It depends on which phone you have, such as an LG with Knock, or if you have the screen saver feature enabled. With Knock, you tap the screen twice to wake it. Screen saver feature is like a PC, when you move the mouse (touch the screen) it wakes up.
I have the Ellipsis 8 HD tablet and cant figure out if it can. I can do the
knock on my LG phone which i love. I didnt check for screen saver on the
Unfortunately the Ellipsis doesn't have that capability like the LG phones. To achieve this effect, you would need to enable the screensaver or Daydream. I have the Ellipsis 10, and that's how I achieve the 'Knock' feature.