Issue link: https://read.uberflip.com/i/1428350
LoRaWAN Remote Multicast Setup v1.0.0 Specification ©2018 LoRa Alliance™ Page 12 of 18 The authors reserve the right to change specifications without notice. 4.5 McClassCSessionReq & Ans 334 335 This message is only used to setup a temporary classC multicast session associated with a 336 multicast context. 337 The payload of the message is: 338 339 Field McGroupIDHeader Session Time SessionTimeOut DLFrequ DR Size (bytes) 1 4 1 3 1 Table 15: McClassCSessionReq 340 Where: 341 McGroupIDHeader Fields RFU McGroupID Size (bits) 6bits 2bits Table 16: McClassCSessionReq McGroupIDHeader field 342 343 And where: 344 345 SessionTimeOut Fields RFU TimeOut Size (bits) 4bits 4bits Table 17: McClassCSessionReq SessionTimeOut field 346 347 McGroupID is the identifier of the multicast group being used. 348 349 SessionTime is the start of the Class C window, and is expressed as the time in seconds 350 since 00:00:00, Sunday 6th of January 1980 (start of the GPS epoch) modulo 2^32. Note that 351 this is the same format as the Time field in the beacon frame. 352 353 TimeOut encodes the maximum length in seconds of the multicast session (max time the 354 end-device stays in classC before reverting to class A to save battery) 355 The maximum duration in second is 2 TimeOut (Example: TimeOut=8 means 256 seconds) 356 This is a maximum duration because the end-device's application might decide to revert to 357 class A before the end of the session, this decision is application specific. 358 For example, the multicast session might be used to broadcast a 359 firmware upgrade file. In that case the end-device might end the 360 multicast session has soon as the full file is received without waiting for 361 TimeOut. 362 363 364 DlFrequ: Encodes the frequency used for the multicast. This field is a 24 bits unsigned 365 integer. The actual channel frequency in Hz is 100 x DlFrequ whereby values representing 366 frequencies below 100 MHz are reserved for future use. This allows setting the frequency of 367 a channel anywhere between 100 MHz to 1.67 GHz in 100 Hz steps. 368 This field has the same meaning and coding as LoRaWAN NewChannelReq MAC command 369 'Freq' field. 370 371 DR: index of the data rate used for the multicast. Uses the same look-up table than the one 372 used by the LinkAdrReq MAC command of the LoRaWAN protocol. 373 374