What is difference between Implicit header and Explicit header in LoRaWAN, LoRa
This page describes difference between Implicit header and Explicit header in LoRaWAN packet structure.
It is one of the LPWAN technologies used for long range, low power and offers less interference. LoRa packet consists of three elements viz. preamble, header (optional) and payload.
The above is the common LoRa PHY structure as defined in LoRaWAN specifications.
In order to be compliant with LoRaWAN, end device should support following LoRa physical layer
Preamble size: 8 symbols
Sync Word : 0x34 (Public)
Header : Explicit in uplink/downlink
CRC presence : True (Uplink value) and false (Downlink value)
Spreading factor (SF) and BW : As per region and defined by data rate
IQ Polarizaton : Not-inverted (in uplink) and Inverted (in downlink)
The figure depicts explicit header mode used in LoRa physical layer. Here PHY header (PHDR) and header CRC are included. Here PHDR contains payload length (in bytes), Coding rate (CR) and presence of optional CRC for payload. The integrity of payload is protected by CRC for uplink messages.
The figure depicts implicit header mode. It contains neither PHDR nor PHDR_CRC. LoRaWAN beacons use implicit header mode with fixed length for transmission.
LoRaWAN related links
The LoRaWAN Wireless tutorial covers following sub topics:
LoRaWAN Smart Parking LoRaWAN sensor design LoRaWAN smart healthcare system LoRaWAN smart water metering LoRaWAN architecture LoRaWAN Interface Types LoRaWAN roaming types LoRa tutorial LoRa Frequency Bands LoRa protocol stack LoRa MAC layer LoRaWAN classes LoRa features LoRa Transceiver module