Issue link: https://read.uberflip.com/i/1428353
LoRaWAN Application Layer Clock Synchronization v1.0.0 Specification ©2018 LoRa Alliance™ Page 5 of 13 The authors reserve the right to change specifications without notice. 2 Introduction 100 101 This document proposes an application layer messaging package running over LoRaWAN to 102 synchronize the real-time clock of an end-device to the network's GPS clock with second 103 accuracy. Synchronizing the end-device(s) clock is very useful of many applications like: 104 • Get all end-devices of a multicast group switching to classC temporarily and 105 synchronously at the beginning of the slot 106 • Get many sensors to synchronously perform a measurement (get water meter 107 reading of all meters at midnight every day for example) 108 • Enabling end-devices to transmit time-stamped events (the door was opened this 109 morning at 8:00AM) with a unified clock 110 111 This package is useful for end-devices which do not have access to other accurate time 112 source. An end-device using LoRaWAN 1.1 or above SHOULD use DeviceTimeReq MAC 113 command instead of this package. ClassB end-devices have a more efficient way of 114 synchronizing their clock, the classB network beacon. They SHOULD NOT use this package 115 and directly use the beacon time information. End-devices with an accurate external clock 116 source (e.g.: GPS) SHOULD use that clock source instead. 117 118 All messages described in this document are transported as application layer messages. As 119 such, all unicast messages (uplink or downlink) are encrypted by the LoRaWAN MAC layer 120 using the end-device's AppSKey. 121 122 The package uses a dedicated port to separate its traffic from the rest of the applicative 123 traffic. 124