Release assistance indication (RAI)

[ced27]

Hi Supportteam,

i am trying to use Release Assistance Indication (RAI) to shorten the RRC-Connected using nRF9160 DK.

I'm enabling REL14FEAT with the following AT commands before LTE-connection:

   AT%REL14FEAT=0,1,0,0,0

I then created a socket and configured with the option:

err = setsockopt(sock, SOL_SOCKET, SO_RAI_NO_DATA , NULL, 0);

In my prj.conf file i set:

CONFIG_LTE_RAI_REQ_VALUE="3"

Here is how the current draw looks like:

Here is the pcap and raw trace:

Modem Trace Interaktion.pcapng

trace-2022-01-06T10-48-30.560Z.bin

Is that which i have done realistic? What are the factors to consider when using RAI?

Thanks in advance

Best regards,

Cedric

[ced27]

Hii Didrik Rokhaug,

thanks for wonderful explanation.

Just to make sure i have understood. Just let me make small recap:

For my use case, i will use %XRAI= 4 and my protocol is CoAP with DTLS. So when i send my first packet, i set the flag with %XRAI=4 and then before i send the second packet, i have to first clear the previous flag with %XRAI=0. Afterward i can send the second packet by setting the flag again and before sending the third packet, i should clear the flag again and the cycle continues. Ist that correct?

Best regards,

Cedric

[Didrik Rokhaug]

No. You only want to set the %XRAI flag before the last message you send.

If you set it earlier, you will only get unnecessary RRC connection teardowns and setups.

You should then clear the flag again before you start sending new packets.

[ced27]

Hi Didrik,

thanks for the respond.

This means i only set the flag once (before the last message i send) and before i start sending new packets, i clear the flag. Meaning after that no flag is to be set or clear again, is that correct?

Best regards,

Cedric

[Didrik Rokhaug]

For each time you send packets clear the flag first, start sending, before you send the last packet set the flag, then send the last packet.

But, as I have tried to say, the problem is that you don't know when the modem actually sends the packets on the air, so you still risk unnecessary RRC signalling.

[ced27]

Thanks very much Didrik. All these informations will really help me.

Best regards,

Cedric