Using RSSI Data for LoRa Network Path Loss Modeling

RSSI is typically used for the input power estimation in wireless sensor networks. It is necessary to consider the nonlinearity of the receiver amplitude response, which depends on the RSSI circuitry, and the effects of multipath propagation, which are inevitably present in the open space measurements of the actual input power. The paper proposes a method for calculating the input power of a LoRa receiver by adding a certain offset coefficient to the RSSI values. This coefficient was obtained experimentally for LoRa platforms with a signal frequency of 433 MHz, 868 MHz and 2.4 GHz and various spreading factor values. The proposed technique makes it possible to estimate propagation path losses with an accuracy sufficient for estimated calculations. The loss estimation error does not exceed 10–12 dB depending on the distance.