Differences

This shows you the differences between two versions of the page.

--- lorawan_downlink [2017/09/04 20:42] – [5. Selecting the Receive Windows] samer
+++ lorawan_downlink [2021/08/28 09:53] (current) – samer
@@ Line 2: / Line 2: @@
 IoT is mostly dominated by the uplink since the typical scenarios consist of sending measurement data from end-devices towards the network. However, in order to take full benefit from the integration of the Internet in the end-devices (this is one basic definition of IoT), downlink can not be neglected. For instance, the network can help in making decisions using the collected data. Then, decisions should to be sent back to the end-devices in order to be implemented: this is where the downlink comes into play.
-===== -. Receive Windows in LoRaWAN =====
+===== - Receive Windows in LoRaWAN =====
 According to the [[https://www.lora-alliance.org/lorawan-for-developers | LoRaWAN specification ]], each uplink transmission by an end-device of class A is followed by two short downlink receive windows as in Figure 1.
@@ Line 11: / Line 11: @@
 [{{ :lorawan-rx-window.png?nolink&400 | Figure 1. LoRaWAN receive windows}}]
-===== -. LoRaWAN End-to-end Platform =====
+===== - LoRaWAN End-to-end Platform =====
 In order to study the downlink in LoRaWAN, we use the platform introduced in [[deploying_lorawan|Deploying an End-to-End LoRaWAN Platform]] and [[esib_iot_challenge|ESIB IoT Challenge]]. This platform shown in Figure 2 represents a typical end-to-end communication chain and includes the following elements:
@@ Line 24: / Line 24: @@
 The backend installed in the platform is based on an open-source LoRaWAN network-server [[https://www.loraserver.io]].
-===== -. Sending Downlink Messages with MQTT =====
+===== - Sending Downlink Messages with MQTT =====
 MQTT is a machine-to-machine (M2M)/"Internet of Things" connectivity protocol. It was designed as an extremely lightweight publish/subscribe messaging transport. The MQTT broker plays an important role in the loraserver backend. It enables to exchange messages between the software components of the backend (gateway bridge, application server, and network server) and also with the application. Therefore, uplink and downlink LoRaWAN messages transit via the MQTT broker.
-==== -. Using mqtt-spy ====
+==== - Using mqtt-spy ====
 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. A very useful tutorial is available on [[https://github.com/eclipse/paho.mqtt-spy/wiki]].
@@ Line 47: / Line 47: @@
 The payload sent by the MQTT client must be encoded in Base64.
 </WRAP>
-==== -. Using IoT MQTT Dashboard ====
+==== - Using IoT MQTT Dashboard ====
 [[https://play.google.com/store/apps/details?id=com.thn.iotmqttdashboard&hl=en | IoT MQTT Dashboard]] is a smartphone application available on Android platforms that enables to manage IoT projects using MQTT protocol. The availability on handheld devices makes this application attractive for situations where mobility is required, for instance in showrooms or road testing.
 Start by configuring a connection (as in the figure on the left) and entering the IP address of the MQTT broker and the corresponding port (1883 by default). Click on the connection and then on the publish button. Now you can add different GUI components to public MQTT messages. In the center figure, we have selected a switch element. Long clicking on the switch takes you to the configuration. In this menu (figure on the right) you should enter the MQTT topic where you want to publish your message (as in ''application/APPLICATION_ID/node/DEVICE_EUI/tx'') and the different messages for the on/off states (as explained in the previous section for mqtt-spy).
@@ Line 57: / Line 57: @@
-===== -. Receiving Downlink Messages =====
+===== - Receiving Downlink Messages =====
-==== -. Autonomo with LoRaBee ====
+==== - Autonomo with LoRaBee ====
 In the LoRaWAN platform, we support devices based on an [[http://support.sodaq.com/sodaq-one/autonomо/|Autonomo]] board with a LoRaBee Microchip RN2483 module. According to [[http://shop.sodaq.com]], Autonomo is a matchbox-sized powerhouse which uses the new Atmel Cortex M0+ 32bit micro controller. One advantage of such device is that it can be powered by a smartphone-sized solar panel. In order to configure the Autonomo with LoRaBee device, you can refer to [[deploying_lorawan|Deploying an End-to-End LoRaWAN Platform]].
 This sketch {{ ::example-code-autonomo.ino.zip |}} can be used as an example. The following extract denotes the part corresponding to receiving downlink messages. For example, the received value can be used to trigger some action on the Arduino module.
-<code c++>
-case EV_TXCOMPLETE:
-      Serial.println(F("EV_TXCOMPLETE (includes waiting for RX windows)"));
-      if (LMIC.dataLen) {
-        // data received in rx slot after tx
-        Serial.print(F("Data Received: "));
-        Serial.write(LMIC.frame + LMIC.dataBeg, LMIC.dataLen);
-        Serial.println();
-      }
-</code>
-==== -. Arduino with Dragino Shield ====
-Devices in the LoRaWAN platform can also be implemented on Arduino boards with Dragino shields. The combined module as well as the basic configuration steps are presented in [[simple_lora_prototype|Simple Prototype of LoRa Communications]]. Similarly to the Autonomo device, you can download the following sketch {{ ::example-code-arduino.ino.zip |}} and modify it according to your preferences. Below you can find an extract of the receiving function for downlink messages.
 <code c++>
@@ Line 107: / Line 94: @@
 }
 </code>
+==== - Arduino with Dragino Shield ====
+Devices in the LoRaWAN platform can also be implemented on Arduino boards with Dragino shields. The combined module as well as the basic configuration steps are presented in [[simple_lora_prototype|Simple Prototype of LoRa Communications]]. Similarly to the Autonomo device, you can download the following sketch {{ ::example-code-arduino.ino.zip |}} and modify it according to your preferences. Below you can find an extract of the receiving function for downlink messages.
-===== -. Selecting the Receive Windows =====
+<code c++>
+case EV_TXCOMPLETE:
+      Serial.println(F("EV_TXCOMPLETE (includes waiting for RX windows)"));
+      if (LMIC.dataLen) {
+        // data received in rx slot after tx
+        Serial.print(F("Data Received: "));
+        Serial.write(LMIC.frame + LMIC.dataBeg, LMIC.dataLen);
+        Serial.println();
+      }
+</code>
+===== - Selecting the Receive Windows =====
 The selection of the receive window is one important parameter in receiving downlink messages. Thus, you should note these two important limitations:
@@ Line 118: / Line 117: @@
 [{{ undefined:loraserver-downlink-dr.png?durect&650 | Figure 3. Receive window selection on loraserver backend}}]
+<WRAP center round tip 60%>
+Without configuring the receive window, with OTAA mode, autonomo is receiving on RX1.
+</WRAP>