LTE_LC_MODEM_EVT_SEARCH_DONE event not delivred on periodic search

[erco_JBV]

Hello,

I am implementing the periodic search for lte managment (using SDK 2.5.2 on a nrf9160).

The periodic configurations in struct lte_lc_periodic_search_cfg  is:

                .loop = false ;

                .return_to_pattern =  0;

                .band_optimization = 1; (data_profile = LOW_POWER)

 

And two following pattern :

- The first is range pattern type, with values : initial_sleep = 10, final_sleep = 40, time_to_final_sleep = -1, pattern_end_point = 1

- The second is table type with values : val_1 = 30, val_2 = -1, val_3 = -1, val_4 = -1, val_5 = -1

All periodic search tests are carried out using a Faraday cage, and network activity is measured with an ampere meter.

When the network is requiered, I received the event LTE_LC_MODEM_EVT_LIGHT_SEARCH_DONE , at next the modem switch to limited_service.

In the ampere meter, the periodic search works. Both pattern are executed with the right sleep values. However, at the end the search keep looping on the last pattern and never sends the LTE_LC_MODEM_EVT_SEARCH_DONE event. Even if a network was found, none event was delivred.

Why the search doesn’t stop and why the LTE_LC_MODEM_EVT_SEARCH_DONE event is never generated?

 

Thank you for your help

[dejans]

Hi,

Can you provide more information about your application?

All periodic search tests are carried out using a Faraday cage, and network activity is measured with an ampere meter.

Can you provide more information on what you measured with an ampere meter?

In the ampere meter, the periodic search works.

Can you rephrase this? How does periodic search work in ampere meter?

However, at the end the search keep looping on the last pattern and never sends the LTE_LC_MODEM_EVT_SEARCH_DONE event. Even if a network was found, none event was delivred.

Can you elaborate on this? What happens when it loops on the last pattern? 

Best regards,
Dejan

[erco_JBV]

Hi,

I'm implementing a lte connectivity management module, with APN, PSM management and area cell network search.

I am testing periodic searches when the modem can't find a network to connect to.

The faraday cage allows to block any incoming network to trigger the periodic search. The amperemeter shows the power consumption, to control when the modem is in sleep mode and when it is ON to search networks.

In the following example, I used this configuration for my periodic searches (struct lte_lc_periodic_search_cfg):

loop = false ;

return_to_pattern = 0 ;

band_optimization = 1 ; (data_profile = 1)

I used just one table pattern with values:

val_1 = 10 ; val_2 = 10 ; val_3 = 20 ; val_4 = 35 ; val_5 = -1.

 

This image shows the current readings taken by the ampere meter:

 

Before the first period: the modem has already been connected to a cellular network and is in idle mode.

At the beginning of the 1^st period, the modem switches to PSM mode and after that, I close the faraday cage. Then, the light search is performed and fails. The event LTE_LC_MODEM_EVT_LIGHT_SEARCH_DONE is generated at the end of the 1^st period. On this event, the library switches to limited-service mode to ensure the periodic search.

 

On the second period: the modem starts the periodic search according the configuration table type : sleep 1 = 10 seconds / search / sleep 2 = 10 seconds / search / sleep 3 = 20 seconds / search / sleep 4 = 35 seconds -> end of pattern (no loop).

 

On the third period: the modem continues to perform the search only based on the last configuration table value (35 seconds): search / sleep 4 = 35 seconds / search / sleep 4 = 35 seconds / search / sleep 4 = 35 seconds… again and again and it goes on indefinitely.

Why in this period, the model is made in this way?

I was expecting the pattern to stop and to receive the LTE_LC_MODEM_EVT_SEARCH_DONE event.

Why the search never stops and why the LTE_LC_MODEM_EVT_SEARCH_DONE event is never generated?

 

Are there any incomplete or missing configurations?

 

Best regards,

JBV

[dejans]

Hi JBV,

I will discuss this with our modem team. I will get back to you by the end of this week.

Best regards,
Dejan

[dejans]

Hi JBV,

Which modem firmware version do you use?

Could you please provide a modem log?

Best regards,
Dejan

[erco_JBV]

Hi Dejan,

The modem firmware version that I use is the 1.3.6.

About modem logs, I don't have any available serial port on my custom board for logs.
I don't find any way to get them. I only have SWD or RTT.
Do you have any suggestion to catch them?

Best regards,
JBV

[dejans]

Hi JBV, 

You can get information about modem tracing in modem trace module documentation. Specifically, you can look at modem tracing with RTT. You can also look at this discussion.

Best regards,
Dejan

[dejans]

Hi JBV,

Were you able to get modem log? Could you please provide status update?

Best regards,
Dejan

[erco_JBV]

Hi Dejan,

Here are the modem logs collected with the following periodic search configuration:

loop: 0, return to pattern: 0, band optimization: 1, pattern count: 2

- Range pattern: initial sleep: 25, final sleep: 40, time to final sleep: -1, end point: 1
- Table pattern: val_1: 10, val_2: 10, val_3: 20, val_4: 35, val_5: -1

Best regards,

JBV

7571.RTTLogger_Channel_modem_trace.log