Issue link: https://read.uberflip.com/i/1428395
LoRaWAN ® L2 1.0.4 Specification © 2020 LoRa Alliance ® Page 54 of 90 The authors reserve the right to change specifications without notice. 9 Class B Frame Formats 1696 9.1 Uplink Frames 1697 The uplink frames in Class B mode are the same as the Class A uplinks. The ClassB bit 1698 SHALL be set to 1 in an uplink to signal the Network Server that the end-device is Class B- 1699 enabled and is ready to receive scheduled downlink pings. 1700 9.2 Downlink Frames 1701 The FPending bit for Class B downlink frames signals that, in the event of a ping-slot collision 1702 between multiple Class B ping slots, the ping-slot sequence whose FPending bit was set 1703 first will take priority. If the FPending bit has been set for multiple Class B ping-slot 1704 sequences, they will take priority over ping-slot sequences for which FPending has not been 1705 set. Further prioritization can be determined based on whether the downlink ping slot is used 1706 for multicast or unicast frames. 1707 1708 1709 Priority Type of Class B Downlink Highest Multicast with FPending previously set Unicast with FPending previously set Multicast with FPending not previously set Lowest Unicast with FPending not previously set Table 57: FPending Class B prioritization 1710 1711 1712 1713 If there are multiple colliding ping-slot sequences at the same priority level as shown in Table 1714 57, the highest unicast or multicast DevAddr SHALL take priority. 1715 9.3 Downlink Ping Frames 1716 A downlink ping frame uses the same format as a Class A downlink frame but might follow a 1717 different channel frequency or data rate plan. 1718 1719 Frames can be unicast or multicast. Unicast frames are sent to a single end-device, whereas 1720 multicast frames are sent to multiple end-devices. All end-devices of a multicast group SHALL 1721 share the same multicast address and associated encryption keys. A Class B-capable end- 1722 device SHALL support at least one multicast group and an end-device SHALL NOT transmit 1723 using a multicast address. 1724 1725 More precisely, inside a given end-device, a multicast group is defined by the following 1726 parameters called the multicast group context: 1727 1. A 4-octet network address of the multicast group, common to all end-devices of the group. 1728 2. The multicast group sessions keys (different for every multicast group, but all end-devices 1729 of a given multicast group have the same session keys). 1730 3. The multicast group downlink frame counter. 1731 1732