Field Guide · protocol

Also known as: LoRaWAN, LoRa WAN

LoRaWAN is the open MAC-layer and network protocol that rides on top of the LoRa chirp physical layer, turning long-range radio links into a managed IoT network with addressing, security, and gateways.1 Where LoRa defines how a symbol is sent, LoRaWAN defines how a fleet of battery devices, gateways, and a server cooperate — it is maintained by the LoRa Alliance rather than by the chip vendor. Note that its spread-spectrum PHY uses frequency chirps, not direct-sequence code spreading.

device device device gateway gateway net server app
LoRaWAN is a star-of-stars network: any gateway that hears a device forwards its packet to one network server, which deduplicates and routes to the application.

Overview

A LoRaWAN device does not associate with a single gateway. It simply broadcasts an uplink; every gateway in range forwards the frame to a central network server, which discards duplicates, checks the message integrity code, and passes the payload to the application server. This “network the sky” design means coverage improves just by adding gateways, and devices stay dumb, cheap, and long-lived on a coin cell.

Technical characteristics

Property Value
PHY LoRa chirp spread spectrum (SF7–SF12)
Bands Sub-GHz ISM: EU868, US915, AS923, IN865, …
Data rate ~0.3 kbps (SF12) to ~50 kbps (SF7 / FSK)
Payload ~11–242 bytes depending on data rate
Access Asynchronous ALOHA; adaptive data rate (ADR)
Security AES-128 CMAC/CTR; separate network + application keys
Activation OTAA (join procedure) or ABP (pre-provisioned)

Higher spreading factors trade throughput for range and link budget: SF12 decodes far below the noise floor but occupies the air far longer, so ADR pushes each device to the fastest rate its link can sustain.

Device classes

  • Class A — the mandatory baseline. Each uplink is followed by two short downlink receive windows, then the radio sleeps. Lowest power; downlinks only ride on an uplink.
  • Class B — adds scheduled receive slots synchronized to gateway beacons, so the server can reach a device at predictable times without waiting for it to talk first.
  • Class C — receives continuously except while transmitting. Lowest latency but highest power, so it suits mains-powered actuators rather than battery sensors.

History

The LoRaWAN specification was first published by the LoRa Alliance in 2015, standardizing the network layer above Semtech’s LoRa PHY.2 Regional parameter documents and the 1.0.x and 1.1 specification lines followed, adding roaming, class refinements, and tightened key handling.

Deployment

LoRaWAN backs public and private IoT networks worldwide — utility metering, agriculture, asset tracking, and building sensors — including community networks such as The Things Network. It competes with cellular LPWANs like NB-IoT and Sigfox, trading carrier SLAs for unlicensed-band autonomy.

Decoding it with GopherTrunk

LoRaWAN is outside GopherTrunk’s scope: GopherTrunk is a trunked land-mobile voice scanner (P25, DMR, NXDN, TETRA, …), not an IoT gateway. LoRaWAN frames are readily visible on an SDR waterfall as the diagonal chirps of LoRa, and general-purpose tools plus a gateway concentrator can receive them, but decoding the payload also requires the device’s AES keys. GopherTrunk neither implements the MAC layer nor manages keys.

Sources

  1. LoRa — LoRaWAN — Wikipedia, for the MAC-layer role above the LoRa PHY, device classes, and star-of-stars topology. ↩

  2. About LoRaWAN — LoRa Alliance, for the specification’s stewardship, security model, and network architecture. ↩

See also