RAI and Sockets

[allard.p]

I'm testing a simple application based on the UDP example.  It samples some peripherals and ADC channels, these values are then packed into a CoAP message. This CoAP message is sent trough the socket api, and the application waits for a response:

1. Create CoAP message
2. Send CoAP message using send(), no flags
3. Use poll() to poll for response
4. recv() when poll indicated there is something to read
5. repeat after a couple of seconds

This works fine with RAI disabled, but the power draw is to high, the response usually comes after 1-2 seconds, and with the network RCC timeout of 10 seconds a lot of time is wasted waiting for nothing. Now I want to enable RAI, I came across several options:

• Use 

  lte_lc_rai_param_set("3");
  lte_lc_rai_req(true);

• Use AT%RAI
• Use AT%XRAI
• Use 

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

Which one to use? I'm using modem FW 1.3.1 and sdk 1.7.0, all on NB-IOT.

[Achim Kraus]

I use

prj.conf:

CONFIG_UDP_RAI_ENABLE=y
CONFIG_LTE_RAI_REQ_VALUE="3"

and in the code

lte_lc_rai_req(true) or lte_lc_rai_req(false)

For me that works quite well.

There is also an other question about RAI with a more elaborated answer.

[allard.p]

I got RAI working using the first option, but I wonder if I can also use the setsockopt version, because this will allow me to bind the RAI to specific sockets. Using lte_lc_rai_req(true); and lte_lc_rai_req(false); around socket send() is possible, bur prone to error because you can't control when a packet is sent trough the modem.  I tried adding the setsockopt but it does nothing, does this only work with rel 14/NB-IOT2 RAI?

[Hakon]

allard.p said:

I got RAI working using the first option, but I wonder if I can also use the setsockopt version, because this will allow me to bind the RAI to specific sockets.

If you want to use the %RAI command, then you need to combine it with the socket option. You can test that, but I'm not 100% sure if this will work on rel 13.