Issue link: https://read.uberflip.com/i/1464684
LoRaWAN ® Remote Multicast Setup Specification TS005-2.0.0 ©2022 LoRa Alliance ® Page 15 of 21 The authors reserve the right to change specifications without notice. StartMissed is set to 1 if the end-device received the request SessionTime, 466 referencing a start of the Class C session window in the past, compared to its internal clock. 467 468 Reserved for future errors bits are unassigned bits in this version of the 469 specification. Those bits SHALL be considered as errors if they are set. The transmitter 470 SHALL set them to '0'. 471 472 If all of the Status&McGroupID bits 2 through 7 are set to '0', the TimeToStart field 473 encodes the number of seconds from the McClassCSessionAns uplink to the beginning of 474 the multicast session. This allows the server to check that the end-device is properly 475 synchronized, enabling the end-device to switch to Class C at the proper time. 476 Note 1: This is possible because the network server timestamps the 477 reception time of uplink packets. Refer to the LoRaWAN Backend 478 Interfaces Specification [TS002]. 479 Note 2: Time synchronization drift is application dependent. The 480 requirement to resynchronize the end-device will be defined by the 481 specific application system. 482 483 If the number of seconds from the McClassCSessionAns uplink to the beginning of the 484 multicast session is greater than 16 777 215 seconds (2 24 -1), TimeToStart SHALL be set 485 to 0xFFFFFF by the end-device. This will inform the Application Server that the end-device 486 clock is out of synchronization. 487 4.6 Multicast Class B Session Commands (McClassBSessionReq, 488 McClassBSessionAns) 489 490 These commands are used to set up a temporary Class B session associated with a 491 multicast context. The settings apply to McAddr independently of the unicast Class B 492 settings that are sent in the PingSlotChannelReq LoRaWAN MAC command (defined in 493 LoRaWAN Link Layer Specification [TS001]). 494 495 The following unicast and multicast class combinations are allowed: 496 Multicast Class B Session Unicast Class A Allowed and can have different parameters (unicast Class A takes priority) Unicast Class A+B Allowed and can have different parameters (unicast Class A takes priority, then multicast Class B, then unicast Class B) Unicast Class A+C Not allowed simultaneously 497 "A given class taking priority" means that the end-device tunes its receiver to the channel 498 parameters of the said class even when there is an overlapping reception of another class. 499 500 It is assumed the end-device has successfully performed beacon acquisition before the 501 temporary Class B multicast session starts. The end-device SHOULD have received and 502 accepted beacon frequency in BeaconFreqReq for successful operation in all regions. 503 Note 1: The end-device should be provisioned as a Class B-capable 504 end-device, so the network server sends BeaconFreqReq. 505