Issue link: https://read.uberflip.com/i/1464682
LoRaWAN ® Application Layer Clock Synchronization Specification TS003-2.0.0 ©2022 LoRa Alliance ® Page 7 of 13 The authors reserve the right to change specifications without notice. 3.1 Package Version Commands (PackageVersionReq, 184 PackageVersionAns) 185 186 The PackageVersionReq command has no payload. 187 188 The end-device SHALL answer this command with a PackageVersionAns command with 189 the following payload: 190 191 Size (octets) 1 1 Field PackageIdentifier PackageVersion Table 3: PackageVersionAns 192 PackageIdentifier uniquely identifies the package. 193 194 PackageVersion corresponds to the version of the package specification implemented 195 by the end-device. 196 3.2 Application Time Commands (AppTimeReq, AppTimeAns) 197 198 The AppTimeReq message is transmitted by the end-device to request a clock correction 199 from the Application Server. The message is meant to be transmitted periodically by the 200 end-device. The default periodicity is a function of the accuracy required by the application 201 and the maximum clock drift speed of the end-device. 202 Note: The expected behavior of the clock synchronization application 203 package is to send the AppTimeReq command regularly (once a day, 204 for example). Most of the time the command will not be answered as 205 the end-device clock will be in sync. This command is meant to be sent 206 in an unconfirmed frame. 207 208 This message is designed to be transmitted only once with a given DeviceTime payload, 209 as the network reception time stamp will be used by the Application Server to compute the 210 required clock correction. If the network settings mandate the end-device to transmit the 211 same message multiple times (i.e., NbTrans set to greater than 1), the accuracy of the 212 clock synchronization package will be lowered since there is no way to know which 213 transmission of the same message was used by the Application Server. The clock correction 214 may be calculated based on the first transmission, the last transmission, or any transmission 215 of the same payload in between. The end-device SHOULD take into account the potential 216 inaccuracy of the server answer when using an NbTrans value greater than 1. 217 218 The AppTimeReq command has the following payload: 219 220 Size (octets) 4 1 Field DeviceTime Param Table 4: AppTimeReq 221 Where: 222 Bits 7:5 4 3:0 Param Fields RFU AnsRequired TokenReq Table 5: Param format 223 224