Network connection (PDCCH,PRACH) after PSM

IoT Modules LPWA Module
1

Hello,

I use BC95-G Modem with UEMonitor and i am trying to understand connection procedure to eNB after PSM mode…

I could read when modem go out psm mode and we will try to send data, the UE send PRACH frames (x3) and the eNB answering with PDCCH frame (contain TA, UL Grant and TC-RNTI(and i’m interested by these informations)
image

But when i read logs below of PSM mode + UDP frame i didn’t find any “PDCCH” with TA,UL Grant and RNTI information…
TEST2.Zip (246.7 KB)

Do you have an idea ? and how to obtain TA, UL Grant and RNTI informations ?

Thank’s for your help :slight_smile:
jojon

2

Please refer to the below screenshots

image
image1366×768 96 KB

3

Thank you Herbet for crnti infromation.
I should find corresponding TA and UL Grant :slight_smile:

How to know if my modem is in PSM mode ?
I have try this command “AT+CPSMS=1,01000001,00100001”

And i have this response from debug

image
image1587×797 11.4 KB

i dont know if my module is in PSM mode, how verify please ?
Thank’s for your help

4

Please execute the command, if enter PSM, can output the corresponding URC

AT+NPSMR=1

Maybe, trace the log and execute the following Commands and make sure the URC output of the PSM. You upload the log and I will help you confirm from the signaling

AT+CFUN=0
AT+CFUN=1
AT+CGATT=1

5

Hello herbert,
thank for your help!
Below the log and traces of AT commands.
forherbert.Zip (250.6 KB)

AT+NPSMR=1
AT+NPSMR=1
OK
AT+CFUN=0
AT+CFUN=0
+NPSMR:0

OK
AT+CFUN=1
AT+CFUN=1
OK
AT+CGATT=1
AT+CGATT=1
OK

+NPSMR:1

Thanks :slight_smile:

6

image
image1366×729 60.1 KB

7

You should check the network reply regarding your PSM values.
With at+cpsms the module will send the requested PSM values to the network.

If and which PSM values the network will grant you is reflected in at+cereg URC/output.

Enable URC with: at+cereg=4 or at+cereg=5

Then request at+cereg? output or wait for URC after setting at+cpsms value.

You’ll receive something like:
+CEREG: 4,5,C2F6,031B7B65,9,,,00000001,10101110

CEREG | Active time (T3324): 00000001 | TAU (T3412): 10101110

TAU: 1 minute x 14 = 14 minutes
T3324: 2 seconds x 1 = 2 seconds

Use e.g. calculation tool to decode the output.