TS011-1.0.0 Relay

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LoRaWAN ® Relay Specification TS011-1.0.0 ©2022 LoRa Alliance ® Page 59 of 60 The authors reserve the right to change specifications without notice. APPENDIX 4: NETWORK TIME 1850 SYNCHRONIZATION 1851 1852 An end-device can send the command DeviceTimeReq to receive the network date and 1853 time from the Network Server. The time provided is the network time captured at the end of 1854 the uplink transmission. 1855 1856 When a relay is added in the loop, the Network Server has to perform some calculations to 1857 find the time of emission of the original uplink. 1858 1859 1860 Figure 18: Network time synchronization 1861 1862 The Network Server is able to compute the time on air of the forwarded message from the 1863 relay: 1864 T2 = T3 – TOA (forwarded uplink) 1865 1866 This specification mandates that the delay between the reception of the uplink from the end- 1867 device and its forwarding by the relay is constant, its value is known as 1868 RELAY_FWD_DELAY. 1869 T1 = T2 - RELAY_FWD_DELAY 1870 1871 The Network Server is now able to send a DeviceTimeAns with a good correction value: 1872 T1 = T3 – TOA (forwarded message) - RELAY_FWD_DELAY 1873 1874 1875 1876 1877 1878 ED Relay GTW T0 T1 T2 T3 T4 T5 T6 T7 Uplink Forwarded Uplink

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