5.3.6) LoRaWAN IoT

Overview

AERPAW has installed a LoRaWAN system comprising currently seven LoRaWAN gateways (one at each of the nodes in Lake Wheeler, as well as CC2 and CC3) and the network infrastructure to collect and visualize both the data as well as the associated meta-data.

The figure above depicts the AERPAW LoRaWAN setup, which allows multiple tenants to share the gateway and network infrastructure while having completely private databases. The figure depicts two tenants with disjoint sets of LoRa sensors (on the left). The LoRa sensors transmit data to the LoRa gateways, which in turn forward the data to the LoRa network housed in the AERPAW cloud. The common part of the LoRa network receives the data and sorts it according to the tenant and forwards the information to a Postgress database. A graphana visualization can be remotely accessed to inspect the results.

The setup follows closely the setup from Purdue University (many thanks to Andrew Blamos for his help).

LoRa Sensors

Any compatible LoRaWAN sensors can (or should be able to) be connected to the AERPAW LoRaWAN network. AERPAW has a collection of several LoRaWAN sensors, including several GPS, temperature, and humidity sensors; however, it is expected that the Experimenters will bring their sensors (or AERPAW will purchase them) according to the type of experiment sought.

An interesting possibility is offered by AERPAW with the availability of Ronoth's LoStik sensors, which (with the proper software) can transform any host computer (including our portable nodes) into a LoRaWAN sensor. More details are available at this page.

LoRa Gateways

The AERPAW LoRaWAN gateways are RAK7289V2 - equipped with 16 channels, operating in the 915MHz ISM band, and using Ethernet as the backhaul technology. The gateways can be connected on the backend to ChirpStack v3, TTN/TTS, AWS IoT Core for LoRaWAN, AWS IoT core integration, and Actility LNS with Basics Station. We use ChirpStack v3.

Each gateway is installed at the top of each of the AERPAW towers (~20m height when extended and ~10m height when retracted), and on top of the buildings at CC2 and CC3.

Upon receiving a LoRaWAN packet each gateway reports to the network backend the following information:

the data being received
metadata
- snr
- rssi
- time of reception
- channel
- rfChain
- region name
- gatewayId
- location (latitude, longitude, altitude)
- gatewayId and uplinkId

LoRa Common Software

The network software is based on the ChirpStack open software and it is containerized (using Docker containers). The ChirpStack Gateway Bridge (CS in the picture above) is a service that converts LoRa packet forwarder protocol into ChirpStack common data format. NATS is an open-source messaging system allowing for the segregation of the messages from the gateways according to the different tenants.

LoRa Tenant Software

Software for each tenant is instantiated on a separate set of containers to ensure isolation between tenants. The data coming from NATS first goes to the ChirpStack container (CS) which provides an interface allowing the selection of the incoming data into the database. ChirpStack stores device sessions, metrics, and cache into an (in memory) Redis database. PostgresSQL is used for permanent storage. Prometheus is used for online monitoring, and Grafana is used to display the results.

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