LoRa forwarder

This project provides a proof-of-concept of a LoRa forwarding device. The forwarder will act as a gateway to the end-device and act as an end-device to the upstream gateway. The software only forwards traffic for a single end-device. Only class A and class C end-devices are supported.

For hardware the forwarder uses a Raspberry Pi connected to an iC880A concentrator board and a EFM32 Giant Gecko using a HopeRF RFM95W radio chip. The concentrator board is connected as explained here. The gecko is connected over a USB to Serial Breakout on the PE0 and PE1 pins.

The software has to run on Raspbian Stretch or a comparable distro. The majority of the software consists of several existing projects to which minor changes are applied. The following external projects are used:

• TheThingsNetwork/lora_gateway
• TheThingsNetwork/packet_forwarder
• brocaar/lora-gateway-bridge
• brocaar/lora-server
• brocaar/lora-app-server
• imec-idlab/LoRaMac-node

Dependencies

Make sure you have the required packages installed:

sudo apt-get install gcc-arm-none-eabi \
                     golang \
                     protobuf-compiler \
                     go-bindata \
                     mosquitto \
                     redis-server \
                     postgresql \
                     npm

pip install paho-mqtt

Setup

Make sure the concentrator board is connected properly (as explained here) and that the antenna is attached.

Make sure SPI is enabled on the Raspberry Pi. You can enable it by running sudo raspi-config, selecting Interface Options and enabling SPI there.

Create a database for the LoRa Server:

make db

Build and install the software to /opt/LoRa-forwarder:

make build
make install

Start the lora-app-server to configure the settings for the end-device. To do this, run sudo systemctl start lora-app-server. You can then connect to https://0.0.0.0:8080. This will print a warning about the certificate because a self-signed certificate was used, discard this warning (in chromium press ADVANCED and then Proceed to 0.0.0.0 (unsafe)). Log in with admin/admin (it might take a while without visible feedback). Click the CREATE APPLICATION button on the page and enter any application name and description in the Application details tab. Under the Network settings tab, you must set the Receive window delay high enough so that the forwarder has time enough to send the packet to the upstream gateway and get a response back. Currently you must set this to 10. After hitting Submit you can press the CREATE NODE button to setup your end-device to your needs.

You will also have to enter the Device EUI of the end-device in the DEVICE_EUI constant on top of /opt/LoRa-forwarder/connect-with-gecko.py. The APPLICATION_ID constant can remain 1 if you didn't create multiple applications. Note that the ApplicationID is not the same as the AppEUI.

The last thing to do is flash LoRaMac-node/LoRaMac-forwarder.hex to the gecko that will be connected to the Raspberry Pi while using the forwarder.

Running

Connect the gecko to the Raspberry Pi or press its reset button when already connected. It will immediately attempt to join the upstream gateway. Once it has done this, it will start listening for serial communication with the Raspberry Pi.

Now run the python script that will communicate with the gecko later when there is a packet to forward to the upstream gateway. Note that this command is blocking.

python /opt/LoRa-forwarder/connect-with-gecko.py

Start the LoRa Server which will handle the connection with the end-device.

sudo systemctl start lora-app-server loraserver lora-gateway-bridge

Finally start the packet forwarder that will configure the concentrator board and pass packets to the LoRa Server. This command is blocking.

cd /opt/LoRa-forwarder/
sudo ./reset-concentrator.sh
./poly_pkt_fwd