Unscheduled Automatic Power Save Delivery

Unscheduled automatic power save delivery overview

Unscheduled automatic power save delivery (U-APSD) is a QoS facility defined in IEEE 802.11e, which extends the battery life of mobile clients.

  • This feature reduces latency in traffic flow over wireless media

  • U-APSD allows multiple downlink packet delivery with a single uplink trigger, eliminating individual packet polling

  • U-APSD is activated automatically when WMM is enabled

Additional information

Additional details on the QoS facility and its benefits:

  • Extended battery life for mobile clients.

  • Reduction in latency of traffic flow over wireless media.

  • No need for client to poll each individual packet at the access point.

Possible sequence for U-APSD operation:

  1. Client device sends a single uplink trigger packet.

  2. AP delivers multiple downlink packets based on the trigger packet.

View unscheduled automatic power save delivery

Show detailed information of a client by MAC address.

View detailed information of a client by MAC address using this command


        Device# show wireless client mac-address 2B:5B:B3:18:56:E9 detail
        Output Policy State : Unknown
        Output Policy Source : Unknown
        WMM Support : Enabled
        U-APSD Support : Enabled
        U-APSD value : 15
        APSD ACs    : BK(T/D), BE, VI(T/D), VO(T/D)
        Power Save : OFF
        Current Rate : 
        
        --------------------------
        BK : Background
        BE : Best Effort
        VI : Video
        VO : Voice.
        
        T: UAPSD Trigger Enabled
        D: UAPSD Delivery Enabled
        T/D : UAPSD Trigger and Delivery Enabled