How different is a Mesh packet from BLE advertising packet?

[Mitch996]

Hi, I want to confirm if the Mesh packet is a "special" form of advertising packet or it is completely different, i.e. all the headers and addresses etc are changed.

By reading relevant document I get the impression that the 2 are completely different - instead of a packet which is "embedded" inside the payload of an advertising packet, or a packet which alters the fields of an advertising packet to different values but preserved all the formats for an advertising packet.

This means it could be extremely problematic if I want to adopt it to android, which offers very limited capability for me to customize what packet it sends out (with the latest android release that could be a different story).

Any insight?

[bjorn-spockeli]

Hi Mitch,

my interpretation of the Bluetooth Mesh Profile Specification is that is a standard non-connectable and non-scannable undirected advertising packet with the AD type is set to "Mesh Message", see screenshot below.

Not all smartphones will be able to support the Advertisement Bearer(the Mesh Message AD type might not be an option available in the stack), but the Bluetooth Mesh also specifies a GATT bearer, which essentially allows you to tunnel mesh packets through a regular BLE connection.

I recommend that you take a look at the GATT Bearer section and the GATT Proxy Service sections in the Bluetooth Mesh Profile, available here.

Best regards

Bjørn

[bjorn-spockeli]

You do not need to switch roles, the tablet can be the provisioner of the network and send provisioning packets to the proxy node using the GATT bearer, which then relays it to the rest of the mesh using the ADV bearer.

Regardless, the nRF52 should be perfectly capable of provisioning 100 nodes into a network, remember each node is provisioned individually. The limitation will be the number of device addresses, application keys, subnet keys etc it can hold in memory.