4.2 MAC Header (MHDR field)

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¹ Maximum payload size is detailed in the Chapter 6.

©2016 LoRa™ Alliance Page 14 of 70

The authors reserve the right to change specifications without notice.

LoRaWAN Specification

1. The MAC header specifies the message type (MType) and according to which major version
2. (Major) of the frame format of the LoRaWAN layer specification the frame has been
3. encoded.

4.2.1 Message type (MType bit field)

1. The LoRaWAN distinguishes between six different MAC message types: join request, join
2. accept, unconfirmed data up/down, and confirmed data up/down.

1. 4.2.1.1 Join-request and join-accept messages
2. The join-request and join-accept messages are used by the over-the-air activation procedure
3. described in Chapter 6.2.
4. 4.2.1.2 Data messages
5. Data messages are used to transfer both MAC commands and application data, which can
6. be combined together in a single message. A confirmed-data message has to be
7. acknowledged by the receiver, whereas an unconfirmed-data message does not require
8. an acknowledgment.¹ Proprietary messages can be used to implement non-standard
9. message formats that are not interoperable with standard messages but must only be used
10. among devices that have a common understanding of the proprietary extensions.
11. Message integrity is ensured in different ways for different message types and is described
12. per message type below.

4.2.2 Major version of data message (Major bit field)

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¹ A detailed timing diagram of the acknowledge mechanism is given in Section 18.

©2016 LoRa™ Alliance Page 15 of 70

The authors reserve the right to change specifications without notice.

LoRaWAN Specification