Hardware manual

Recommended test program 7
Nov 98
Evaluating mobility parameters
Wireless LANs are targeted towards mobile computing platforms such as laptops, Windows CE handheld
PCs, barcode scanners, pen tablets and more. Since these devices are battery powered, a wireless LAN
adapter that uses as little power as possible is critical to maximize operating time without battery change or
recharge. Products with excessive power drain are problematic, as they consume battery power at a rate which
doesn’t allow for a full work day, a minimum requirement for many mobile applications.
Power management
In order to compare various wireless LAN options, it is important to measure the power consumption through
various typical uses. For example, most users do not require constant access to the network so the test should
run some kind of typical tasks such as printing every 15 minutes and sitting idle for the rest. Here are some
example tests:
1. Create a batch file that prints a file on a network printer every 15 minutes. For the rest of the time, the
unit sits idle. Record the amount of time before the unit runs out of power.
2. Logon to the network and let the unit go into suspend/resume mode. Monitor how long the unit still has
power. Compare this test both with and without the wireless LAN adapter. Also confirm that the unit
resumes operation properly.
3. Run a file transfer between the mobile computer and a network drive continually and record the amount of
time before the unit runs out of power. This test will drain the battery quicker than any other test.
For comparative tests, it is crucial to use handheld PCs or laptops with exactly matching hardware
configuration and battery capacities. Deviations as for instance the presence of a CD-ROM drive can make a
big difference in the battery life. Also, many users are completely unaware of the impact of a screen saver on
battery drain. During times of idle, the screen saver can force the computer system to operate at full speed,
even when no productive work is performed; consequently, these software tools should be turned off for the
test.
Proxim’s RangeLAN2 PC Cards and design-in modules support three different advanced power management
features. All of these are important to conserving the battery life of the mobile computer.
1. Doze mode -- In this mode, the adapter powers down to a low level and will wake periodically to see if
there are messages from the network. The performance of the adapter is roughly the same as a fully
“awake” adapter but the power savings is substantial.
2. Sleep mode -- This state is entered when communication is lost with either the Master or the host and a
configurable time period expires. An adapter in sleep mode can neither send nor transmit frames, but is
woken up if an interrupt is sent to the card.
3. Suspend & Resume mode -- In this mode, the mobile computer shuts power off to the PC Card port.
When the unit wakes, the adapter maintains the network connection as long as the server has not logged
the node off the network.