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LoRaWAN across a farm and village. A parish of fields with a soil probe in each one. Two gateways, on the water tower and the church spire, hear them all.

Layers

Scenario

A parish of fields with a soil probe in each one. Two gateways, on the water tower and the church spire, hear them all.

01/05

500 MHz

1 GHz

2 GHz

5 GHz

10 GHz

20 GHz

40 GHz

EU868 LoRaWAN: 863–870 MHz · λ 35 cm · LPWAN, 1 % duty cycle · LoRa Alliance RP002-1.0.4

Network scenes

LoRaWAN across a farm and village

Soil probes in every field report to gateways on the water tower and the church spire; the adaptive data rate, time on air and duty cycle are computed from the link budget.

The place: Rural village and farmland

In this scene

Gateway on the water tower
An outdoor LoRaWAN gateway at the top of the water tower: it hears every probe in the parish at the fastest data rate. (LoRaWAN L2 1.0.4 (TS001-1.0.4), LoRa Alliance RP002-1.0.4)
Scene input: end devices 14 dBm EIRP, gateway antenna 3 dBi, 10 dB fade margin
Gateway in the church spire
A second gateway in the spire: every uplink is heard by both, so either can fail. (LoRaWAN L2 1.0.4 (TS001-1.0.4), LoRa Alliance RP002-1.0.4)
Soil-moisture probe and end device
A probe at three depths with a LoRaWAN radio on a short post: one 20-byte reading every 15 minutes. (LoRaWAN L2 1.0.4 (TS001-1.0.4), LoRa Alliance RP002-1.0.4, ETSI EN 300 220-2)
Network server (in the cloud)
De-duplicates the uplinks heard by both gateways, runs the adaptive data rate and hands the readings to the farm application. (LoRaWAN Backend Interfaces 1.0 (TS002))

Links and interfaces

Backhaul to the network server
Each gateway forwards what it hears over the village fibre or a cellular link. (LoRaWAN Backend Interfaces 1.0)

Computed for this scenario

Gateways in service
2 of 2
End devices served
40 of 40
Mean spreading factor
SF7.0
Mean time on air, 20 B
57 ms
SF12 ring radius
24.7 km
Uplinks an hour at SF12 under 1 % duty cycle
27

Scenarios

Two gateways
Every probe is heard by both gateways at SF7.
Tower gateway down
The water-tower gateway fails; the spire gateway alone still closes every link.
US915 plan
The same farm on the US915 channel plan: dwell-time rules replace the duty cycle.

Tour transcript

  1. A parish of fields with a soil probe in each one. Two gateways, on the water tower and the church spire, hear them all.
  2. The water-tower gateway: at this height the whole parish is inside its SF7 ring.
  3. A soil probe and its end device: 20 bytes every 15 minutes, 57 ms on air at SF7.
  4. The tower gateway fails; the spire gateway alone closes every link, at a higher SF for the far fields.
  5. Both gateways forward to the network server, which removes duplicates and runs the adaptive data rate.

How the numbers are computed

Path loss is Okumura–Hata for open areas at 868 MHz with the gateway height above the ground. Sensitivity per spreading factor is −174 dBm/Hz + 10 log10(125 kHz) + 6 dB + the demodulation SNR (−7.5 dB at SF7 to −20 dB at SF12); a device takes the lowest SF that closes with a 10 dB margin. Time on air follows the LoRa modem formula for a 20-byte payload; the duty cycle is the 1 % of the EU868 g1 sub-band.