U-APSD

Automatic Power Save Delivery (APSD) is an extension of the IEEE 802.11e standard. APSD is offered in two variants:

• Unscheduled APSD (U-APSD)
• Scheduled APSD (S-APSD)

The two methods differ, among other things, in the use of the transmission channels. LANCOM access points and wireless routers support U-APSD, on which the WMM Power Save (WMM-PS) method is also based. U-APSD enables significant power savings for WLAN devices. There is a particularly high demand for this function due to the increasing use of WLAN-enabled telephones (Voice over WLAN – VoWLAN).

By activating the U-APSD for a WLAN, the WLAN devices can switch to snooze mode during calls while they wait for the next data packet. VoIP data transmission takes place in a fixed time pattern—the WLAN devices synchronize their active phases with this cycle so that they are ready again in good time before the next packet is received. This significantly reduces power consumption and noticeably increases battery life.