User's Manual

Range is highly dependent on the physical environment. In a line-of-sight location, with elevated and calibrated
antennas, range predictions are quite accurate. This is not true in a “typical” office building, where the walls
may be simple drywall (which is almost transparent to microwaves), or could be plaster with metal underneath.
Most sites are somewhere between these two extremes, and consist of a mixture of surfaces. You can’t tell
what is inside a wall by just looking at it, and we can’t tell you exactly what distance you will achieve. Consider
published range information to be typical, average, common or usual. Do not expect it to be exact.
Signal strength drops when a cell phone is used in the area
Range also depends on the electronic environment. If other equipment that could cause interference is nearby,
the range of your transceiver could vary widely, and could change suddenly when the other equipment
activates. This is particularly true for 802.11b installations, which share their frequencies with microwave ovens,
cordless phones, wireless hi-fi speakers, electronics toys and similar devices. Try to keep your system away
from other transmitters, and from other sources of electrical noise, such as large motors, spot welders, and
similar “electronically noisy” devices.
Range is shorter than it should be
Repeat some tests late in the evening, or on a weekend, when there may be less interference. However, some
users leave their networks turned all the time so this test is not foolproof. By all means, try more than one
channel. Your range problem may just be a nearby user whose system uses your present test channel.
Interference from fluorescent lights
If you mount an access point close to fluorescent light fixtures, the lamp glow appears constant, but inside the
lamp tube, ionization appears and disappears 120 times a second. This can modulate or “chop” an incoming
signal and interfere with reception.
When too much range is undesirable
Too much range is not necessarily a good thing. At first it would appear that you would want as much range as
possible, but with the increase in range comes an increase in interference potential, as your unit hears not only
your other units but also manages to hear the systems of other companies up and down the street. If you have
a large installation, you will also wind up with more than one access point using the same channel. If a remote
unit hears two or more access points, this will slow the network
Prevent access to wireless networks from outside the building
Excess transmit range presents a special reverse problem. For example, putting an access point adjacent to a
second floor bay window invites anyone with the right software on the street below to pick up and enjoy all
network transmissions. We discuss some possible solutions to this problem further on.
Problems with Network Connectivity
If you cannot connect to the wireless network, try the following: