IoTLabs: Exploring LoRaWAN

In this lab, you will be designing and prototyping the first IoT services based on a LoRaWAN network.

During this lab, you will benefit from the first experimental platform implementing an end-to-end LoRaWAN solution in Lebanon. The platform consists of the following elements:

• Devices that communicate to one or more gateways via a wireless interface using single hop LoRa and implementing the LoRaWAN protocol. These devices are physically connected to sensors that generate data.
• Gateways or base stations that forward frames between the devices and the network server. Gateways are connected to the network server via IP interfaces.
• A LoRAWAN backend that implements the network server functions and provides frame control and security.
• Applications that enable to visualize and store the sensor data obtained from the devices.

Figure 1. Architecture of the LoRaWAN Platform

In a LoRaWAN network, the devices communicate with a Network Server through the gateway. The backend installed in the platform is based on an open-source LoRaWAN network-server https://www.loraserver.io. A web interface is available for configuring the applications and devices on the platform (http://212.98.XX.XX:8080).

Figure 2. Loraserver web interface

Start by choosing the application named IoTCourse2122 and create a new device. You should provide the following information:

• A unique device name: IoT-GX (where X is your group number)
• The device description
• A unique device EUI on 64 bits: click on the circular arrow to generate a random EUI.
• A unique application key on 128 bits also obtained by random generation.

Make sure to choose lora-profile as a Device-profile in order to enable OTAA join method.

Devices in the LoRaWAN platform are implemented on Arduino boards with Dragino shields. The combined module as well as the basic configuration steps are presented in Exploring LoRa lab.

Start by verifying the installation on your PC of the latest Arduino IDE. Unzip the Arduino LMIC library and copy it to your sketchbook library folder as detailed in https://www.arduino.cc/en/Guide/Libraries. Then, download and open the example sketch example-code-idoe-iot-lab.ino with Arduino IDE.

Now you should configure your device with the same identifiers DEVEUI and APPKEY as in the backend:

// Change this!
// This should also be in little endian format, see below.
static const u1_t PROGMEM DEVEUI[8]= { };
void os_getDevEui (u1_t* buf) { memcpy_P(buf, DEVEUI, 8);}
 
// Change this!
static const u1_t PROGMEM APPKEY[16] = { };
void os_getDevKey (u1_t* buf) {  memcpy_P(buf, APPKEY, 16);}

Let us analyze the radio parameters in the sketch by answering the following questions.

The LMIC library (see documentation) defines a set of events corresponding to the protocol machine state. These events appear in the onEvent() function.

Finally let us look at the message sending on the device.

Now you are ready to compile the sketch and upload it to the LoRaWAN device. Connect the device to a USB port on your PC, choose the board type as presented in Exploring LoRa lab and select the corresponding port. Compile and upload!

Open the serial monitor in the Arduino IDE at 115200 baud and analyse the debug messages.

Getting back to the backend, you can monitor some important information related to your device. Click on the corresponding device activation.

[currently not working] The backend also enables to capture LoRaWAN frames. Click on LORAWAN FRAMES for your device and answer the following questions accordingly.

mqtt-spy is an open source utility intended to help you with monitoring activity on MQTT topics. It has been designed to deal with high volumes of messages, as well as occasional publications. mqtt-spy is a JavaFX application, so it should work on any operating system with an appropriate version of Java 8 installed (if you encounter problems MQTT.fx can be used). A very useful tutorial is available on https://github.com/eclipse/paho.mqtt-spy/wiki. The tool can be directly downloaded from this link.

You can use mqtt-spy to debug the messages received from the LoRaWAN devices. After starting the application, configure a new connection to the MQTT broker by simply adding the IP address of the broker in the Server URI field. Now you can subscribe to any MQTT topic. If you want to receive all messages arriving at the backend, you can use the generic topic #. You can also limit to the topic including the messages of any specific device: application/APPLICATION_ID/device/DEVICE_EUI/rx.

If you need to send data to your device, you should publish an encoded message in the corresponding topic application/APPLICATION_ID/device/DEVICE_EUI/tx as follows:

{
    "confirmed": false,                        // whether the payload must be sent as confirmed data down or not
    "fPort": 10,                              // FPort to use (must be > 0)
    "data": "...."                            // base64 encoded data (plaintext, will be encrypted by LoRa Server)
}

You can also download a python script that automates the data retrieval from the MQTT broker .

Implement and provide technical documentation for each of the following challenges.

I can send data from the device to the application.

I can send data from the application to the device.

I can tune the LoRa radio parameters.

These two commands can be helpful when used after the join event:

LMIC_disableChannel(N);
LMIC_setDrTxpow(DR_SF12,14);

I can use different sensors to send data from the device: PIR, moisture, temperature, light, etc.