I am curious as to how TWT differentiate ( is better ) than 802.11e WNM Sleep mode. I mean, as I understand TWT allows wake up on a per client basis. A client operating in WNM Sleep mode doesn’t have to listen for the Beacon frames during the Listen interval. The client can specify a longer WNM Sleep Interval during which it wakes up to check for the TIM element. The client can also establish traffic filtering rules with the AP or enable a periodic keep-alive report from the client.
What advantages doe TWT offer over WNM sleep mode
Unfortunately, I don't have the infrastructure to test that now.
But I can tell you from my 10+ years of testing several Power Save standards and firmware variations, that how well it works will likely depend on many factors. How it works in one instance may have no relation how it works elsewhere.
Even different, seemingly un-related and innocuous. admin settings may have serious effects on its effectiveness.
The best performance will likely come from an AP and Client manufacturer's cooperative design and test effort. This is one area that a Wi-Fi certification, if there is one for this option, may not guarantee the quality of it's performance.