First LTE event/connect take some time on my custom board

[simon884]

Hi,

After some difficulty in obtaining the modem trace file, I'm here to have help about connectivity issue. I have a custom board build with an nRF9151, I use Onomondo softSim. So my issue is strange, on my custom board the first LTE event/connect always appears after 3m30/3m35.

Here is an termina output example, as you can see, event coming around 3m30. I did maybe 20 test, different day, etc, and it always take 3m30...

*** Booting nRF Connect SDK v3.5.99-ncs1-1 ***
[00:00:00.777,282] <inf> GCG_DNV: SoftSIM sample started.
[00:00:01.146,362] <inf> GCG_DNV: Waiting for LTE connect event.

+CEREG: 2,"9682","01628305",7

[00:03:27.068,634] <inf> GCG_DNV: LTE cell changed: Cell ID: 23233285, Tracking area: 38530
+CSCON: 1

[00:03:27.115,173] <inf> GCG_DNV: RRC mode: Connected

+CEREG: 5,"9682","01628305",7,,,"11100000","11100000"

[00:03:32.362,152] <inf> GCG_DNV: Network registration status: Connected - roaming
[00:03:32.362,304] <inf> GCG_DNV: LTE connected!

Return of CESQ after LTE connected

+CESQ: 99,99,255,255,15,54

And return of AT+CGMR

mfw_nrf91x1_2.0.2

3056.test_rtt.bin

Is it normal? For example with DK board first LTE event coming at about 1min...

It's look like my modem do nothing between 1s and 3min and half, the only things I see lot of RRC event during 3min and half

[ketiljo]

How do the board look like? What kind of antenna are you using? Long connection time can indicate an antenna problem.

[simon884]

here is my antenna: https://www.mouser.fr/ProductDetail/TE-Connectivity-Linx-Technologies/ANT-LPC-FPC-100?qs=OTrKUuiFdkZAr4qk8G4dFg%3D%3D

Maybe it's the antenna, but why first LTE event ALWAYS occurs between 3min and half and 3min40

[dejans]

Hi,

Initial network search takes time. Maybe you can consider locking bands/PLMN. You can find similar problem described in this discussion.

Best regards,
Dejan

[simon884]

Ok and you don't find it strange that it's always the same time, give or take a few seconds? Whatever the indoor outdoor exposure rain or shine? Is it normal depending on my configuration that it is always 3 minutes 30 ?

For example if I did AT+COPS? my boards return directly available networks, so if my antenna is so bad and if network search take times, why send this AT command works directly ?

If I understand well the link you provide, using lte_lc_power_off() can offer speed connectiona fter the first connection? Should lte_lc_power_off() save in nvm? What happened if I totaly loss power?

[simon884]

I've tried to restric country with AT%XCOUNTRYDATA=208 but I always got ERROR response. before sending AT%XCOUNTRYDATA I've send AT+CFUN=0

[dejans]

Hi,

Can you show your complete AT%XCOUNTRYDATA command?
Can you show the ERROR response you get?

Have you tried to use %XBANDLOCK and %PALL?

simon884 said:

If I understand well the link you provide, using lte_lc_power_off() can offer speed connectiona fter the first connection? Should lte_lc_power_off() save in nvm? What happened if I totaly loss power?

lte_lc_power_off() is setting the modem to power off state. When modem is powered off, certain AT command configuration and network information is preserved in NVM and available even after reset (more information can be found here). This could decrease connection establishment time after first connection.

Best regards, 
Dejan