What is bluetooth le multi advertising?

Question

I couldn't find a clear explanation what is Bluetooth le multi advertising.

For example, in Specification of the Bluetooth System, I see only description of BLE advertising but not multi advertising.

What the difference between BLE advertising and multi advertising?

Thanks

Answer 1

LE Multi advertising refers to a specific offload (non bluetooth specification) feature that has been implemented in the Android releases by Google, starting from the L release. What multi advertising means is, that your Android phone or a device with Android stack, can enable multiple advertisement trains at the same time. For instance, one specific app can set certain advertisement data (example supported services etc.), advertisement parameters and enable advertisement, and so can N number of other apps, on the same device. At the hardware level (or physical layer), these advertisement trains are interleaved between the three advertisement channels (37, 38, 39) and thus your phone behaves as multiple peripheral devices at the same time. All these advertisement trains also have a separate Random private address, so they are seen distinctly by the remote scanner.