Target Wake Time

Target wake time

Target wakeup time (TWT) is a power-saving mechanism that

  • allows an AP to schedule specific times for devices or stations (STAs) to wake up and communicate

  • enables those devices to remain in a power-saving state for longer periods, and

  • reduces overall network congestion.

Feature history

Table 1. Feature history for target wake time

Feature name

Release information

Feature description

Target wake time

Cisco IOS XE 17.2.1

Target wake time (TWT) allows an AP to manage activity in the Wi-Fi network, in order to minimize medium contention between Stations (STAs), and to reduce the required amount of time that an STA in the power-save mode needs to be awake.

This is achieved by allocating STAs to operate at non-overlapping times, and/or frequencies, and concentrate the frame exchanges in predefined service periods.

Delivery traffic indication map

With 802.11e, the new power-saving mechanism was introduced that helps voice-capable Wi-Fi devices, as voice packets are transmitted at short time intervals, typically 20 ms/sec.

The existing Wi-Fi client power-saving mechanisms have been in use since 802.11b, where the client devices sleep between AP beacons or multiple beacons, waking up only when they have data to transmit (they can transmit at any time, as AP does not sleep).

A Delivery Traffic Indication Map (DTIM) is a bit-map that

  • is contained within beacons

  • indicates an AP has buffered downlink traffic, and

  • specifies which particular clients are awaiting transmission.

If a client has a DTIM bit set, it can retrieve data from the AP by sending a Power-Save Poll (PS-Poll) frame to the AP. This power-save scheme is effective but only allows clients to doze for a small beacon interval. Clients still need to wake up several times per second to read DTIM from the beacon frame of the AP.

Unscheduled automatic power-save delivery (U-APSD) allows a power-save client to sleep at intervals within a beacon period. AP buffers the downlink traffic until the client wakes up and requests its delivery.


Note

By default Target Wake Time (TWT) is disabled on the controller. To enable TWT, run the ap dot11 {24ghz | 5ghz| 6ghz} dot11ax twt-broadcast command.

Optimize power-saving with target wake time

TWT capable STA can either negotiate an individual TWT agreement with TWT-scheduling AP, or it can elect to be part or member of Broadcast TWT agreement existing on the AP. An STA does not need to be aware that a TWT service period can be used to exchange frames with other STAs.

Any frame exchanges that occur during a TWT service period can use any Physical Protocol Data Unit (PPDU) format that is supported by both the AP and STA involved in that TWT agreement. This includes formats such as High Efficiency Multi-User PPDU (HE MU PPDU) and High Efficiency Trigger-Based PPDU (HE TB PPDU).

The TWT agreement types are:

  • Individual TWT: An individual TWT session is established through negotiation between the AP and a single STA. This arrangement provides a dedicated service period for both downlink and uplink communication between the AP and that specific STA. The expected traffic is highly concentrated within the negotiated service period, achieving up to 99% accuracy. Each service period begins at a defined offset from the Target Beacon Transmission Time (TBTT), lasts for the agreed-upon duration, and then repeats at regular intervals.

  • Solicited TWT: In a solicited TWT agreement, the STA initiates the TWT session by sending a request to the AP.

  • Unsolicited TWT : In an unsolicited TWT agreement, the AP initiates the TWT agreement with the STA. The AP sends a TWT response specifying the service period, which the STA then accepts.

  • Broadcast TWT: In a broadcast TWT agreement, a High-Efficiency AP invites the STA to join a broadcast TWT operation, which may involve participating in an existing broadcast service period or a newly established service period.

TWT requesting STA communicates the wake scheduling information to its TWT responding AP, which then devises a schedule and delivers the TWT values to the TWT requesting STA when a TWT agreement has been established between them.

Configure target wake time at radio level (CLI)

Complete this task to configure target wake time at the radio level.

Procedure

Step 1

Enter the global configuration mode.

Example:

Device# configure terminal

Step 2

Disable the 802.11a, 802.11b, or 802.11 6-GHz network.

Example:

Device(config)# ap dot11 {24ghz | 5ghz | 6ghz} shutdown

Step 3

Configure the 802.11ax parameters.

Example:

Device(config)# ap dot11 {24ghz | 5ghz | 6ghz} dot11ax

802.11ax cannot be disabled on the 6-GHz band.

Step 4

Configure 802.11 6-GHz dot11ax target wake-up time.

