Using the nRF9160 on the Verizon network we are having some issues with eDRX. Specifically sending data to the device from our MQTT server.
We have configured a eDRX interval of 40.96 seconds with a PTW of 1.28 seconds. What I'm seeing is that the socket from the device to the server remains open and we can send data in that direction with no issue. Server initiated messages are not reliably delivered, and when a server messages is not delivered it s breaks the server to device connection so any subsequent MQTT publishes from the device do reach the server, but the ACK does not reach the device. If we close/open the socket then communications resume.
We tried increasing the PTW to 5.12 seconds and that seems to improve things somewhat, but we are still seeing the same issue.
Also I'm finding that if a server message is initiated during or right after a eDRX cycle, on the following eDRX cycle the nRF9160 does wake up for the ~9second RRC timeout (as seen on a current meter), but the message is not received and the socket from the server to the device is broken.
We are working with Verizon on this issue as well, but they are indicating that this may be a nRF9160 issue.
Any feedback on this use case/configuration?
Hi Josh,Please state which modem firmware version and SIM card you are using.
Please take a modemtrace so we could investigate the issue in more detail.
trace-2019-11-11T18-11-06.562Z-edrx rx ok.bintrace-2019-11-11T17-02-28.824Z-edrx rx issue.bin
Attached are two trace files. One with showing the receive issue and one showing a successful eDRX receive.
We are running modem firmware version 1.0.1
Verizon is attempting to do a packet trace on their end as well and I'll update this with any information I receive.
Hi Josh,Could you please verify the modem firmware version? (the logs cannot be decoded, most likely because of wrong modem firmware version)e.g. run at:_client (at_client.hex) with LTE Link Monitor and send the command AT+CGMR:
I did confirm that on the device I captured the logs on the reported modem firmware is mfw_nrf9160_1.0.1
I will attempt to run the captures again today and see if they work for you. Not sure why these would be invalid.
Yes, that would be great. Are you taking the modem traces from the nRF91DK or a custom board?
from the VCOM or external UART with an FTDI cable?
The issue could be the UART.
If you are using the lte_lc.c driver, it should be sufficient to put:
in the prj.conf file of your application.