal, there are a few infrastructure changes that can be done to help increase the power of a signal.

  • Antenna Perhaps the first and most obvious thing to check is to ensure that the antenna on the wireless access point is positioned for best reception; this will often take a little trial and error to get the placement right. Today's wireless access cards commonly ship with diagnostic software that displays signal strength.

  • Device Placement One of the factors that can degrade wireless signals is RF interference. Because of this, it is important to try and keep wireless devices away from appliances that output RF noise. This includes devices such as microwaves, certain cordless devices using the same frequency, and electrical devices.

  • Network Location Although there might be limited choice, as much as possible, it is important to try to reduce the number of obstructions that the signal must pass through. Every obstacle strips a little more power from the signal. The type of material a signal must pass through also can have a significant impact on the signal integrity.

  • Boost Signal If all else fails, it is possible to purchase devices such as wireless repeaters that can amplify the wireless signal. The device takes the signal and amplifies it so that the signal has greater strength. This will also increase the distance that the client system can be placed from the WAP.

In order to successfully manage the wireless signals, you will need to know the wireless standard that you are using. The standards that are used today specify range distances, RF ranges, and speeds. It might be that the wireless standard is not capable of doing what you need. Table 2 highlights the characteristics of common wireless standards.

Table 2 Comparing Wireless Standards

Standard

Speed

Range

Frequency

Concerns

802.11a

Up to 54Mbps

2575 feet

5GHz

Not compatible with 802.11g or 802.11b

802.11b

Up to 11Mbps

Up to 150 feet

2.4GHz

Might conflict with other devices using the 2.4GHz range

802.11g

Up to 54Mbps

Up to 150 feet

2.4GHz

Might conflict with other devices using the 2.4GHz range

Bluetooth

720Kbps

33 feet

2.4GHz

Might conflict with other devices using the 2.4GHz range

As you can see in Table 2, the speeds are listed with the "Up to" disclaimer. This is because each standard will decrease the data rate if there is interference. 802.11b wireless link offers speeds up to 11Mbps, but it will automatically back down from 11Mbps to 5.5, 2, and 1Mbps when the radio signal is weak or when interference is detected. 802.11g auto sensing rates are 1, 2, 5.5, 6, 9, 12, 18, 24, 36, 48, and 54 Mbps. Finally, 802.11a provides rates up to 54Mbps, but will automatically back down to rates 48, 36, 24, 18, 12, 9, and 6Mbps.