NBIOT TX Consumption vs LTEM

[maupicco]

In my device that uses NBIOT I am modifying the FW to use LTEM.

During the tests I have shown that the consumption of LTEM transmission for the same amount of data sent is about 5 times higher.

I simulated the same behavior using the example of SDK 1.8.0 present in the folder ncs \ v1.8.0 \ nrf \ samples \ nrf9160 \ udp

I am using a data SIM from deutsche telekom which has roaming in Denmark with two different operators: Telenor A / S and Telia Danmark

In the UDP project only enabling the NBIOT transmission with the CONFIG_LTE_NETWORK_MODE_NBIOT = y parameter the device is able to communicate and for each transmission of 10 characters the data are the following (see image):

TX time: 1.874 sec 

Total consumption: 39,63 mC

If I set the LTEM mode with the CONFIG_LTE_NETWORK_MODE_LTE_M = y parameter, the transmission time increases and the consumption increases by about 5 times (see image):

TX time: 6.945 sec 

Total consumption: 210.83 mC

I also tried to enable:
UDP_EDRX_ENABLE and UDP_RAI_ENABLE in the example but the consumption is always the same.

The consumptions detected in LTEM are too high to guarantee the required battery life in my project.

Are there other parameters that I can enable / configure in the UDP example to reduce consumption?

The consumptions measured by me are very different from those that can be estimated with Nordic's "POWER PROFILE ONLINE".

Please I need you support to identify the problem.

Thanks

[maupicco]

Hi Didrik,

I'm using the same network (Telenor/Telia). I tested it using the two network with the same result.

I enabled the trace and now I attach the file.

In my version of Tace Collector V2 preview  (v 0.0.11) I don't find the network parameter for OPP. Please give me instruction about it.

LTEM-trace-2022-04-28T15-10-51.693Z.bin

LTEM-trace-2022-04-28T15-10-51.693Z.pcapngNBIOT-trace-2022-04-29T06-25-14.542Z.binNBIOT-trace-2022-04-29T06-25-14.542Z.pcapng

[Didrik Rokhaug]

Looking at your trace, it seems the RRC inactivity timer in the LTE-M network is ~5s.

UDP_RAI_ENABLE in the example but the consumption is always the same.

RAI can help, but is only supported for NB-IoT (control plane RAI) in the udp sample.

[maupicco]

Yes,

it is clear to me that the RCC inactivity timer is about 5 sec.

The big problem is the consumption during the idle period of RCC.
As you can see from the power profile picture, the power consumption in RCC is HIGH.

I don't know how to check the cDRX parameters in use, they seems the problem is power consumption during RCC inactivity.

Is it possible to somehow verify the cDRX parameters?
Is it possible to set the parameters in some way to reduce consumption?

Nordic's online power profiler always shows much lower consumption values in the various configurations.

I would like to be able to discriminate if abnormal consumption is:
- caused by the network provider
- caused by an incorrect configuration of the nordic module.

[Didrik Rokhaug]

What happens while you are in an RRC connection is controlled by the network, and the device does not have any way to affect it (other than how much data is transmitted).

Based on your power profiler trace, it looks like the cDRX interval is set very short in your LTE-M network, which will drastically affect the power consumption.