Issue link: https://read.uberflip.com/i/1428395
LoRaWAN ® L2 1.0.4 Specification © 2020 LoRa Alliance ® Page 41 of 90 The authors reserve the right to change specifications without notice. Note: when applying a TxParamSetupReq command, the end-device 1283 must use whichever is the lowest of either the region limitation for EIRP 1284 or the value encoded in MaxEIRP. It must also use whichever is the 1285 lowest of either region limitation of dwell time or value encoded in 1286 UplinkDwellTime. 1287 1288 The TXParamSetupAns command SHALL be added in the FOpts field (if FPort is either 1289 missing or >0) or in the FRMPayload field (if FPort=0) of all uplinks until a Class A downlink 1290 is received by the end-device. This guarantees that, even in the case of an uplink frame loss, 1291 the Network is always aware of the downlink parameters used by the end-device. 1292 When this MAC command is used in a region where it is not required, the end-device SHALL 1293 NOT process it and SHALL NOT transmit an acknowledgment [RP002]. 1294 5.9 End-Device Time Commands (DeviceTimeReq, DeviceTimeAns) 1295 End-devices and Network Servers SHALL implement these commands. This MAC command 1296 has been introduced in LoRaWAN L2 1.0.3 [TS001-1.0.3]. 1297 An end-device MAY use the DeviceTimeReq command to request the current network time 1298 from the Network Server. This allows the end-device to synchronize its internal clock to the 1299 Network's clock. This is specifically useful to speed up the acquisition of the Class B beacon. 1300 The request has no payload. 1301 A Network Server MAY use the DeviceTimeAns command to provide the GPS time to the 1302 end-device. The time provided is the GPS time at the end of the uplink transmission. The 1303 command has a 5-octet payload defined as follows: 1304 1305 1306 Size (octets) 4 1 DeviceTimeAns payload 32-bit unsigned integer: seconds since epoch* 8-bit unsigned integer: fractional-second in 1 256 s increments Table 50: DeviceTimeAns payload format 1307 1308 1309 The time provided by the Network SHALL have a worst-case accuracy of ±100 ms. The 1310 DeviceTimeAns command SHALL be sent as a Class A downlink (i.e., over RX1/RX2 of the 1311 Class A mode). 1312 1313 (*) The GPS epoch (i.e., January 6, 1980 00:00:00 UTC) is used as origin. The seconds field 1314 is the number of seconds elapsed since the origin. This field increases monotonically by 1 1315 every second. To convert this field to UTC time, the leap seconds SHALL be taken into 1316 account. 1317 1318 Example: Friday, 12 February 2016 at 14:24:31 UTC corresponds to 1319 1139322288s since GPS epoch. As of June 2017, the GPS time is 17s 1320 ahead of UTC time. 1321 1322