Issue link: https://read.uberflip.com/i/1464683
LoRaWAN ® Fragmented Data Block Transport Specification TS004-2.0.0 ©2022 LoRa Alliance ® Page 16 of 32 The authors reserve the right to change specifications without notice. 3.5 Fragmentation Data Block Received Commands 440 (FragDataBlockReceivedReq, FragDataBlockReceivedAns) 441 442 This command and answer are used by the end-device to signal the fragmentation server 443 that a data block has been completely received. 444 445 This command SHALL be sent only if the AckReception bit was set in the 446 FragSessionSetupReq command used to set up the corresponding fragmentation session. 447 448 The FragDataBlockReceivedReq command contains a single octet payload: 449 450 Size (octets) 1 FragDataBlockReceivedReq Payload Status Table 19: FragDataBlockReceived Where: 451 Bits 7:3 2 1:0 Status Field RFU MICError FragIndex Table 20: FragDataBlockReceivedReq Status format The MICError encodes the status of the MIC check performed on the data block content. 452 • If the MICError bit value is 1, the MIC computed by the end-device and the 453 one provided in the corresponding FragSessionSetupReq command do not 454 match. The data block will not be processed by the end-device. 455 • If the MICError bit value is 0, the MIC check is successful. 456 If the data block is broadcasted to many end-devices using multicast, the delay between the 457 reception of the last fragment that enables reconstruction of the full data block and the 458 transmission of the FragDataBlockReceivedReq command SHALL be randomized to avoid 459 massive uplink collisions. The randomization interval is a function of the maximum number 460 of end-devices belonging to the multicast group targeted in this fragmentation session. The 461 more end-devices, the longer the interval. This interval is set by the BlockAckDelay 462 parameter of the FragSessionSetupReq command. 463 464 The end-device's application is responsible to retransmit the FragDataBlockReceivedReq 465 command in case no answer is received. The number of transmissions to retry is application 466 specific, but the delay between the two retransmissions SHALL follow the same rules as 467 between the last fragment and the transmission of the first FragDataBlockReceivedReq. 468 469 The server SHALL respond with a FragDataBlockReceivedAns message. This command 470 has a single octet payload. 471 472 Size (octets) 1 Field Param Table 21: FragDataBlockReceivedAns 473