Issue link: https://read.uberflip.com/i/1428395
LoRaWAN ® L2 1.0.4 Specification © 2020 LoRa Alliance ® Page 70 of 90 The authors reserve the right to change specifications without notice. 13.4 Beacon Encoding Examples 2114 2115 Example: This is a valid EU868 beacon frame (SF9): 2116 00 00 | 00 00 02 CC | A2 7E | 00 | 01 20 00 | 00 81 03 | DE 55 2117 Octets are transmitted left to right. The first CRC is calculated on [00 00 00 00 02 2118 CC]. The corresponding field values are shown in Table 79: Beacon Info field format, 2119 InfoDesc=3. 2120 2121 2122 Field RFU Param Time CRC InfoDesc Lat Lng CRC Value Hex 00 00 CC020000 7EA2 0 002001 038100 55DE Table 80: Example of beacon CRC calculation (SF9) 2123 2124 2125 The OPTIONAL gateway specific part provides additional information regarding the gateway 2126 sending a beacon and therefore can differ for each gateway. The OPTIONAL part is protected 2127 by a CRC-16 computed on the GwSpecific + RFU fields. The CRC-16 definition SHALL 2128 be the same as for the mandatory part. 2129 2130 Example: This is a valid US915 beacon (SF12): 2131 2132 2133 Field RFU Param Time CRC InfoDesc Lat Lng RFU CRC Value Hex 0000 00 CC020000 7EA2 00 002001 038100 00 D450 Table 81: Example of beacon CRC calculation 2134 2135 2136 2137 Over the air, the octets are sent in the following order: 2138 00 00 00 | 00 00 02 CC | A2 7E | 00 | 01 20 00 | 00 81 03 | 00 | 50 D4 2139 2140 2141 Listening and synchronizing with the network common part is sufficient to operate a stationary 2142 end-device in Class B mode. A mobile end-device MAY also demodulate the gateway-specific 2143 part of the beacon to be able to signal to the Network Server whenever it is moving from one 2144 cell to another. 2145 13.5 Beaconing Precise Timing 2146 A beacon SHALL be sent every 128s starting on January 6, 1980, 00:00:00 UTC (start of the 2147 GPS epoch) plus T BeaconDelay . Therefore, a beacon is sent at B T = k × 128 + T BeaconDelay 2148 ± T Accuracy seconds after the GPS epoch, where k is the smallest integer for which k × 128 > 2149 T and T = number of seconds since January 6, 1980 00:00:00 UTC (start of the GPS time). 2150