Issue link: https://read.uberflip.com/i/1479525
LoRaWAN® Regional Parameters RP002-1.0.4 ©2022 LoRa Alliance ® Page 93 of 101 The authors reserve the right to change specifications without notice. 4.3.2 LR-FHSS Packet Physical Structure 1895 LR-FHSS uses redundant physical headers on different frequencies to improve the modulation 1896 robustness to in-band interferers. The number (N) of PHY headers is selectable on a packet- 1897 per-packet basis, in the range 1 to 4. 1898 A LR-FHSS packet has the following structure: 1899 1900 Repeated N (1 to 4) times on different frequencies once Size 114 bits with convolutional coding rate ½ on (PHDR + PHRD_CRC), 2bits preamble and interleaving L Bytes (from PHDR) 2 Bytes 4 Bytes 4 Bytes 1 Byte Packet Structure SyncWord PHDR PHDR_CRC PHYPayload CRC Table 107: LR-FHSS packet structure 1901 A LR-FHSS packet time-on-air can be computed using the following table: 1902 PHY Header Payload + CRC Forward Error Correction Conv ½ Conv 1/3 or 2/3 Bits per hop 114 16 info bits (CR=1/3) 32 (CR=2/3) Time-on-air N* 233.472 mSec Ceil((L+3)/2)*102.4 msec (CR=1/3) ceil((L+3)/4)*102.4 msec (2/3) Table 108: LR-FHSS time-on-air 1903 4.3.3 LR-FHSS PHY Layer Settings 1904 In order to be fully compliant with LoRaWAN, an end-device SHALL configure the LR-FHSS 1905 physical header as follows: 1906 1907 Parameter Uplink Value PHY header (SyncWord, PHDR, PHDR_CRC) repetition (N) N=4: NOT USED N=3 when CR1/3 is used by the Payload N=2 when CR2/3 is used by the Payload N=1: NOT USED SyncWord 0x2C0F7995 Payload CRC Enabled Data Rate Specified in each region Coding Rate 1/3 or 2/3 - Defined by the DR, specified in each region Frequency Hopping Grid 25.4 kHz in FCC like regions 3.9 kHz in other regions Defined by the DR, specified in each region Frequency hopping Bandwidth (OCW) 137 kHz, 336 kHz or 1.523 MHz Defined by the DR, specified in each region Channel/hopping sequence Randomly selected for each transmission Table 109: LR-FHSS physical layer settings 1908 1909