Designing WLANs is a complex task that requires a thorough
understanding of the underlying technology and design principles.
If you are new to WLAN design and deployment, we strongly recommend
that you read a good book on this topic, such as
The Certified Wireless Design
Professional Official Study Guide.
Additionally, consider the following tips and tricks.
Just because your AP's maximum output power can be set to 17 or 20
dBm does not mean that it should be set to this value. You should
consider the fact that most Wi-Fi client devices, such as laptops,
tablets, or desktops with Wi-Fi adapters, have a lower output
power, typically 13 or 15 dBm. As a result, a client might “hear” a
20 dBm AP from a very long distance, but the AP might not “hear”
the client. Additionally, APs with high output power create
unnecessary interference with other APs in dense WLAN environments.
If you design your WLAN for performance rather than coverage, you
will probably want to have a rather dense placement of APs. Here,
stronger does not necessarily mean better. You might consider
lowering the power level so that it matches the power level of
If you design your WLAN for coverage rather than performance, using
high AP output power might be acceptable. However, be sure to read
the AP specifications to find out the actual power level it can
provide. Remember that the maximum allowed power level might be
different for different channels!
Signal level does not tell you the whole story. Consider an 802.11n
AP operating in the 2.4 GHz band with the standard omnidirectional
antenna and the default 17 dBm output power placed on a map with no
obstructions. If you select the Signal Level visualization,
TamoGraph will draw a very large (a few hundred meters) circle
around your AP. Does this mean that the whole area can be
considered to be covered by the AP? Of course not, because, for
example, at the distance of approximately 300 meters the signal
level would be about -90 dBm. Yes, the signal is there; your client
device might even detect the AP and display it on the list of
available networks; but there would be no connectivity. First,
because the AP might not “hear” the client, as explained before.
Second, even marginal connectivity requires the signal-to-noise
ratio of at least 4 dBm. Considering that the typical noise level
in the 2.4 GHz band in urban areas is about -90 dBm, the signal
level must be at least -86 dBm. At that level, the client might be
able to connect, but the throughput would be extremely poor. That
said, the Expected PHY Rate or AP Coverage Areas
visualizations might be much more informative than the Signal
Level visualization. TamoGraph does not draw the signal level
if the difference between it and the noise level is below 4
It is a common practice nowadays to use the 2.4 GHz band for
legacy, low throughput devices and the 5 GHz band for newer, high
throughput 802.11n, 802.11ac, or 802.11ax devices. When you put a
dual-band AP on the floor plan, both the 2.4 GHz and 5 GHz radios
are enabled by default and both are selected on the AP list on the
left panel of the main application window. This means that the
Signal Level or Expected PHY Rate visualizations will
show you cumulative pictures; if more than one radio is included in
the visualization, they will show the values for the strongest AP.
However, you will probably want to estimate coverage and expected
PHY rates for each band individually, because the range of 5 GHz
radios is shorter and because the attenuation level for 5 GHz
signals is higher. To do that, press the Select APs button
on the toolbar and use the checkboxes next to the APs to select and
deselect them individually. You can also group APs by band and then
select or deselect all 5 GHz or 2 GHz APs with a single click. You
might notice that while good coverage is available in the 2.4 GHz
band in the entire area, 5 GHz coverage is not available
Selecting the right antennas for your AP might considerably
increase signal level, decrease interference, and, therefore,
improve performance. If the antennas of your APs are replaceable,
this adds another degree of freedom to your WLAN design. Using
TamoGraph, you can select an antenna from a large collection of
generic and vendor-specific antennas. You can also view antenna
patterns in 3D.
If in doubt, you can create several copies of the same floor using
different AP and antenna models and see which results best suit
your requirements and budget.