Issue link: https://read.uberflip.com/i/1428341
RP002-1.0.0 LoRaWAN Regional Parameters ©2019 LoRa Alliance ® Page 83 of 88 The authors reserve the right to change specifications without notice. 3 Physical layer 1671 The LoRaWAN uses a physical layer to communicate with other devices. Two physical 1672 layers are currently supported through the LoRa™ and FSK modulations. 1673 3.1 LoRa™ description 1674 3.1.1 LoRa™ packet physical structure 1675 LoRa™ messages use the radio packet explicit header mode in which the LoRa physical 1676 header (PHDR) plus a header CRC (PHDR_CRC) are included. 1 In explicit header mode the 1677 PHDR specifies: the payload length in bytes, the forward error correction rate, and the 1678 presence of an OPTIONAL CRC for the payload. The integrity of the payload is protected by 1679 a CRC for uplink messages. LoRaWAN beacons are transmitted using LoRa™ modulation in 1680 implicit header mode with a fixed length. In implicit header mode neither the PHDR nor 1681 PHDR_CRC are present. 1682 The PHDR, PHDR_CRC and payload CRC fields are inserted by the radio transceiver. 1683 PHY: 1684 Size 8 Symbols 8 Symbols L bytes (from PHDR) 2 Bytes Packet Structure Preamble PHDR PHDR_CRC PHYPayload CRC (uplink only) Figure 3: LoRa PHY structure 1685 3.1.2 LoRa™ settings 1686 In order to be fully compliant with LoRaWAN, an end device SHALL configure the LoRa™ 1687 physical layer as follows: 1688 1689 Parameter Uplink value Downlink value Preamble size 8 symbols SyncWord 0x34 (Public) Header type Explicit CRC presence True False Coding Rate 4/5 Spreading Factor Defined by the Datarate, specified in each region Bandwidth IQ polarization Not-inverted Inverted Table 95 : LoRa physical layer settings 1690 3.2 FSK description 1691 3.2.1 FSK packet physical structure 1692 FSK messages can be built either by the software stack or by the hardware transceiver, 1693 depending on the end-device architecture. 1694 The PHYPayload length field contains the length in bytes of the PHYPayload field. 1695 The CRC field is computed on PHYPayload length and PHYPayload fields, using the CRC- 1696 CCITT algorithm. 1697 PHY: 1698 1 See the LoRa radio transceiver datasheet for a description of LoRa radio packet implicit/explicit modes.