Success using NB-S1 with control plane optimization

Hello everybody!

I’m in problematic situation where I can’t understand if my communication errors are due to network provider or due to modem. It would be helpful if others could comment on their success using NB-S1 with their operators. Maybe I can understand better from your examples.

My network operator supports only NB-S1 and only control plane optimization. I’m trying to send UDP packets to my test server. This test was performed with HL7800 using eval board.

I can create UDP socket and send one packet, but then next packets are lost. Then about 10s from first packet, I can send one more. There seems to be 10s ignored interval between packets. What is interesting, that 10s is exactly the period before my operator releases RRC due to inactivity. Looks like it is somehow connected.

Also I have done same tests on other two brands of NB modems and on has the same problem, but other doesn’t loose packets only delays them for up to 10s.

I would like to hear if others can send UDP packets using NB without these kind of problems one by one with small intervals. Especially if using control plane optimization.

Hi Janis_sk,

I can send UDP packet and no lost in remote side. No 10s limitaion my side.
Please make sure no limitation from the remote UDP app.

Here’s my log:

Remote UDP app received all the packet:
15:50:24 AAAAA
15:50:31 AAAAA
15:50:37 AAAAA

15:50:14.112 on 20-Aug-2019> AT+KUDPSND=1,“xx.xx.xx.xx”,5021,5
15:50:18.782 on 20-Aug-2019>
15:50:18.798 on 20-Aug-2019> CONNECT
15:50:18.799 on 20-Aug-2019>
15:50:23.766 on 20-Aug-2019> OK
15:50:23.769 on 20-Aug-2019> AT+KUDPSND=1,“xx.xx.xx.xx”,5021,5
15:50:28.31 on 20-Aug-2019>
15:50:28.47 on 20-Aug-2019> CONNECT
15:50:28.51 on 20-Aug-2019>
15:50:30.839 on 20-Aug-2019> OK
15:50:30.842 on 20-Aug-2019> AT+KUDPSND=1,“xx.xx.xx.xx”,5021,5
15:50:33.774 on 20-Aug-2019>
15:50:33.790 on 20-Aug-2019> CONNECT
15:50:33.793 on 20-Aug-2019>
15:50:36.443 on 20-Aug-2019> OK

Thanks, @Sierra_klin2, I checked that there are no problems with UDP server and updated version
for HL7800 to

2019/05/31 22:53:05

Thats the newest I found on this forum. I’ll try to get in contact with support to get latest version.

As far as communication, looks like nothing changed for me.

@Sierra_klin2, do you now if CHINA MOBILE has user plane optimization enabled?

CHINA MOBILE supports NB-S1. But I don’t know how to check if user plane optimization enabled or disabled.

Your network operator supports only NB-S1 and only control plane optimization. Could you share your HL7800 modem log? (Set at+switracemode=LOG and save output in debug port@921600)


I’ve repeated this test, this time on other operator that I have access to now. Response is the same. (516.3 KB) at_log.txt (480 Bytes)

I see that there is a lot of binary data in log output - is there a tool I could get to decode it, could be helpful?