Which stack layer defines the Relay, Proxy, Friend, and the Low Power features for mesh nodes?

[Samira]

I was wondering in Bluetooth mesh, which layer defines the Relay, Proxy, Friend, and the Low Power features for nodes? For example, is it done by the application, Link layer, or physical layer?

[tesc]

Hi,

The features are not strictly defined within a single layer, but they each affect the device's capabilities in one or more of the layers of the stack. The relevant stack layers ranges from the bearer layer to the foundation model layer (with the foundation models controlling what features are enabled.)

The GATT Proxy feature enables use of the GATT bearer.

The Friend feature and the Low Power feature combines to provide low power message reception for the Low Power Node. (TX from the Low Power Node uses the standard protocol of sending normal ADV bearer packets.)

The relay feature makes the node retransmit messages over the advertising bearer. (Mostly affects the network / bearer layers.)

For the short story about layers and concepts, see Bluetooth mesh concepts.

For the full specification, see the Mesh Profile Specification from bluetooth.com, where the features are specified.

Regards,
Terje