Target Wake Time

[leerees]

There doesn't seem to be any mention of this feature on the forums. However, it's a big part of the marketing for "WiFi 6".

I'm curious if anybody has experimented with it, does it play nice with WiFi calling?

Added with the benefit of reduced congestion on your network, it seems a no brainer to enable this on an AX only network.

It's disabled by default. So what's the catch?

 

[thiggins]

TWT is yet another buzzword for marketeers to throw into their brochures to pad them out.

It was not implemented on consumer routers in early days. It may be now, but I doubt you would see a difference in even a busy consumer network.

The target use case is power saving for IoT devices like sensors and switches that are infrequent network users.

 

[leerees]

The target use case is power saving for IoT devices like sensors and switches that are infrequent network users.

This is what interests me, or more specifically mobile phones.

Whilst all modern smart phones can already intelligently switch off WiFi, these power saving techniques always mess up WiFi calling.

 

[gp-se]

I have it enabled on my AX-86u, I haven't had any issues with WiFi calling or devices falling off the network while asleep.

 

[thiggins]

I have it enabled on my AX-86u, I haven't had any issues with WiFi calling or devices falling off the network while asleep.

Could be because TWT is not enabled on your devices.

 

[leerees]

I have it enabled on my AX-86u, I haven't had any issues with WiFi calling or devices falling off the network while asleep.

That's good to know. What about incoming calls, do they still get through despite the phones potentially being asleep?

 

[thiggins]

Smart phones and other mobile devices have long had complex and aggressive power management. Mobile chips are designed so that device sections can be powered down when not needed, almost to the transistor (ok, so I exaggerate). Since in mobile networks, the network is in control, signaling coordination is a given, i.e. the phone won't be asleep when the network talks to it.

In Wi-Fi, STAs are in control. DTIM and Beacon interval have been the STA sleep control mechanisms until now. TWT is the next iteration of that.

If a device is asleep, it will miss a packet sent during that time. TWT and DTIM provide for buffering on the AP side, so that the message will be sent/resent when the device is awake.

Again, I would not worry about this. I think manufacturers on both ends are still trying to figure out when and how to use TWT.

Like other AX features, if you're worried about it or suspect it's causing problems, shut it off (if the AP provides that switch). You won't be missing much with TWT.

 

[gp-se]

That's good to know. What about incoming calls, do they still get through despite the phones potentially being asleep?

Yes, calls/notifications come through without issue

 

[sfx2000]

If a device is asleep, it will miss a packet sent during that time. TWT and DTIM provide for buffering on the AP side, so that the message will be sent/resent when the device is awake.

I would think that TWT has more benefit for IoT than it would be for handsets/tablets...

TWT came over from 802.11ah...

 

[thiggins]

I would think that TWT has more benefit for IoT than it would be for handsets/tablets...

I agree. Have you seen any working implementations in the wild?

 

[sfx2000]

I agree. Have you seen any working implementations in the wild?

Not in 11ax yet, at least nothing that I've personally observed. Doesn't mean they are not there, but most IOT oriented chipsets are still 11n single stream, at least the ones that are currently significant in the market.

In 2Q2022, maybe we'll see more devices out there with newer radios with 11ax support. Espressif's ESP32-C6 does support 11ax in 2.4GHz, but I've only seen the product announcement, not any actual products yet...

ESP's tend to be more common due to the development environment and existing code base - if one can do arduino, one can do ESP-xxxx, it's very similar.

 

[sfx2000]

@thiggins - this thread might be more suitable for the general wireless thread - there's nothing specific here for ASUS...

 

[thiggins]

but most IOT oriented chipsets are still 11n single stream

That's what I'd expect. It'll be awhile before AX gets cheap enough to make it into IoT products. Or someone even bothers to make a single-stream AX chip.