Possible issues with eDRX on Verizon

RE: Possible issues with eDRX on Verizon

Martin Lesund — Fri, 13 Dec 2019 13:45:43 GMT

Hi Joshua,

A suggestion for a workaround to this could be that every time the UE device (nrf91) is going to do any communication it can send an empty MQTT packet to the server on a specific topic then the server responds accordingly with the correct data so you do not lose any packets.

NOTE: With the mfw1.1.0 the introduction of the AT+CSCON command can be used to get notifications when RRC Connections are established.

RE: Possible issues with eDRX on Verizon

Joshua — Tue, 10 Dec 2019 18:06:37 GMT

I have some additional information about how the Verizon network handles server to UE data. Verizon is telling us that the network does not buffer any TCP to the UE, but they do buffer that they need to send a page to the UE. After the UE receives the page, it will establish a RRC connection, but it is up to the server to deliver a TCP packet in the RRC window.

The issue is that the TCP server does not know when the UE has been paged.

It is possible for the nRF9160 to tell out application that it has been paged? If so we could then send a message tot he server requesting data. This could be a work around for the problem.

Since we are trying to implement bidirectional MQTT data, the current implementation of eDRX by Verizon basically makes server initiated TCP data useless, unless we can figure out a way to work around this issue.

Thank you for the help.

RE: Possible issues with eDRX on Verizon

Martin Lesund — Wed, 04 Dec 2019 07:48:39 GMT

Hi Josh,

The issue seen in these logs is that the network is paging the UE (nRF91) and RRC connection gets established but the network does not send any data, just releases connection after a few seconds.

Best regards,

Martin L.

RE: Possible issues with eDRX on Verizon

Joshua — Tue, 03 Dec 2019 14:49:34 GMT

Hi Martin,

Thanks for the response. Do you have any additional details about what the traces show that I could share with the carrier to help pinpoint the issue? Any specifics you would provide would be helpful.

Thanks!

RE: Possible issues with eDRX on Verizon

Martin Lesund — Tue, 03 Dec 2019 14:46:04 GMT

Hi Josh,

I am sorry for the wait.
From analyzing the logs from the modem traces we can clearly see that the issue is on the network side.

Please please push Verizon on this, since the issue is on the Network vendor side.

Best regards,

Martin L.

RE: Possible issues with eDRX on Verizon

Joshua — Tue, 26 Nov 2019 20:04:04 GMT

Hello,

I have re-run the tests using the 1.1.0 Modem firmware with the same results.

Packet traces are attached.

During the "trace-2019-11-26T19-49-11.648Z-eDRX no PKT.bin" I saw the nRF9160 wake up for two consecutive eDRX cycles, but it failed to receive the packet. Again once this happens the connection from the server to the nRF9160 stops working until we close/re-open the socket.

The trace-2019-11-26T19-55-04.350Z-eDRX PKT received.bin" shows a packet being successfully received from the server and the socket remains functional.

Thank you,

Josh

devzone.nordicsemi.com/.../trace_2D00_2019_2D00_11_2D00_26T19_2D00_55_2D00_04.350Z_2D00_eDRX-PKT-received.bin devzone.nordicsemi.com/.../trace_2D00_2019_2D00_11_2D00_26T19_2D00_49_2D00_11.648Z_2D00_eDRX-no-PKT.bin

RE: Possible issues with eDRX on Verizon

Joshua — Mon, 25 Nov 2019 22:25:54 GMT

Thank you for the response. We will do additional testing with the 1.1.0 Modem firmware and let you know if we are still seeing this issue.

Thank you

RE: Possible issues with eDRX on Verizon

Martin Lesund — Mon, 25 Nov 2019 14:40:43 GMT

Hi Josh,

The modem firmware version 1.1.0 has been released with a lot of improvements and features.
If possible, I would recommend you to update to the latest version and see if that improves the performance.

If not, please attach the modem trace using the new modem firmware.

Best regards,
Martin L.

RE: Possible issues with eDRX on Verizon

Joshua — Tue, 19 Nov 2019 21:45:14 GMT

devzone.nordicsemi.com/.../trace_2D00_2019_2D00_11_2D00_19T21_2D00_06_2D00_32.613Z_2D00_eDRX-No-Pkt-received.bin devzone.nordicsemi.com/.../trace_2D00_2019_2D00_11_2D00_19T21_2D00_22_2D00_53.883Z_2D00_eDRX-Pkt-received-ok.bin

Attached is another pair of captures this time from the USB port on the DK. Hopefully these work.

Thank you

RE: Possible issues with eDRX on Verizon

Martin Lesund — Tue, 19 Nov 2019 12:23:20 GMT

Hi Josh,

I am sorry for the delay.

Unfortunatly the log is still invalid.

Please repeat the test on a DK so we could get a valid modem trace from that device.

Thanks,

Martin L.

RE: Possible issues with eDRX on Verizon

Joshua — Thu, 14 Nov 2019 16:13:45 GMT

devzone.nordicsemi.com/.../trace_2D00_2019_2D00_11_2D00_14T15_2D00_46_2D00_05.849Z_2D00_eDRX-issue.bin devzone.nordicsemi.com/.../trace_2D00_2019_2D00_11_2D00_14T16_2D00_05_2D00_12.839Z_2D00_eDRX-issue.bin devzone.nordicsemi.com/.../trace_2D00_2019_2D00_11_2D00_14T16_2D00_10_2D00_11.203Z_2D00_eDRX-OK.bin

Let's see if these are better. If not we can get setup to run the same capture on the nRF91DK

RE: Possible issues with eDRX on Verizon

Joshua — Thu, 14 Nov 2019 14:54:28 GMT

I was using a custom board with external UART with a FTDI cable, which we have used successfully before. But I was using a older laptop for logging this time, so I'll change that out and see if it improves things.

Thanks

RE: Possible issues with eDRX on Verizon

Martin Lesund — Thu, 14 Nov 2019 14:42:12 GMT

Hi Josh,

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:

CONFIG_BSD_LIBRARY_TRACE_ENABLED=y

in the prj.conf file of your application.

RE: Possible issues with eDRX on Verizon

Joshua — Thu, 14 Nov 2019 14:15:57 GMT

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.

RE: Possible issues with eDRX on Verizon

Martin Lesund — Thu, 14 Nov 2019 08:31:16 GMT

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 (devzone.nordicsemi.com/.../at_5F00_client.hex) with LTE Link Monitor and send the command AT+CGMR:

RE: Possible issues with eDRX on Verizon

Joshua — Mon, 11 Nov 2019 18:17:54 GMT

devzone.nordicsemi.com/.../trace_2D00_2019_2D00_11_2D00_11T18_2D00_11_2D00_06.562Z_2D00_edrx-rx-ok.bin devzone.nordicsemi.com/.../trace_2D00_2019_2D00_11_2D00_11T17_2D00_02_2D00_28.824Z_2D00_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.

Thank you

RE: Possible issues with eDRX on Verizon

Martin Lesund — Mon, 11 Nov 2019 14:04:49 GMT

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.