Chapter 18: Ten Ways to Troubleshoot Wireless LAN Performance
Not many standalone repeaters are on the consumer market. However, whatâ€™s
important for our discussion is that repeater capability is finding its way into
the AP firmware from many AP vendors. A wireless AP repeater basically does
double duty â€” itâ€™s an AP as well as a wireless connection back to the main AP
thatâ€™s connected to the Internet connection.
At its most basic level, a repeater simply regenerates a wireless network
signal in order to extend the range of the existing wireless LAN. You set the
two devices to the same channel with the same Service Set Identifier (SSID),
thus effectively broadening the collective footprint of the signal.
If youâ€™re having throughput performance issues because of interference or
reach, putting an access point into repeating mode might help you extend the
reach of your network. One review of the D-Link (www.d-link.com) DWL-
900AP+ saw a 50 percent improvement in reach.
However, itâ€™s not clear that adding a repeater helps actual throughput in all
situations, unfortunately. Some testing labs have cited issues with through-
put at the main AP because of interference from the new repeating AP (which
is broadcasting on the same channel). Others note that the repeater must
receive and retransmit each frame (or burst of data) on the same RF channel,
which effectively doubles the number of frames that are sent. This effectively
cuts throughput in half. Some vendors have dealt with this issue through
software and claim that itâ€™s not an issue.
Itâ€™s hard to make a blanket statement at this juncture about the basic effec-
tiveness of doing an AP in repeater mode, particularly versus the option of
running a high-quality Ethernet cable to a second AP set on a different chan-
nel. If you can do the latter, thatâ€™s preferable.
When using the bridging/repeating functions of AP/bridges, we recommend
that you use the same product at both ends of the bridge to minimize any
issues between vendors. Most companies support this functionality between
their products only.
Check Your Cordless Phone Frequencies
As we define in Part I of the book, the wireless frequencies at 2.4 GHz and 5.2
GHz are unlicensed, which means that you, as the buyer of an AP and opera-
tor of a wireless broadcasting capability, donâ€™t need to get permission from
the FCC to use these frequencies as long as you stay within certain power
and usage limitations as set by federal guidelines. It also means you donâ€™t
have to pay any money to use the airwaves â€” because no license is required,
it doesnâ€™t cost anything.
324 Part V: The Part of Tens
A lot of consumer manufacturers have taken advantage of these free radio
spectra and created various products for these unlicensed frequencies, such
as cordless phones, wireless A/V connection systems, RF remote controls,
wireless cameras, and so on.
A home that has grown up on RadioShack and X10.com gadgets can likely
have a fair amount of radio clutter on these frequencies in the home. This
clutter can cut into your performance. These sources of RF energy occasion-
ally block users and access points from accessing their shared air medium.
As home wireless LAN usage grows, there are more reports of interference
with home X10 networks, which use various wireless transmitters and signal-
ing over electrical lines to communicate among their connected devices. If
you have a home X10 network for your home automation and it starts acting
weird (like the lights go on and off, and you think your house is haunted),
consider your LAN as a potential problem source. A strong wireless LAN in
your house can be fatal to an X10 network.
At some point, youâ€™ve got to get better control over these interferers, and
there arenâ€™t a lot of options. First, you can change channels, like we mention
earlier in this chapter. Cordless phones, for instance, use channels just like
your local area network; you can change them so that they donâ€™t cross paths
(wirelessly speaking) with your data heading towards the Internet.
Second, you can change phones. If you have an 802.11b or g network operat-
ing at home on the 2.4 GHz band, consider one of the newer 5 GHz cordless
phones for your house. (Or vice versa: If you have an 802.11a, 5 GHz network,
get a 2.4 GHz phone). Note: An old-fashioned 900 MHz phone wonâ€™t interfere
You might find that your scratchy cordless phone improves substantially in
quality and that your LAN performance improves, too. Look for other devices
that can move to other frequencies or move to your 802.11 network itself. As
we discuss in Chapter 19, all sorts of devices are coming down the road that
will work over your 802.11 network and not compete with it. Ultimately, you
need to keep the airwaves relatively clear to optimize all your performance
At the end of the day, interference from sources outside your house is proba-
bly your own fault. If your neighbor asks you how your wireless connection
works, lie and tell him or her that it works horribly. You donâ€™t want your
neighbor getting one and sending any stray radio waves toward your net-
work. And do the same about cable modems. You donâ€™t want your neighborâ€™s
traffic slowing you up because itâ€™s a shared connection at the neighborhood
level. Interference is a sign of popularity â€” it means that a lot of other people
have caught on. So keep it your little secret.
