Issue link: https://read.uberflip.com/i/1464683
LoRaWAN ® Fragmented Data Block Transport Specification TS004-2.0.0 ©2022 LoRa Alliance ® Page 6 of 32 The authors reserve the right to change specifications without notice. 2 Introduction 151 152 This document proposes an application layer messaging package running over LoRaWAN to 153 send a fragmented block of data to one or many end-devices. 154 155 All messages described in this document are transported as application layer messages. As 156 such, all unicast messages (uplink or downlink) are encrypted by the LoRaWAN MAC layer 157 using the end-device's AppSKey. Downlink multicast messages are encrypted using a 158 multicast group McAppSKey common to all end-devices of the group. The setup of the 159 group is described in the LoRaWAN Remote Multicast Setup Specification [TS005]. 160 161 The data block transported may be a firmware upgrade, but this document is not specific to 162 any firmware upgrade. Any large (from 1 kB to hundreds of kBs) data block may be sent to a 163 (group of) end-devices using this protocol. 164 Note: This protocol is not designed for very small data blocks, such as 165 files under 1 kB, as it requires some setup frames for each end-device 166 before being operational. It can be more efficient to send small data 167 blocks directly to the end-devices. 168 This protocol is also not designed for very large data blocks (above a 169 few hundred kBs) due to constraints on the link layer (duty cycle 170 limitation and long time on-air) and on the end-device (limited storage 171 memory available and limited FEC reconstruction capacity). 172 The Fragmented Data Block Transport package can be used to: 173 • Set up, report, and delete fragmentation transport sessions 174 • Transfer a fragmented block of data to one or many end-devices 175 • Authenticate a data block once reconstructed 176 • Report on the status of a fragmentation session 177 Fragmentation can be used either over multicast or unicast. Several fragmentation sessions 178 MAY be supported simultaneously by an end-device. 179 This package uses a dedicated port to separate its traffic from the rest of the application 180 traffic. Packages are discoverable using LoRaWAN Multi-Package Access Protocol 181 Specification [TS007]. 182