Performance Evaluation
Throughput
The performance of any wireless LAN is highly subject to
environmental conditions. Numerous factors, such as mate-
rials of construction, reflecting surfaces, obstructions, etc.
will affect the throughput of radio-based communications
such as a wireless LAN link. It is therefore difficult to
quantify the performance of any wireless product.
Nonetheless, you may want to evaluate the throughput per-
formance of your Harmony 802.11a network for purposes of
comparison with other wireless LAN products or to assess
its behavior in different locations.
Various standard networking tools exist that can help you
qualify the performance of your ad-hoc network without
investing in expensive networking utilities.
NetIQ’s QCheck is a simple network testing utility, which
provides a basic throughput test. You can download a free
copy from the NetIQ web site at
http://www.netiq.com/qcheck/.
This utility needs to be installed on each computer that will
be part of the test. Select Local Host in the drop-down
box for Endpoint 1 and enter the IP address of the remote
computer in the Endpoint 2 box. Change the Data Size to
1000 kBytes and run the test several times in a row by
pressing the <Run> button after each test is completed.
QCheck network testing utility
QCheck will report the throughput for each test in Mbps.
Note, however, that the maximum data size QCheck allows
is only 1 MB. This data size limitation does not demon-
strate the significant throughput advantage of the Harmony
802.11a PC Card, as would a larger data size.
Examples of other methods that can be used to evaluate the
throughput difference between the Harmony 802.11a PC
Card and any other wireless LAN technologies include:
•Perform FTP file transfers of files in excess of, for
example, 50 Mbps, and monitor the throughput
reported by the FTP client
•Transfer high-resolution MPEG-2 video files (e.g., 22
Mbps) and compare the video and audio quality on
the media player
Throughput vs. Radio Rate
With all wireless LAN products, the useable throughput you
will experience does not equal the radio rate. Due to the
fixed overhead associated with managing over-the-air data
transmission, all wireless LANs experience actual through-
put of 30 to 50% of the radio rate. Therefore, in order to
increase user throughput, it is necessary to maximize the
radio rate; your Harmony 802.11a PC Cards offer the high-
est radio rate available in a wireless LAN product!
Range
The data rate of 108 Mbps should be obtainable within a
range of approximately 20 feet in a typical open indoor
environment, for example within a conference room. As
the Harmony 802.11a PC Cards are moved to greater dis-
tances or obstructions, such as walls, are introduced, the
radio will automatically start backing off to lower data rates.
Because of this automatic back-off mechanism, the 802.11a
cards will continually maintain the highest data rate possible
at that range.
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