AT+QCSQ reliability vs timing after power-up (BG95)

IoT Modules LPWA Module
1

Hello all,

I have an IoT use-case with module fully powered down most of the time.
With low duty cycle I need to power-up and transmit data, everything is working well but I was looking for ways to estimate the radio link quality and it looks like AT+QCSQ does not a great job at it for first seconds after power-up. I check on eval board, spaming “AT+QCSQ” after power-up, and got something similar:

[2021-08-10_18:09:47:728]RDY
[2021-08-10_18:09:48:318]AT+QCSQ

[2021-08-10_18:09:48:318]+QCSQ: “NOSERVICE”

[2021-08-10_18:09:48:318]OK
[2021-08-10_18:09:48:729]AT+QCSQ

[2021-08-10_18:09:48:729]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:48:729]OK
[2021-08-10_18:09:49:073]AT+QCSQ

[2021-08-10_18:09:49:073]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:49:073]OK
[2021-08-10_18:09:49:358]AT+QCSQ

[2021-08-10_18:09:49:358]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:49:358]OK
[2021-08-10_18:09:49:720]AT+QCSQ

[2021-08-10_18:09:49:720]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:49:720]OK
[2021-08-10_18:09:50:096]AT+QCSQ

[2021-08-10_18:09:50:096]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:50:096]OK
[2021-08-10_18:09:50:260]
[2021-08-10_18:09:50:260]APP RDY
[2021-08-10_18:09:50:411]AT+QCSQ

[2021-08-10_18:09:50:411]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:50:411]OK
[2021-08-10_18:09:50:743]AT+QCSQ

[2021-08-10_18:09:50:743]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:50:743]OK
[2021-08-10_18:09:51:042]AT+QCSQ

[2021-08-10_18:09:51:042]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:51:042]OK
[2021-08-10_18:09:51:374]AT+QCSQ

[2021-08-10_18:09:51:374]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:51:374]OK
[2021-08-10_18:09:51:748]AT+QCSQ

[2021-08-10_18:09:51:748]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:51:748]OK
[2021-08-10_18:09:52:308]AT+QCSQ

[2021-08-10_18:09:52:308]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:52:308]OK
[2021-08-10_18:09:52:625]AT+QCSQ

[2021-08-10_18:09:52:625]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:52:625]OK
[2021-08-10_18:09:52:958]AT+QCSQ

[2021-08-10_18:09:52:958]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:52:958]OK
[2021-08-10_18:09:53:290]AT+QCSQ

[2021-08-10_18:09:53:290]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:53:290]OK
[2021-08-10_18:09:53:579]AT+QCSQ

[2021-08-10_18:09:53:579]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:53:579]OK
[2021-08-10_18:09:53:899]AT+QCSQ

[2021-08-10_18:09:53:899]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:53:899]OK
[2021-08-10_18:09:54:216]AT+QCSQ

[2021-08-10_18:09:54:216]+QCSQ: “eMTC”,-125,0,8,0

[2021-08-10_18:09:54:216]OK
[2021-08-10_18:09:54:593]AT+QCSQ

[2021-08-10_18:09:54:593]+QCSQ: “eMTC”,-62,-86,107,-10

It took 5sec after AP READY to get proper values.

Is this normal? Can I do something to have proper reading before? (5sec is way to long in my application ^^)

Thank you, have a good day,

2

it is normal ， since when you power-up the module , the module will do the network searching procedure ,

in your secnario （ low duty cycle）， i suggest you use EDRX or PSM mode , instead of power-down module dirrectly .

3

Hello Stephen, thank you for you answer.

Actually the duty cycle is so low that even EDRX and PSM are too power hungry compared to full power-down :wink:

To get back to my question: the device is connected as I can send the data successfully but I dont have reliable network quality info for this connexion :frowning: I guess somewhere the information must be available as the “link” is negotiated with the base station right ?

4

Normally ， As you said we use AT+QCSQ to query the signal quality .

and meanwhile , We use TCP retransmission mechanism and QoS to ensure the reliable transmission of data