This guide briefly explains the architecture and key concepts of a LoRaWAN® network.
LoRaWAN is a Low Power Wide Area Network (LPWAN) protocol designed for low power, long range use cases.
Key Characteristics
The key characteristics of a LoRaWAN
- Long Range: LoRaWAN networks can provide coverage of up to 10+ km in rural areas and 2-5 km in urban environments
- Low Power Consumption: Devices can operate for 5-10+ years on a single battery
- Secure Communication: End-to-end encryption with AES.
- Bidirectional Communication: Supports both upstream and downstream messages.
Data Size and Rates
LoRaWAN is optimized for low data rate communications:
- Payload Size: 51-242 bytes per message*
- Data Rate: 0.3-50 kbps*
- Daily Messages: Typically designed for 1-100 messages per day
- Duty Cycle: Subject to regional regulations (e.g., 1% in Europe)
*Depends on the regional regulations and the spreading factor. Spreading factor is a transmission parameter that balances transmission range against data rate - higher spreading factors reach longer distances but transmit data more slowly.
Typical Use Cases
LoRaWAN excels in applications requiring:
- Long battery life
- Long-range coverage
- Low cost
- Small, infrequent data transmissions
Typical use cases are
- Smart cities (ex: Street lighting control, Traffic monitoring etc)
- Agriculture (ex: Soil moisture monitoring, Irrigation control etc)
- Supply Chain & Logistics (ex: Asset tracking, Cold chain monitoring etc)
- Utilities (ex: Leak detection, Smart metering etc)
- Industrial IoT (ex: Predictive maintenance)
LoRa and LoRaWAN
LoRa is a wireless modulation technique derived from Chirp Spread Spectrum (CSS) technology. It encodes information on radio waves using chirp pulses - similar to the way dolphins and bats communicate! LoRa modulated transmission is robust against disturbances and can be received across great distances.
LoRaWAN is a Media Access Control (MAC) layer protocol built on top of LoRa modulation. It is a software layer which defines how devices use the LoRa hardware, for example when they transmit, and the format of messages.
The LoRaWAN protocol is developed and maintained by the LoRa Alliance. The first LoRaWAN specification was released in January 2015. At the time of this writing the latest specifications are 1.0.4 (in 1.0 series) and 1.1 (1.1 series).
Architecture
A typical LoRaWAN network consists of the following basic elements.
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End Devices: Sensors or actuators send LoRa modulated wireless messages to the gateways or receive messages wirelessly back from the gateways.
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Gateways: Specialized devices that receive messages from end devices and forward them to the Network Server, as well as forward messages from the Network Server to the end devices.
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Network Server: Software running on a server that manages the entire network. Also referred to as LoRaWAN Network Server/LNS or simply Network software.
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Application: Software running on a server that is responsible for securely processing application data.
Simple message flow
Uplinks
The messages that originates from an end device and are sent to the server via gateways are called an Uplinks.
End devices communicate with nearby gateways and each gateway is connected to the Network Server.
LoRaWAN networks use an ALOHA based protocol, so end devices don’t need to pair with specific gateways. Messages sent from end devices travel through all gateways within range.
These messages are received by the Network Server. If the Network Server has received multiple copies of the same message, it keeps a single copy of the message and discards others. This is known as message deduplication.
The Network Server separates the network settings related data from the separately-encrypted application (sensor) data and forwards the latter to the application server.
The Application Server decrypts the application data and makes is available to the user via a multitude of options.
Downlinks
Messages that originate in the server (Network Server or Application) and are sent to the end device via gateways are called downlinks.
Security
All LoRaWAN data is encrypted using symmetric keys. All devices have one or two unique keys called the “root keys” associated with them, depending on the version of LoRaWAN they use.
These root keys are used to derive separate keys for the application data and network data.
Application data is encrypted using one of these derived keys. This key is known only to the Application Server and the End Device.
Network (settings) data is encrypted using different key(s). These keys are known only to the Network Server and the End Device.
These keys are called Session Keys since they are rotated when a device session changes. Device sessions are a much deeper topic and is omitted from this basic guide in the interest of simplicity.
The Things Stack
The Things Stack is a LoRaWAN® Network Server stack which is the critical component for any LoRaWAN solution. This guide quickly gets the reader up to speed with the basics of The Things Stack.
The Things Stack is an enterprise grade LoRaWAN server (that includes both the Network Server and Application Server functions mentioned in the LoRaWAN Reference architecture). In addition, The Things Stack contains services and tools to securely manage millions of LoRaWAN devices in production.
Now that you are up to speed with the basic concepts and terminology, let’s move on to the hands-on part by getting your starter kit and (optionally) creating a The Things Stack account.