Issue link: https://read.uberflip.com/i/1428383
LoRaWAN 1.0.3 Specification ©2018 LoRa™ Alliance Page 54 of 72 The authors reserve the right to change specifications without notice. (region specific) should be equal to 0. The optional part is protected by a CRC -16 computed 1424 on the GwSpecific+RFU fields. The CRC-16 definition is the same as for the mandatory part. 1425 For example: This is a valid US900 beacon: 1426 Field RFU Time CRC InfoDesc lat long RFU CRC Value Hex 000000 CC020000 7E A2 00 002001 038100 00 D450 Figure 23 : example of beacon CRC calculation (2) 1427 Over the air the bytes are sent in the following order: 1428 00 00 00 | 00 00 02 CC | A2 7E | 00 | 01 20 00 | 00 81 03 |00 | 50 D4 1429 Listening and synchronizing to the network common part is sufficient to operate a stationary 1430 end-device in Class B mode. A mobile end-device MAY also demodulate the gateway specific 1431 part of the beacon to be able to signal to the Network Server whenever he is moving from one 1432 cell to another. 1433 Note: As mentioned before, all gateways participating in the beaconing 1434 process send their beacon simultaneously so that for network common 1435 part there are no visible on-air collisions for a listening end-device even 1436 if the end-device simultaneously receives beacons from several 1437 gateways. Not all gateways are required to participate in the beaconing 1438 process. The participation of a gateway to a given beacon may be 1439 randomized. With respect to the gateway specific part, collision occurs 1440 but an end-device within the proximity of more than one gateway will still 1441 be able to decode the strongest beacon with high probability. 1442 15.3 Beacon GwSpecific field format 1443 The content of the GwSpecific field is as follow: 1444 Size (bytes) 1 6 GwSpecific InfoDesc Info Figure 24 : beacon GwSpecific field format 1445 The information descriptor InfoDesc describes how the information field Info shall be 1446 interpreted. 1447 1448 InfoDesc Meaning 0 GPS coordinate of the gateway first antenna 1 GPS coordinate of the gateway second antenna 2 GPS coordinate of the gateway third antenna 3 NetID+GatewayID 4:127 RFU 128:255 Reserved for custom network specific broadcasts Table 16 : beacon infoDesc index mapping 1449 For a single omnidirectional antenna gateway the InfoDesc value is 0 when broadcasting 1450 GPS coordinates. For a site featuring 3 sectored antennas for example, the first antenna 1451 broadcasts the beacon with InfoDesc equals 0, the second antenna with InfoDesc field 1452 equals 1, etc. 1453