Why does it seem to take longer to connect to a MatchPort-B/G or other external or embedded WiFi device servers when Radio Power Management is enabled?

The WiPort User Guide explains the Radio Power Management feature as follows:

Enable Power Management, page 60  (http://www.lantronix.com/pdf/WiPort_UG.pdf )
"This allows the software to turn off the radio when expecting not to receive or transmit soon. This feature reduces power consumption by up to 170 mA.
Enabling power management increases the response time because the radio needs to start up again. The radio is enabled to synchronize and check for incoming messages (every 100 ms).
Note: This option is not available when the Topology is set to Adhoc."

Power Management is for radio power management only. The host CPU (in this case our EX chip built into the WiBox) does not go to sleep; only the radio chipset goes to sleep and wakes up regularly (determined by the radio firmware) to receive any packets queued at the AP while it was asleep.  

This sleep interval typically is in the order of hundreds of msec. Thus one should not see non-responsive behavior just as a result of power management if the response time required is higher than hundreds of msec.

Conclusion:  The MatchPort is able to save about 170mA by shutting itself off and restarting every 100ms or so.  The added sleep time will make it take longer to respond to connections, but should not affect applications that do not need response times in the order of hundreds of milliseconds.

[Originally Published On: 10/05/2009 04:11 PM]