TECHNOLOGY FEATURE » WiFi TESTING
>> By Lincoln Lavoie,
Senior Engineer, University of
New Hampshire InterOperability Lab
It’s always fun to peruse through the published statistics from
analysts . Most of the trending ones
are expecting, “Twenty-one billion
devices connected by the year
2020,” from Gartner, but one that
really caught my attention was a
statistic from Cisco, “Sixty-three
percent of internet traffic in 2017
was generated by WiFi-connected
clients .” This was the first time
wireless devices surpassed wired
devices in this statistic. It’s clear
that not one market—residential,
business, or Internet of Things
(Io T)—is single handedly driving
this adoption, rather it’s a
Ultimately, this is leading more
users to the perception that WiFi
and the internet are synonyms,
much to the dismay of broadband
service providers around the world .
There is an increasing number of
support calls for service providers to
troubleshoot WiFi connections for
their subscribers, who claim “The
internet is broken, so it must be
your fault mister service provider.”
As a result, WiFi improvements
and reliability are high on service
provider’s wish lists .
WIFI TES TING METHODS
Part of this problem’s solution lies
in testing WiFi devices, especially
home router equipment offered
by service providers to customers .
Lots of traditional testing has
already been applied to WiFi
devices, including measurements
like total radiated power (TRP) and
radiation pattern measurements,
which have been used for device
manufacturers to develop their
antennas and case designs, trying to
maximize the uniformity of power
transmitted connected devices .
Many developers also perform open
air throughput testing, verifying
bandwidth performance for a single
user. However, as the new WiFi
technologies gain adoption and
deployment numbers, this testing
doesn’t provide the required
coverage to adequately predict
how well a device will perform in
the field .
To guide the development of
testing for these new systems,
it’s helpful to break down the
requirements into a few topics:
• Range Testing: where the
system’s (access point and
station) performance is
measured as a function of the
distance (range or attenuation)
between the two devices .
• Interference Testing: where the
system is operated within the
presence of other interfering
signal (i .e . noise) .
• Multi-device Testing: where the
system must be operated with
coordination between additional
• Interoperability Testing:
where the system must work
with devices from many
Range testing tends to be the
With the number of gadgets connected to the internet forever increasing, it is essential to regularly test
first “check mark” on many
service providers’ set of device
performance requirements . Simply
put, WiFi devices should work
“well” over a range of distances .
In reality, this is actually far
more complex . A key tenet for
all testing should be repeatability.
If the test (setup, design, or
implementation) doesn’t allow
a measurement to produce the
same result over multiple runs,
the test’s value is hugely lowered.
For WiFi testing, this tenet really
requires dedicated supportive
infrastructure. Specifically, the
equipment (including isolation
chambers and controlled channels
between the devices being tested)
greatly improves repeatability
for range and throughput testing .
Ideally, the range testing should
approximate the real-world
environment where the system
would be operating .
Two parts of this environment
are the orientation between the
access point and station—the
multipath channel between devices .
One solution for implementing
orientation within the range testing
is to use near field antennas to
“couple” the device into the channel
between devices . This way, the
device can be “orientated” relative
to the antennas for measuring any
impacts on the system performance .
Figure 1 shows an isolation test
chamber equipped with a turntable
and near field antennas for exactly
this purpose. In this example, the
controlled channel is a four stream
multipath fading channel, where
the attenuation of each path can be
individually controlled .
WiFi Testing: Keeping Up with
the efficiency of our WiFi service.