More Than Ten Devices Youâ€™ll
Connect to Your Wireless Network
in the Future
In This Chapter
Singing in the shower (and hot tub) with wireless tunes
Looking under the hood (without lifting the hood)
Losing weight with wireless exercise gear
Wearing wirelessly connected apparel
Tracking Junior and Fido
. . . and more!
W e tell you throughout this book to think bigger-picture than just net-
working your home computers. In Chapter 11, we talk about adding
various peripheral devices (such as a printer) to your home network. In
Chapters 12 and 13, we talk extensively about all the gaming gear and
audio/visual equipment that youâ€™d want to hook into your wireless home net-
work. In Chapter 14, you hear about lots of things you can connect today,
ranging from cameras to cars.
Clearly, the boom is on among the consumer goods manufacturers to net-
work-enable everything with chips. You get the convenience (and cool-factor)
of monitoring the health of your gadgets, and vendors want to sell you add-
on services to take advantage of that chip. This transformation is happening
to everything â€” clocks, sewing machines, automobiles, toaster ovens . . .
even shoes. If a device can be added to your wireless home network, value-
added services can be sold to those who want to track their kids, listen to
home-stored music in the car, and know when Fido is in the neighborâ€™s
garbage cans again.
In this chapter, we expose you to some things that you could bring very soon
onto your wireless home network. These arenâ€™t pie-in-the-sky discussions
326 Part V: The Part of Tens
because many of these products already exist. Expect in the upcoming years
that they will infiltrate your home. Like the Borg say on Star Trek, â€śPrepare to
Yup, wireless toys are everywhere now, having traversed their way into the
innermost sanctuary of your home: the bathroom. Not too many homes are
wired for computer and video in the bathroom, and wireless may be the only
way to get signals â€” like a phone â€” to some of these places. Weâ€™ve seen wire-
less-enabled toilets (donâ€™t ask) and all sorts of wireless controls for lighting
in the bathroom to create just the right atmosphere for that bath. Itâ€™s the
wireless enablement of the bathtub itself that gets us excited. Luxury bathing
combined with a home entertainment bathing center into one outfitted bath-
room set is probably the ultimate for a wireless enthusiast.
Jacuzzi (www.jacuzzi.com) is the leader in this foray. Jacuzzi sells the only
wireless waterproof remote control that weâ€™ve seen, but itâ€™s what comes with
the remote control that gets us. Jacuzziâ€™s J-Allure shower comes standard
with a built-in stereo/CD system, complete with four speakers. A digital con-
trol panel offers easy access to the whirlpool operation, underwater lighting,
and temperature read-out. Talk about wired. The unit is also available with an
optional television/VCR monitor. Cable ready, this feature allows you to enjoy
the morning news or your favorite movie. The multi-channel, 9-inch unit is
waterproof and includes a remote control. You can adapt the monitor for
DVD or WebTV. All these features for a mere $12,500 retail price. The problem
is that most homes arenâ€™t wired for audio or video in their bathroom. Thatâ€™s
where your home wireless network comes into play. You can use the same
wireless A/V extension devices used to link your PC and your stereo system
to reach into the bathroom and bring your J-Allure online.
Jacuzziâ€™s Vizion goes even further â€” it offers a whirlpool bath that boasts a
state-of-the-art entertainment center for a mere $18,000 (not including instal-
lation). And for total indulgence, try a home theater in a tub. The La Scala
model showcases a 42-inch, high-definition plasma monitor as well as a
Surround sound system so powerful that it can make even the most subtle
nuances spring to life. Price: black or white â€” $29,000; platinum â€” $31,000.
But youâ€™ll need your wireless home network to get the signals there!
Your car will also join the wireless revolution and in some neat ways. In
Chapter 15, we discuss how cars are sporting Bluetooth interfaces to enable
devices to interact with the carâ€™s entertainment and communications systems.
Chapter 19: More Than Ten Devices . . .
