How does the signal
reach the gateway?
Distance, terrain and buildings affect reception. The SMARTinfeld demo combines these effects into an estimated link margin.
Radio planning →1. Distance weakens the signal
Free-space path loss describes the loss along an unobstructed radio path. At the same frequency, doubling the distance adds about 6 dB of loss. The model uses 868 MHz.
2. Obstacles change the radio path
Radio waves can reach areas behind a roof edge or hilltop. This diffraction costs additional signal strength. What matters is how far an obstacle extends into the radio path and its distance from the transmitter and receiver.
The demo samples terrain and roofs and estimates diffraction losses at dominant edges. The single-edge formula comes from ITU-R P.526. Multiple edges are considered using a limited approximation; the full ITU recommendation is not implemented.
3. The margin is decisive
Transmit power and antenna gain contribute to the received signal level. Cable, path and obstacle losses are subtracted. The remaining margin also takes account of receiver sensitivity and an adjustable planning buffer.
Example: a received level of −115 dBm, sensitivity of −130 dBm and a 10 dB planning buffer give a 5 dB margin. With an additional indoor assumption of 15 dB, −10 dB remains: the point then fails to meet the selected threshold.
What does this mean in practice?
A higher site can reduce shadowing. More gateways can cover additional areas or provide a second reception path. Higher antenna gain improves the margin in this simplified model; real antennas may provide substantially poorer coverage at certain elevation angles.
The display is a prediction. On-site measurements are still needed to check the model assumptions.
The SMARTinfeld calculation model in detail →The original technical source
ITU-R P.526 “Propagation by diffraction” describes methods for calculating diffraction losses. Our single-edge formula is based on edition P.526-16, Section 4.1. The original source includes the derivation and other methods.
ITU-R P.526-16: original source with PDF download (English) ↗