Understanding LoRaWAN
LoRaWAN is a wireless protocol built around a simple tradeoff: sacrifice bandwidth for range and power efficiency. A LoRaWAN device can transmit small packets (sensor readings, GPS coordinates, status updates) over several kilometers while running on a battery for years.
This makes LoRaWAN ideal for applications where devices need to report data infrequently and operate unattended: agricultural sensors, asset trackers, smart meters, environmental monitors.
How Data Flows
A LoRaWAN device doesn't connect directly to the internet. Instead, it broadcasts a radio signal that any nearby gateway can receive. The gateway forwards the message to a LoRaWAN Network Server (LNS), which authenticates the device, decrypts the payload, and delivers it to your application.
Multiple gateways can receive the same transmission. The network server deduplicates these messages and selects the best one based on signal quality. This redundancy improves reliability without requiring anything special from the device.
Device Keys
Every LoRaWAN device is provisioned with cryptographic keys that authenticate it to the network and encrypt its data. Every device, custom built or off the shelf, has three identifiers:
DevEUI: A unique 64-bit address that identifies the device globally, similar to a MAC address.
JoinEUI: Identifies which network server should handle the device's join request. On Helium, this is how the Packet Router knows where to send your device's traffic.
AppKey: A secret root key shared between the device and network server. During the join process, both sides use this key to derive session keys for encrypting data.
These keys ensure that even though your device's radio signals are received by public gateways, only your network server can read the contents.
On the Helium Network
Helium Hotspots are LoRaWAN gateways. When a device transmits, any Hotspot in range receives it and forwards the packet to the Helium Packet Router. The router uses the JoinEUI to determine which LNS should receive the data, then delivers it there.
This architecture means a single device can roam across the entire Helium network without configuration changes. Any Hotspot will pick up its signal and route it correctly.
For deeper technical details on LoRaWAN, see The Things Network Learn or the LoRa Alliance LoRaWAN 1.0.2 Specification.