RAI support in LTE-M and NB-IoT on nRF9151 (France operators)

[Hassan0]

Hello,

I am currently testing the Release Assistance Indication (RAI) feature on the nRF9151 (SMA-DK) in order to minimize power consumption after data transmission.

I am using the %RAI command with value 2 to enable RAI and receive network feedback about its configuration:

AT%RAI=2

The notification I receive is:

%RAI: <cell_id>,<plmn>,<as_rai_configuration>,<cp_rai_configuration>
Test setup:
Module: nRF9151 (SMA-DK)
Firmware: v2.0.x (≥2)
Networks tested in France:
Orange
Bouygues Telecom
SFR
Observed behavior:
LTE-M:

For all three operators, I consistently get:

as_rai_configuration = 0
cp_rai_configuration = 0
NB-IoT:
Bouygues Telecom and SFR:
as_rai_configuration = 0
cp_rai_configuration = 1
Question:

Does this mean that:

RAI is not supported in LTE-M by these operators in France?
Only CP-RAI is supported in NB-IoT (and not AS-RAI)?
Or could this behavior be related to:
Network configuration limitations?
SIM/operator profile restrictions?
Or specific modem/firmware constraints?
Additional context:

My goal is to reduce current consumption by allowing the network to release the connection immediately after uplink transmission using RAI.

What I’m looking for:
Clarification on RAI support (LTE-M vs NB-IoT) in European / French networks
Confirmation if this behavior is expected
Any recommendations to effectively use RAI with nRF91 series

[Syed Maysum Abbas Zaidi]

Hi,

Your setup is correct and the behavior you're seeing seems expected, as RAI feature can be used if network supports it. Actually the %RAI notification tells you what the network has configured, not what the modem is capable of.

Your results for LTE-M (all three operators) shows that AS-RAI is simply not enabled by the operator on their LTE-M cells (CP-RAI feature is not for LTE-M). This is an operator/network infrastructure decision so the device cannot force it. However for NB-IoT (Bouygues, SFR) it shows that CP-RAI is available and you can use it. Just keep AT%RAI=2 and after enabling RAI, you can control it using the nrf_setsockopt() function with the NRF_SO_RAI socket option as mentioned here.  

For LTE-M without AS-RAI, your best option for power savings is tuning PSM and eDRX. If AS-RAI on LTE-M is a hard requirement, you'd need to raise it directly with the operators, it's outside what the device can control.

Best Regard,
Syed Maysum