RE: Onomondo SoftSIM low power optimization.

SeppoTakalo — Wed, 06 Aug 2025 10:36:52 GMT

For background information there is Nordic academy pages regarding LTE power saving modes: https://academy.nordicsemi.com/courses/cellular-iot-fundamentals/lessons/lesson-1-cellular-fundamentals/topic/lesson-1-power-saving-techniques/

Then, regarding this case, Active time -1 means that there is no PSM. So it stays in eDRX.

I don't see any specific eDRX times requested, try enabling the eDRX and PSM requests, for example like this:

# Configure PSM mode
CONFIG_LTE_LC_PSM_MODULE=y
CONFIG_LTE_PSM_REQ=y
# Request periodic TAU of 12 hours
CONFIG_LTE_PSM_REQ_RPTAU="00101100"

# Set Requested Active Time (RAT) to 30 seconds. Preferably same as the
# configured LWM2M_QUEUE_MODE_UPTIME. Due to NAT/firewall UDP connections are usually
# closed within 30-60 seconds so there is in general no point in setting a longer
# LTE PSM active time.
CONFIG_LTE_PSM_REQ_RAT="00001111"

# Request eDRX mode
CONFIG_LTE_LC_EDRX_MODULE=y
CONFIG_LTE_EDRX_REQ=y

# Requested eDRX cycle length for LTE-M and Nb-IoT
# This should be fine-tuned for the network and the chosen protocol.
# Lowest value is  the most responsive, but uses more energy during the active eDRX period.
# Longer period may cause more CoAP packet drops on server requests.
# "0000" is 5.12 s
# "0001" is 10.24 s
# "0010" is 20.48 s.
CONFIG_LTE_EDRX_REQ_VALUE_LTE_M="0000"
CONFIG_LTE_EDRX_REQ_VALUE_NBIOT="0000"

# Request Paging time window of 1.28 seconds for LTE-M
CONFIG_LTE_PTW_VALUE_LTE_M="0000"

# Request Paging time window of 2.56 seconds for NB-IoT
CONFIG_LTE_PTW_VALUE_NBIOT="0000"

This example is from our LwM2M client. It should stay active for 30 seconds (in eDRX, polling for incoming data), and then drop into PSM mode for low power usage and be unreachable from network at that point.

Then debug from the LTE event handler what values the network accepts. You need to fine-tune the eDRX and PSM for your use-case, not all networks allow PSM.

RE: Onomondo SoftSIM low power optimization.

Hakon — Tue, 22 Jul 2025 10:58:44 GMT

Hello,

can you provide a modem trace where this behavior is reproduced?