Building a Low Power Wide Area Network

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At Thing Innovations we’re currently developing a Low Power Wide Area Networking (LPWAN) solution based on LoRa Long Range technology. The equipment being used in the project is from MultiTech Systems as this was seen to offer a number of key components that fitted with Thing Innovations design ideas and goals.

Gateway

The gateway is the central point on a small network or one of a number of gateways on a much larger network covering a whole city. For out uses, we have chosen the MultiConnect Conduit with the
LoRa mCard based on the Semtech SX1301 LoRa baseband demodulator. The gateway comes in two versions, one with Node-RED pre-installed as the development environment, the other is a straight mLinux with additional applications to handle the LoRa messages. You would then need to create your own applications to process the received messages. Using the Node-RED version enables an application to be built up very quickly.

Nodes

The edge nodes or sensor devices are being developed using the MultiConnect mDot. The mDots come in two versions with the differences being the conector for the antenna and whether a programming header is included or not. The default configuration is to act as a modem with commands and data transferred to the mDot over the serial interface.
The mDots are based on the Semtech Corporation LoRa chips with a ST Micro STM32F411 as an attached MCU. The advantage the mDots provide other other radio only solutions is that you don’t need to interface to your own MCU. The modules include all you need to produce wireless sensor nodes and are easily re-programmed using the ARM mbed platform.

mDot Developer Kit

In order to program the mDot you need the mDot Developer kit. This includes the appropriate interface to the mDot programming header and enables additional hardware to be developed using Arduino compatible shield headers. (Note, not all the header pins are connected to the mDot, see developer guide for details.).

Development

If development is to be done on the mDot, which is one of its big selling points, then you’ll need to be familiar with the ARM mbed development environment. This is all on-line cloud based although there are ways to setup off-line toolchains. The first place to visit would be the mbed mDot information page. The mDot uses the same MCU as the mbed ST-Nucleo-F411RE where further information can be found.

Device Management

The MultiConnect Conduit is able to connect to the MultiTech DeviceHQ where it can be monitored and managed remotely. The remote management features include scheduling firmware updated and regular reboots as well as identifying when gateways have gone off-line. This is in addition to the local web interface that is used to configure the Conduit in the first instance.

Applications

The LoRa wireless technology is well placed to be used in Smart City and Smart Building applications where many low cost wireless sensors can be deployed for a single gateway. With other ISM band wireless technology this is not possible for any distances over a few hundred metres. As the gateway is running an instance of Node-RED, it is then very easy to send the received sensor data to any cloud based service such as OpenSensors.io or IBM Bluemix for logging and further processing.