LTE-M consuming way to much power to transmit 100 bytes UDP every 15 seconds, please help me understand why.

RE: LTE-M consuming way to much power to transmit 100 bytes UDP every 15 seconds, please help me understand why.

user91187 — Tue, 08 Mar 2022 10:53:42 GMT

Sorry for the slow response,

There is a way to get an indication when the modem goes to sleep wit one of the power saving features. The XMODEMSLEEP AT command. Its part of the link controller and can be enabled through Kconfig option CONFIG_LTE_LC_MODEM_SLEEP_NOTIFICATIONS.

```

config LTE_LC_MODEM_SLEEP_NOTIFICATIONS
        bool "Modem sleep notifications"
        help
                If this option is enabled the application will get notifications when the modem
                enters and exits sleep. The application will also get pre-warning notifications
                prior to when the modem exits sleep depending on the configured pre-warning time.
config LTE_LC_MODEM_SLEEP_PRE_WARNING_TIME_MS
        int "Modem sleep pre-warning time"
        range 500 3600000
        default 5000
        help
                Time before modem exits sleep that a pre-warning is to be received.
config LTE_LC_MODEM_SLEEP_NOTIFICATIONS_THRESHOLD_MS
        int "Modem sleep notifications threshold"
        range 10240 3456000000
        default 1200000
        help
                Minimum value of the duration of the scheduled modem sleep that triggers a
                notification.

        /** @brief Modem sleep pre-warning
         *         This event will be received a configurable amount of time before
         *         the modem exits sleep. The time parameter associated with this
         *         event signifies the time until modem exits sleep.
         *         The associated payload is the modem_sleep member of type @ref lte_lc_modem_sleep
         *         in the event.
         */
        LTE_LC_EVT_MODEM_SLEEP_EXIT_PRE_WARNING,
        /** @brief This event will be received when the modem exits sleep.
         *         The associated payload is the modem_sleep member of type @ref lte_lc_modem_sleep
         *         in the event.
         */
        LTE_LC_EVT_MODEM_SLEEP_EXIT,
        /** @brief This event will be received when the modem enters sleep.
         *         The time parameter associated with this event signifies
         *         the duration of the sleep.
         *         The associated payload is the modem_sleep member of type @ref lte_lc_modem_sleep
         *         in the event.
         */
        LTE_LC_EVT_MODEM_SLEEP_ENTER,

So this way you can make sure that it does not surpass the threshold. Not sure if it will solve the inconsistency in the power consumption you have.
Regards,
Jonathan

RE: LTE-M consuming way to much power to transmit 100 bytes UDP every 15 seconds, please help me understand why.

user111658 — Fri, 18 Feb 2022 21:28:23 GMT

Hi Jonathan, any updates?

RE: LTE-M consuming way to much power to transmit 100 bytes UDP every 15 seconds, please help me understand why.

user111658 — Thu, 17 Feb 2022 16:14:21 GMT

Jonathan,

While awaiting an answer about what determines the cDRX duty cycle, I'm wondering if there is a way to know when the modem has finished sending all its data.

When using the RAI feature, if we send more than 600 bytes or so, I notice there are two outgoing transmissions. I imagine this is because the modem was not able to send out all data before we indicated there was not more data with the RAI_NO_DATA socket option.

If we can know when all the data has been transmitted, then I can better time the use of the RAI_NO_DATA option to conserve power.

RE: LTE-M consuming way to much power to transmit 100 bytes UDP every 15 seconds, please help me understand why.

user91187 — Thu, 17 Feb 2022 08:47:56 GMT

The network is mostly in control of the timing so cDRX is not something that the device has control over. I dont have a good answer i am consulting our internal experts and i will update.

Regards,
Jonathan

RE: LTE-M consuming way to much power to transmit 100 bytes UDP every 15 seconds, please help me understand why.

user111658 — Wed, 16 Feb 2022 21:04:51 GMT

Jonathan,

There are times when the RRC connected period looks much cleaner and one can determine a consistent cDRX active/inactive period. The current consumption is more than halved around 11mA. What would cause this outcome over the other where it looks like the radio is constantly on and current consumption is much higher?

Thanks,

Eric

RE: LTE-M consuming way to much power to transmit 100 bytes UDP every 15 seconds, please help me understand why.

user111658 — Wed, 16 Feb 2022 15:21:44 GMT

Hi Jonathan,

Version is 1.6.1.

Since posting this I was able to make significant improvement using RAI and socket options to get an early RRC release to idle. I guess I'm surprised most by the 2nd power profile image where the signaling is almost constant and there is no discernable/regular cDRX duration and inactivity period.

RE: LTE-M consuming way to much power to transmit 100 bytes UDP every 15 seconds, please help me understand why.

user91187 — Wed, 16 Feb 2022 15:00:44 GMT

Hi,

What version of NCS are you on?

Regards,
Jonathan