LTE-M Release assistance indication (RAI)

[Luuk Bosma]

The current RRC Inactivity Timer from my provider is 10 seconds, causing my power consumption in RRC Connected mode to be unnecessarily high.

I want to use the Release Assistance Indication (RAI) feature to avoid this, but can’t get it to work.

Hardware: nRF9160 SICA B0A

Software: nRF9160: Modem Shell (https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.7.0/nrf/samples/nrf9160/modem_shell/README.html)

nRF Connect SDK: 1.7.0

Modem FW version: mfw_nrf9160_1.3.0

Here you can see that I open a socket with RAI settings, and that I transmit a ping with RAI settings, but both keep RRC mode Connected for about 10 seconds.

2021-10-08 14:47:26.055 | rtt:~$ link funmode -4
2021-10-08 14:47:26.055 | PDN event: PDP context 0 deactivated
2021-10-08 14:47:26.056 | RRC mode: Connected
2021-10-08 14:47:26.056 | Network registration status: unknown
2021-10-08 14:47:26.057 | LTE cell changed: Cell ID: -1, Tracking area: -1
2021-10-08 14:47:26.058 | Currently active system mode: None
2021-10-08 14:47:27.411 | RRC mode: Idle
2021-10-08 14:47:27.624 | Functional mode set successfully: flightmode
2021-10-08 14:47:30.833 | rtt:~$ link rai -e
2021-10-08 14:47:30.833 | Release Assistance Indication functionality set to enabled=1.
2021-10-08 14:47:30.835 | The change will be applied when going to normal mode for the next time.
2021-10-08 14:47:33.377 | rtt:~$ link funmode -1
2021-10-08 14:47:33.377 | Functional mode set successfully: normal
2021-10-08 14:47:34.372 | Network registration status: searching
2021-10-08 14:47:34.373 | LTE cell changed: Cell ID: xxx, Tracking area: yyy
2021-10-08 14:47:34.374 | Currently active system mode: LTE-M
2021-10-08 14:47:34.464 | RRC mode: Connected
2021-10-08 14:47:35.659 | PDN event: PDP context 0 activated
2021-10-08 14:47:35.660 | Network registration status: Connected - roaming
2021-10-08 14:47:37.180 | Modem config for system mode: LTE-M
2021-10-08 14:47:37.181 | Modem config for LTE preference: No preference, automatically selected by the modem
2021-10-08 14:47:37.182 | Currently active system mode: LTE-M
2021-10-08 14:47:37.202 | Modem FW version:      mfw_nrf9160_1.3.0
...
2021-10-08 14:47:46.821 | RRC mode: Idle
2021-10-08 14:47:49.622 | rtt:~$ ping -r -d 8.8.8.8
2021-10-08 14:47:49.622 | Initiating ping to: 8.8.8.8
2021-10-08 14:47:49.643 | Source IP addr: xxx
2021-10-08 14:47:49.644 | Destination IP addr: 8.8.8.8
2021-10-08 14:47:49.739 | RRC mode: Connected
2021-10-08 14:47:49.885 | Pinging 8.8.8.8 results: time=0.242secs, payload sent: 0, payload received 0
2021-10-08 14:47:51.092 | Pinging 8.8.8.8 results: time=0.181secs, payload sent: 0, payload received 0
2021-10-08 14:47:52.205 | Pinging 8.8.8.8 results: time=0.113secs, payload sent: 0, payload received 0
2021-10-08 14:47:53.322 | Pinging 8.8.8.8 results: time=0.106secs, payload sent: 0, payload received 0
2021-10-08 14:47:54.319 | 
2021-10-08 14:47:54.319 | Ping statistics for 8.8.8.8:
2021-10-08 14:47:54.320 |     Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)
2021-10-08 14:47:54.321 | Approximate round trip times in milli-seconds:
2021-10-08 14:47:54.321 |     Minimum = 106ms, Maximum = 242ms, Average = 160ms
2021-10-08 14:47:54.322 | Pinging DONE
2021-10-08 14:48:04.901 | RRC mode: Idle
2021-10-08 14:48:07.228 | rtt:~$ sock connect -a xxx -p yyy
2021-10-08 14:48:07.228 | Socket open and connect family=1, type=1, port=yyy, bind_port=0, pdn_cid=0, address=xxx
2021-10-08 14:48:07.331 | RRC mode: Connected
2021-10-08 14:48:07.883 | Socket created socket_id=0, fd=4
2021-10-08 14:48:09.378 | rtt:~$ sock rai -i 0 --rai_last
2021-10-08 14:48:09.378 | Socket option SO_RAI_LAST set
2021-10-08 14:48:11.297 | rtt:~$ sock send -i 0 -d testing
2021-10-08 14:48:11.297 | Socket data send:
2021-10-08 14:48:11.298 |         testing
2021-10-08 14:48:23.067 | RRC mode: Idle

I think it has to do with the %REL14FEAT command not being accepted. It doesn’t give an error, but it always reads back as zero:

rtt:~$ at AT%REL14FEAT=1,1,1,1,1
OK
rtt:~$ at AT%REL14FEAT?
%REL14FEAT: 0,0,0,0,0
OK
rtt:~$ at AT%REL14FEAT=0,1,0,0,0
OK
rtt:~$ at AT%REL14FEAT?
%REL14FEAT: 0,0,0,0,0
OK

[Luuk Bosma]

offtopic:

The documentation at https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.7.0/nrf/samples/nrf9160/modem_shell/README.html#id5 is outdated.

sock rai --rai_enable

is now

link rai -e

[Didrik Rokhaug]

Hi,

What network do you use? Does it support RAI on LTE-M?

Could you take a modem trace?

Luuk Bosma said:

The documentation at https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.7.0/nrf/samples/nrf9160/modem_shell/README.html#id5 is outdated.

Thank you for pointing this out. I'll report this internally.

Best regards,

Didrik

[Luuk Bosma]

Here is my modem trace from a Nordic Thingy:91

/cfs-file/__key/communityserver-discussions-components-files/4/trace_2D00_2021_2D00_10_2D00_18T07_2D00_51_2D00_53.419Z.bin

[Didrik Rokhaug]

Thanks. I've sent it to the modem team, so that they can take a look at it.

I'll let you know what they find.

[Didrik Rokhaug]

One explanation for the %REL14FEAT behaviour is if the modem is using an operator configuration where the release 14 features aren't allowed.

Could you check the output of the following AT commands?

AT%XOPERID

AT%XOPCONF?

[Luuk Bosma]

All three (roaming) providers (Vodafone Netherlands, KPN B.V., T-Mobile Netherlands) report the same:

rtt:~$ at AT%XOPERID
%XOPERID: 16

OK
rtt:~$ at AT%XOPCONF?
%XOPCONF: 1

OK

Note that I do see different RRC Inactivity Timer values and massive different power consumption between these three roaming providers.

Green: Vodafone
Yellow: KPN
Red: T-Mobile

[Didrik Rokhaug]

Based on the commands, it looks like the device is using the Deutsche Telekom profile, which was detected autmatically from the SIM card.

To confirm that, we need a modem trace that captures the modem booting up, i.e. where you reset the device after starting the modem trace.

In the Deutsche Telekom profile, all release 14 features has been disabled in mfw 1.3.0, which would explain why you are not able to enable any of them.

[Didrik Rokhaug]

Could you try to update to mfw 1.3.1?

There the rel 14 features should be enabled.