Power saving mode (PSM)

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PSM lets the device enter deep sleep while it maintains its network registration. You configure PSM with the following Kconfig options:

  • Periodic tracking area update (TAU): Controls how often the device updates its location with the network. Set the interval in seconds with the following option:

    # Configure TAU in seconds
CONFIG_LTE_PSM_REQ_RPTAU_SECONDS=7200  # 2 hours (default in prj.conf)

  • Requested active time (RAT): Defines how long the device stays active after a wake-up. Set the duration in seconds with the following option:

    # Configure RAT in seconds
CONFIG_LTE_PSM_REQ_RAT_SECONDS=6  # 6 seconds (default in prj.conf)

When PSM is enabled, the following applies:

  • The device negotiates the PSM parameters with the network.
  • PSM helps achieve longer battery life.
  • The device remains registered but unreachable during sleep.
  • The device wakes up periodically, based on the TAU setting.
  • The device stays active for the duration specified by RAT.

For more information on power configuration, see Application power configuration.