More about LoRaWAN® radio statistics

This topic provides quick access to the definitions and computations of the radio statistics that build the charts used to monitor LoRaWAN® devices in Device Manager. For more information, see Monitoring radio statistics of a LoRaWAN® device.

Packet Error Rate (PER)

A percentage ratio of missing uplink packets to total uplink packets that defines the quality of uplink communication between the device and the network. It provides a view on the packet loss.

Its computation depends on the ADR algorithm version set in the connectivity plan associated with the device. For more information, see Monitoring radio statistics of a LoRaWAN® device.

Instant PER

Instant PER represents the short-term view of the packet error rate. It is computed based on a short sliding window. Hence it gives the most recent view of the uplink instantaneous PER, but it might be subject to high volatility.

If the device is associated with a connectivity plan using ADRv3, then Instant PER is evaluated over the last two received uplink frames by the network. Example: If the last uplink frame received has a frame counter equal to 26 and the previous one has a frame counter equal to 24, then Instant PER is 1/3 or 33% (one packet lost over 3).

Otherwise, if the device is associated with a connectivity plan using ADRv2 (legacy ADR algorithm), then Instant PER is evaluated over a sliding window of the last N received uplink frames. N, being 50 by default, depends on the network configuration.

note

When Instant PER equals to zero, it means that there is no error in the reception of the uplink packets by the device.

Instant PER with All LRRS in range is computed without any consideration for any LRR, whereas Instant PER per LRR is computed considering only the uplink frames received by a specific LRR.

Mean PER

Mean PER represents the longer-term estimation of the uplink packet error rate. Hence it is less volatile and better represents the overall quality of the uplink communication between the device and the network.

If the device is associated with a connectivity plan using ADRv3, then Mean PER is evaluated using a forgetting factor K (0.15 by default) applying the following formula: Mean PER (new) = Mean PER (current) * (1-K) + Instant PER (K).

Otherwise, if the device is associated with a connectivity plan using ADRv2 (legacy ADR algorithm), then Mean PER is computed the same way as ADRv3 formula but with K=0.05.

Estimated Signal Power (ESP)

Estimates the real received signal strength of a desired signal considering the impact of background noise.

Being the received signal strength of the useful signal, it represents the S component in the Signal-to-Noise Ratio (SNR) formula. Therefore, ESP can be computed as follows:

• ESP = Tx EIRP – Path Loss + Rx antenna gain
• ESP = RSSI – 10*LOG( 1 + 10(-SNR/10) )

Allows assessing how good the received signal is compared to the minimum sensitivity level of the receiver. It is expressed in dBm and always has negative values.

Received Signal Strength Indicator (RSSI)

Determines the total received signal strength within a channel bandwidth summing up the useful signal (S), the interference (I), and the background noise (N).

Expressed in dBm, RSSI is the sum S + I + N.

Signal-to-Noise Ratio (SNR)

Determines the quality of the reception through the ratio between the received signal strength of the useful signal (S), and the signal strength of the interference (I) added to the one of the background noise (N).

It is computed like this: SNR = S/(I+N). It is expressed in dB.

The higher the SNR (for instance positive SNR as opposed to negative SNR), the better the reception quality.

Spreading Factor (SF)

Determines the data rate used during transmission.

LoRaWAN® SF range is [7..12]: SF7 corresponds to the fastest data rate (~5.5 Kbits/sec), while SF12 corresponds to the slowest data rate (~300 bits/sec).