Wireless Networking – How to Broadcast PC to Smart TV

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I recently discovered my smart TV has the capability do do screen mirroring from my desktop PC. I was wondering how this worked, or what hardware allows my PC to send data to the TV?

Initially I thought it was because they were both wirelessly connected to the same router, but then I literally unplugged both my router AND cable modem from the wall socket and the screen mirroring was still working (I literally could still move my mouse and open applications and it was displayed on the TV).

Finally I went into my device manager on my PC and disabled the wireless adapter and then the TV screen went blank, so I guess that is what is sending the signal to the TV. What is really puzzling me is how is my wireless PC adapter is directly sending a signal to my Smart TV without either device being connected to the router?

Note: I also noted that in the device manager there was a Miracast device, and under that was listed my smart TV.

Best Answer

Screen casting uses what is known as WiFi Direct.

Essentially both devices will connect to their own private WiFi network with one of them acting as a "host" for the other to send video to.

Wi-Fi Direct allows devices to connect directly to each other, without the need for a Wi-Fi access point (AP). It simply requires the push of a button or the entry of a PIN. Wi-Fi Direct allows source and display devices to discover one another and provides the underlying device-to-device connectivity for Miracast. Miracast builds upon Wi-Fi Direct with mechanisms to negotiate video capabilities, setup content protection (if needed), stream content, and maintain the video session.

WiFi Direct specifically avoids your router and, as the name suggests, connects the two devices directly together.

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