LoRaWAN protocol

Message flow

Joining

Before communicating, Nodes must be associated or activated using either the Over-the-air-activation (OTAA) or Activation by personalization (ABP). OTAA uses the AppKey which is shared between the Node and the Application Server. During joining, the Node and the Application Server exchange inputs to generate

• the network session key (NwkSKey) for MAC command encryption
• the application session key (AppSKey) for application data encryption

ABP uses an NwkSKey and an AppSKey that are already stored on the Node.

Data transfer

Nodes can transmit data either using confirmed-data or unconfirmed-data messages. The former requires an Ack, while the latter doesn’t. To send a confirmed-data request, the Node sends data with Ackreq = 1 and must wait for the duration AckWaitDuration for the Ack. For unconfirmed-data requests, data is sent with Ackreq = 0.

Data flow

Between the Node and the LNPN, the MAC payload data is encrypted using the NwkSKey. This ensures integrity of the network data.

Between the Node and the Application Server, the application payload data is encrypted using the AppSKey. This ensures that application data can’t be read by the LPNP.

Services

• MCPS (MAC Common Part Sublayer): used for data transmission and reception
• MLME (MAC Layer Management Entity): used for managing the LoRaWAN network
• MIB (MAC Information Base): used for storing information and configuration