How is the data from an end-device transmitted to a LoRaWAN Network Server (LNS)
The classical communication case is:
- A LoRa end-device emits a packet and opens a short reception window after the emission.
- The gateway uses its LoRa specific hardware to receive the RF packet.
- A program installed on the gateway named “packet forwarder” retrieves the packet and forwards it to the LNS.
- The LNS analyses the packet and stores it.
- If the LNS decides to reply to this packet, it sends the answer back to the packet forwarder.
- The packet forwarder uses the hardware of the gateway to send the frame (during the reception window).
- The end-device receives the packet.
LoRaWAN protocol
The protocol used by the end-device, the gateway and the LNS is the LoRaWAN protocol. You will find a presentation, a technical introduction, and the detailed specification on the official website.
LoRa specific hardware
The LoRa specific hardware differs from one type of gateway to another. It defines the capabilities of the gateways such as the number of channels, the diversity, the sensitivity, maximal conducted output power (especially for the Wirnet™ iFemtocell-evolution). …
| Gateway type | Conducted output power range |
|---|---|
| Wirnet iBTS | 0dBm to +30dBm |
| Wirnet iFemtoCell | 0dBm to +27dBm |
| Wirnet iStation | 0dBm to +27dBm |
| Wirnet iFemtoCell-evolution | 0dBm to +24dBm (see installation recommendations) |
| Wirnet iZeptoCell Ethernet | 5dBm to +27dBm |
FPGA/HAL
LoRa specific hardware of the gateways is driven by an FPGA. Firmware of this FPGA is regularly updated by Semtech to improve its performances, to add new features and to correct bugs. A static library written in C named HAL (Hardware Abstraction Layer) comes alongside each update.
For almost all users, the use of the FPGA and of the HAL is transparent. Kerlinks provides a CPF (see next paragraph) that takes care of the FPGA update and integrates the HAL.
For the other users, the HAL source code can be provided by Kerlink. Please contact the support team.
Kerlink Common Packet Forwarder (CPF)
The CPF is a set of two daemons (working together) used to send the packets received from the end-devices to the LNS and vice-versa, hence its name.
See Common LoRa Packet Forwarder for more informations
It is the main program of a LoRa gateway. It has to be installed and configured to implement a LoRaWAN network.
It implements "GWMP" protocol to transmit packets to LNS.
Kerlink Basic Station Packet Forwarder (BSPF)
The BSPF implements Lora Basics Station principle.
It allows CUPS or LNS connections to various compatible services (AWS, Chirpstack, …)
See LoRa Use Cases and Kerlink Basic Station Packet Forwarder pages for more informations.
Regulation
Each country has different regulation about RF transmission. Since this is the LNS that schedules the LoRa packets and chooses the RF power used by the gateways, make sure that your LNS configuration fits with your country regulation.
LNS does not handle the LBT feature (Listen Before Talk). A few countries (Japan and Korea) require it. This feature is directly activated in the packet forwarder configuration.