Example:

Device(config)# [no] ap dot11 {24ghz | 5ghz | 6ghz} dot11ax target-wakeup-time

Step 5

Configure 802.11 6-GHz dot11ax target wake-up time broadcast.

Example:

Device(config)# [no] ap dot11 {24ghz | 5ghz | 6ghz} dot11ax twt-broadcast

Note

 

By default TWT is disabled on the controller. Enable TWT by running this command.

Step 6

Enable the 802.11a, 802.11b, or 802.11 6-GHz network.

Example:

Device(config)# no ap dot11 {24ghz | 5ghz | 6ghz} shutdown

Step 7

Display and verify the 802.11ax network configuration details, which includes information about Target Wakeup Time and Target Wakeup Broadcast.

Example:

Device(config)# show ap dot11 {24ghz | 5ghz | 6ghz} network

The target wakeup time at the radio level is configured.

Device# configure terminal
Device(config)# ap dot11 24ghz shutdown
Device(config)# ap dot11 24ghz dot11ax 
Device(config)# [no] ap dot11 24ghz dot11ax target-wakeup-time
Device(config)# [no] ap dot11 24ghz dot11ax twt-broadcast
Device(config)# no ap dot11 24ghz shutdown

Enable target wakeup time on WLAN (CLI)

Complete this task to enable target wakeup time on the WLAN.

Procedure

Step 1

Enter the global configuration mode.

Example:

Device# configure terminal

Step 2

Enter the WLAN configuration submode.

Example:

Device(config)# wlan wlan-profile-name

The wlan-profile-name is the profile name of the configured WLAN.

Step 3

Disable the WLAN network.

Example:

Device(conf-wlan)# shutdown

Step 4

Configure target wake time mode on WLAN.

Example:

Device(conf-wlan)# dot11ax target-waketime

Step 5

Configure the TWT broadcast support on WLAN.

Example:

Device(conf-wlan)# dot11ax twt-broadcast-support

Step 6

Enable WLAN.

Example:

Device(conf-wlan)# no shutdown

Step 7

Display the details of the configured WLAN, including Target Wakeup Time and Target Wakeup Broadcast Time.

Example:

Device# show wlan {all | id | name | summary}

The target wakeup time is enabled on the WLAN.

Device# configure terminal
Device(config)# wlan wlan-profile-name
Device(conf-wlan)# shutdown
Device(conf-wlan)# dot11ax target-waketime
Device(conf-wlan)# dot11ax twt-broadcast-support
Device(conf-wlan)# no shutdown

Disable target wakeup time on WLAN (CLI)

Complete this task to disable target wakeup time on WLAN.

Procedure

Step 1

Enter the global configuration mode.

Example:

Device# configure terminal

Step 2

Enter the WLAN configuration submode.

Example:

Device(config)# wlan wlan-profile-name

The wlan-profile-name is the profile name of the configured WLAN.

Step 3

Disable the WLAN.

Example:

Device(conf-wlan)# shutdown

Step 4

Disable the target wake time mode on WLAN.

Example:

Device(conf-wlan)# no dot11ax target-waketime

Step 5

Disable the TWT broadcast support on WLAN.

Example:

Device(conf-wlan)# no dot11ax twt-broadcast-support

Step 6

Enable WLAN.

Example:

Device(conf-wlan)# no shutdown

The target wakeup time is disabled on the WLAN.

Device# configure terminal
Device(config)# wlan wlan-profile-name
Device(conf-wlan)# shutdown
Device(conf-wlan)# no dot11ax target-waketime
Device(conf-wlan)# no dot11ax twt-broadcast-support
Device(conf-wlan)# no shutdown

Configure target wake time (GUI)

Complete this task to configure the target wakeup time and the broadcast for target wakeup time.

Procedure

Step 1

Choose Configuration > Radio Configurations > Parameters.

The parameters page is displayed where you can configure global parameters for 5 GHz band and 2.4 GHz band radios.

Step 2

In the 11ax Parameters section, check the Target Wakeup Time check box and the Target Wakeup Time Broadcast check box to configure target wakeup time and broadcast target wakeup time.

The target wakeup time and the target wakeup time broadcast are configured.

Verify target wakeup time

To verify Target Wakeup Time and Target Wakeup Time Broadcast, use this command

Device#show ap dot11 24ghz network
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802.11ax                                : Enabled
Target Wakeup Time                      : Enabled 
Target Wakeup Time Broadcast            : Enabled
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