43 ‐ Mesh network

NUNU Protocol

This firmware since v.21.0 incorporates message hopping mesh network functionality called the "NUNU Protocol".

Tip

You can download early beta NUNU Protocol release here.

Which allows to extend the range of infrastructure-less communications via intermediate stations (nodes).

This way of communications can also be described as flooding.

The protocol is based on the Meshtastic principles.

Videos

For a quick explanation of Meshtastic please check out video below:

Video of the NUNU Protocol showing message hopping with 3 radios:

hop.mp4

Video of the NUNU Protocol with 4 radios:

hop2.mp4

Functionalities

NUNU Protocol implements:

• Carrier-Sense Multiple Access with Collision Avoidance
  • the radio will not TX if the line is busy to avoid collisions
  • if the line is busy the radio will wait with TX for the random amount of time, until the line is free
  • of course there might be a case when 2 radios TX at the same time because they didn't hear each other (also known as the hidden node problem).
• CRC codes to determine if packet has been corrupted in transit
  • all messages with incorrect CRC codes are ignored
  • this is a vital part of the protocol as it prevents hopping incorrect packets through the mesh network
• Give and take approach
  • Users can only request that their messages be hopped if they contribute to the network by hopping messages for others
  • controlled via the MsgAck menu option
• Encryption is supported
  • The nodes that receive encrypted packets without having the right encryption key will not understand them, but will still hop them forward
  • This enables communities to share the mesh network and still have ability to have both public and private conversations
• Hopping state which once entered
  • drops all incoming packets
  • prevents user sending new messages

Packet structure

Packet structure:

Size (in bytes)	Name	Description
4	sync word	Sync word for this FW 0x30 0x72 0x57 0x6C
1	header	Packet header
30	payload	Packet payload (can be encrypted)
13	nonce	Packet nonce used for encryption
8	crc	Error detecting code (based on the display hash function)

Header structure:

Size (in bits)	Name	Description
5	type	Header type
3	hop	Hop count (max 7 hops)

Header types:

Value	Name	Description
0	MESSAGE_PACKET	Unencrypted message
1	ENCRYPTED_MESSAGE_PACKET	Encrypted message
2	INVALID_PACKET	Invalid packet, headers greater and equal to this one as treated as invalid packets