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318 Part V: The Part of Tens

Move around your house and think about it from the eyes of Superman, using his X-ray vision to see your access point. If you have a bad signal, think about what’s in the way. If the obstacles are permanent, think about using a

HomePlug wireless access point (which we discuss in Chapter 3) to go around the obstacle by putting an access point on either side of the obstacle.

Another way to get around problems with obstacles is to switch technologies. In some instances, 802.11g could provide better throughput and reach than 802.11a when it comes to obstacles. 802.11g operates at a lower frequency, which does better moving through and around things. If you’re in a dense environment with a lot of clutter and you’re using 802.11a, switching to g might provide some relief.

Install Another Antenna

In Chapter 5, we point out that a detachable antenna is a great idea because you might want to add an antenna to achieve a different level of coverage in your home. Different antennas yield different signal footprints. If your AP is located at one end of the house, it’s a waste to put an omnidirectional antenna on that AP because more than half of the signal might prove to be unusable. A directional antenna would better serve your home.

Antennas are inexpensive relative to their benefit and can also more easily help you accommodate signal optimization because you can leave the AP in the same place and just move the antenna around until the signal is the best. Within a home, there’s not a huge distance limitation on how far the antenna can be away from the AP.

For a more technical explanation of how antennas work, check out the technical white paper section on the Linksys site (www.linksys.com/products/ images/antennawhtpaper.pdf), which at the time of this writing, had a good overview of antennas.

Add a Signal Booster

If you have a big house (or a lot of interference), you can add a signal booster, which essentially turns up the volume on your wireless home network transmitter. A stronger signal means that the receiving point gets a higher quality transmission. This increases throughput by reducing retransmissions of data that occurs when the signal strength is weak.

Chapter 18: Ten Ways to Troubleshoot Wireless LAN Performance 319

A signal booster can also improve the range of your access point (although this is much harder to quantify). Today’s 802.11b and g products typically have a range of 100–150 feet indoors mainly because 802.11b/g products operate at a lower frequency. Although 802.11a products reach a shorter distance — up

to 75 feet indoors — these products are getting better, and their distance is improving. A booster might add another 25–50 feet to this, but it won’t take you to the Starbucks and back.

The signal range of the APs on the market today is steadily increasing because manufacturers are creating more efficient transceiver chipsets. We recommend reading the most recent reviews of products because products truly are improving month over month.

Linksys, for instance, sells its WSB24 Wireless Signal Booster (www.linksys.com; $90) that piggybacks onto a Linksys wireless access point (or wireless access point router) to increase the throughput, effective range, and coverage area of a resulting 802.11b network. (See Figure 18-1.)

This is really easy to install. Simply unscrew the antenna from the AP, connect the two linking wires (an SMA-to-TNC connector, if you’re curious), reattach the antennas onto the booster, and then plug the electric cords in.

Signal boosters are mated devices, meaning that they’re engineered for specific products. Vendors have to walk a fine line when boosting signals in light of federal limits on the aggregate signal that can be used in the unlicensed frequencies. For example, the Linksys Wireless Signal Booster is certified by the Federal Communication Commission (FCC) for use with the WAP11 Wireless Access Point and BEFW11S4 Wireless Access Point Router only. Linksys says that using the WSB24 with any other product from either Linksys or another vendor voids the user’s authority to operate the device.

The main reason why companies like Linksys sell their signal boosters for use with only their own products is because of certification issues. The FCC has to approve any radio transmission equipment sold on the market. A lot of testing must be done for a piece of gear to get certified, and the certification testing must be done for the complete system — and the vendors will usually only do this expensive testing with their own gear.

That having been said, as some reviews have pointed out, you can use the WSB24 with any wireless LAN product that operates in the 2.4 GHz band — notably, 802.11b and 802.11g products. You cannot use it with 802.11a or any dual-band 2.4/5 GHz products; its design cannot deal with the higher frequency.

320 Part V: The Part of Tens

Figure 18-1:

The Linksys WSB24 mated to a Linksys wireless access point.

Photo courtesy of Linksys

Add an AP

Adding another AP (or two) can greatly increase your signal coverage, as shown in Figure 18-2. The great thing about wireless is that it’s fairly

portable — you can literally plug it in anywhere. The main issues are getting power to it and getting an Ethernet connection (which carries the data) to it.

Chapter 18: Ten Ways to Troubleshoot Wireless LAN Performance 321

Coverage by one Access Point – Signal fades with distance

Figure 18-2:

 

Three APs

 

provide

 

a much

 

stronger

 

signal than

Coverage by three Access Points – Strong combined signals

a single AP.