Issue link: https://read.uberflip.com/i/1428395
LoRaWAN ® L2 1.0.4 Specification © 2020 LoRa Alliance ® Page 59 of 90 The authors reserve the right to change specifications without notice. 11 Class B Downlink Slot Timing 1823 11.1 Definitions 1824 To operate successfully in Class B, end-devices SHALL open reception slots at precise 1825 instants relative to the infrastructure beacon. This section defines the required timing. 1826 The interval between the start of two successive beacons is called the beacon period. The 1827 beacon frame transmission is aligned with the beginning of the BEACON_RESERVED 1828 interval. Each beacon is preceded by a BEACON_GUARD time interval, where no ping slot 1829 can be placed. The length of the BEACON_GUARD time interval corresponds to the time on 1830 air of the longest allowed frame. This is to ensure that a Class B downlink initiated during a 1831 ping slot just before the BEACON_GUARD time interval will always have time to finish without 1832 colliding with the beacon transmission. The usable time interval for a ping slot therefore spans 1833 from the end of the BEACON_RESERVED time interval to the beginning of the next 1834 BEACON_GUARD time interval. 1835 1836 1837 Figure 5: Beacon timing 1838 1839 1840 1841 1842 1843 1844 BEACON_PERIOD 128 s BEACON_RESERVED 2.120 s BEACON_GUARD 3.000 s BEACON_WINDOW 122.880 s Table 58: Beacon timing 1845 1846 1847 1848 The beacon frame time on air is actually much shorter than the BEACON_RESERVED time 1849 interval to allow network management broadcast frames to be appended in the future. 1850