Understanding ADR scheme's choices

[Jaco Marais]

Hello, I’m trying to understand the ADR scheme’s behaviour.

My setup uses an ADRStep of 30 and nodes can be assigned from SF12BW1250 to SF7BW250. The node in question is an RN2483.

Based on http://www.multitech.net/developer/software/lora/introduction-to-lora/ I know that the SNR value from each packet is used and a data rate is calculated per sample. Samples from the last 11 packets are used and the maximum data rate that meets an unknown threshold will be sent to the device.
Based on http://www.multitech.net/developer/forums/topic/explanation-of-adr-implementation/ I know the SNR values that are used in the data rate calculation.
DR0 < -15 dB, DR1 > -15 dB, DR2 > -12 dB, … DR5 >-3 dB DR6 > 0 dB

I have here some values for a specific node, in general, it’s SNR is above 0 yet here it goes from SF10 to SF12, staying at SF12 even though there is a stretch of more than 11 packets for which the SNR is >0 before moving to SF7. I have marked the stretch with *’s.

SNR (dB) SF      BW
2.20	10	125
-1.00	10	125
6.00	10	125
-5.00	10	125
5.00	10	125
-0.20	10	125
2.80	10	125
0	10	125
3.20	10	125
5.20	10	125
4.80	10	125
-0.20	10	125
5.00	10	125
4.20	10	125
-3.80	10	125
-0.50	10	125
-8.20	10	125
3.20	10	125
4.20	10	125
-1.80	10	125
4.80	10	125
3.50	10	125
3.50	11	125
5.20	11	125
0.80	11	125
5.00	11	125
-6.00	11	125
2.00	11	125
1.20	11	125
-1.80	11	125
3.80	11	125
4.20	11	125
-8.00	11	125
5.20	11	125
3.50	11	125
5.20	11	125
2.00	11	125
5.00	11	125
-10.50	12	125
3.50	12	125
-0.50	12	125
4.50	12	125
3.20	12	125
-13.80	12	125
3.50	12	125 *
5.20	12	125 *
3.50	12	125 *
1.00	12	125 *
4.50	12	125 *
3.00	12	125 *
3.20	12	125 *
3.00	12	125 *
4.50	12	125 *
1.80	12	125 *
2.20	12	125 *
2.50	12	125 *
4.00	12	125 *
-0.50	12	125
1.80	12	125
-7.80	12	125
3.50	12	125
5.50	12	125
4.80	12	125
2.50	12	125
1.00	12	125
4.50	12	125
-2.50	7	125
3.00	7	125
0	7	125
2.00	7	125
0.20	7	125
5.80	7	125
-2.00	7	125
-4.80	7	125
2.80	8	125
-6.80	8	125
9.80	8	125
8.50	9	125
7.00    9	125

Can you explain the ADR scheme’s behaviour here? Perhaps my understanding of how it calculates data rates are wrong?

• This topic was modified 5 years, 4 months ago by Jaco Marais.
• This topic was modified 5 years, 4 months ago by Jaco Marais.

[Jason Reiss]

What version of network server is being used?

SNR > 0 will allow SF7
What ADR commands are being sent to the end-device?

$ mosquitto_sub -v -t lora/+/+

Normally ADR will not reduce the datarate using commands.
Why doe the datarate degrade from SF7 so quickly at the end of this sequence?

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