And in Chapter 14, we discuss the range of aftermarket devices that you can
buy now that will provide 802.11-based connectivity between your homeâ€™s wire-
less LAN and your car, whenever itâ€™s in range. (We guess that makes your
garage a really big docking station!)
Because most cars already have a massive computing and entertainment
infrastructure, reaching out and linking that to both the Internet and your
wireless home network is simply a no-brainer.
A wireless connection in the car enables you to talk to your car via your wire-
less network. Now, before you accuse us of having gone loony for talking to
our car, think about whether your lights are still on? Wouldnâ€™t it be great to
check on it from your 40th-floor apartment instead of heading all the way
down to the parking garage? Just grab your 802.11b-enabled PDA, surf to your
carâ€™s own Web server, and check whether you left the lights on (again). Or
perhaps youâ€™re filling out a new insurance form and forgot to check the
mileage on your car. Click over to the dashboard page and see what it says.
You can also, on request, check out its exact location based on Global
Positioning System (GPS) readings. (GPS is a location-finding system that
effectively can tell you where something is, based on its ability to triangulate
signals from three or more satellites that orbit the Earth. GPS can usually spot
its target within 10â€“100 meters of the actual location.) You can, again at your
request, even allow your dealer to check your carâ€™s service status via the
Internet. You can also, say, switch on the lights or the auxiliary heating, call up
numbers in the car telephone or addresses in the navigation system, unlock
and lock the car â€” all from the wireless comfort of your couch (using some of
those neat touchpanel remote controls that we talk about in Chapter 14). Just
grab your wireless Web tablet, surf, and select. Pretty cool. The opportunities
of being able to wirelessly connect to your automobile are truly endless.
Look for the following near-term applications for wirelessly linking your car
to your home:
Vehicle monitoring systems: These devices â€” usually mounted under a
seat, under the hood, or in the trunk â€” monitor the speed, acceleration,
deceleration, and various other driving and engine performance vari-
ables so that you can determine whether your kids are racing down the
street after they nicely drive out of your driveway. When you drive into
your driveway, the information is automatically uploaded to your PC
over your wireless home network.
Devices like the Davis Instruments Corp. DriveRight (www.davisnet.com,
$139) will likely be using 802.11b. Some of the pricier business products
on the market, such as Road Safety Internationalâ€™s SafeForce, already link
to a base station computer using technologies such as 900 MHz spread-
spectrum, RF data transceiver. Going 802.11b simply makes sense.
328 Part V: The Part of Tens
E-commerce: You hear a great new song on your radio. Maybe you didnâ€™t
catch the artist or song title. You push the Buy button on your audio
system, which initiates a secure online transaction, and a legal copy of
the song is purchased and downloaded to the car at the next wireless
hot spot that your car senses. From now on, you can listen to the song
over and over again, just like you would with a CD. When you get home,
you can upload it to your homeâ€™s audio system.
Remote control: Use remote controls for your car to automatically open
minivan doors or turn on the lights before you get in. And a remote car
starter is a treat for anyone who lives in very hot or cold weather (get
that heater going before you leave your home). Fancier remote controls,
like the AutoCommand Deluxe Remote Starter with Keyless Entry &
Alarm from DesignTech International (www.designtech-intl.com,
$200) have a built-in car finder capability as well as a remote headlight
control. AutoCommand can be programmed to automatically start your
vehicle at the same time the next day, at low temperature, or at low bat-
Okay, so these are not necessarily new and donâ€™t require a wireless
home network. Where it can start to involve that wireless home network
backbone is to start linking these remote control systems to your homeâ€™s
other systems so that this becomes part of your whole home experi-
ence. Imagine using that wireless connection to link to your home
automation system, such as those we discuss in Chapter 14. So when
you utter â€śStart the car,â€ť the system will communicate with the car and
get it into the right temperature setting â€” based on the present temper-
ature outside (it gets its readings from its Oregon Systems wireless
weather station (www.oregonscientific.com).
Your Exercise Gear
Parts of exercise regimens are becoming network aware, and wireless plays a
part, too. One of the more interesting applications of the Internet to the world
of exercise comes from Icon Fitness (iFIT; www.ifit.com), which links your
exercise equipment, the Internet, live personal coaches, and a library of audio
and video slide tours to make each day of exercising a brand-new adventure.