Pixel 6 won't connect to gnb

[ffxxcad]

Hello everyone,

I've seen on this discussion board that people have had success connecting Google Pixel 6 phones using N78 at 40 Mhz. However we have not had any success in the pixel 6 connecting to the gnb despite using similar configuration settings.

The issue

The phone can see the network (shows up as 00101), but cannot join it:

Network Signal Guru sees the network as well:

I've double checked that the subscriber has been added in Open5GS and that the APN settings match that of the core:

Any thoughts of what might be going wrong?

Setup

• Ettus USRP B210
• National Instruments CDA 2990
• Google Pixel 6 (rooted)
• Gialer Programable Sim Card
• Open5GS Core

Files

gnb_GP6.zip
gNB_mac.zip
gNB_ngap.zip
amf_log.txt
gNB_log.txt

[robertfalkenberg]

It could be a performance issue. In the gNB.log, I see some warnings like

2023-07-26T19:17:39.060131 [GNB     ] [W] CPU19 scaling governor is not set to performance, which may hinder performance. You can set it to performance using the "srsran_performance" script
2023-07-26T19:17:39.060137 [GNB     ] [W] DRM KMS polling is enabled, which may hinder performance. You can disable it using the "srsran_performance" script
...
2023-07-26T19:18:27.706197 [FAPI    ] [W] [     0.0] Real-time failure in FAPI: Received late DL_TTI.request. Current slot is 705.11 while message corresponds to 705.10
2023-07-26T19:18:27.706220 [Low-PHY ] [W] Real-time failure in low-phy: Downlink data late for sector 0 and slot 704.10.
2023-07-26T19:18:27.706240 [Low-PHY ] [W] Real-time failure in low-phy: Downlink data late for sector 0 and slot 704.12.
2023-07-26T19:18:27.706449 [RF      ] [W] Real-time failure in RF: late
2023-07-26T19:18:27.706459 [RF      ] [W] Real-time failure in RF: late
2023-07-26T19:18:27.706529 [RF      ] [W] Real-time failure in RF: late
2023-07-26T19:18:27.706537 [Low-PHY ] [W] Real-time failure in low-phy: PRACH request late for sector 0, slot 705.18 and start symbol 0.
2023-07-26T19:18:27.706543 [RF      ] [W] Real-time failure in RF: late
2023-07-26T19:18:27.706549 [RF      ] [W] Real-time failure in RF: late

you could also try smaller bandwidth for the start. The device supports downto 20MHz (but not 10 MHz) in n78.

...
  srate: 23.04
...
  channel_bandwidth_MHz: 20
...

[ismagom]

Did you run the srsran_performance script?

[ffxxcad]

@ismagom & @robertfalkenberg,

Thanks for your replies.

I ran the srsran_performance script and tried out the 20 MHz but am still seeing the same behavior:

amf.zip
upf.zip

gNB_mac.zip
gNB_ngap.zip

pixel_gnb_config.zip

amf_log.txt
gNB_log.txt

I've been able to successfully connect a Oneplus8T phone on N78 and N25 so I feel confident that srsRAN is working properly. Seems like there is something going on with the phone but I can't tell what it is.

[robertfalkenberg]

Does the IMSI of the uSIM you use in the Google Pixel 6 start with 00101... as well?

[robertfalkenberg]

Here is a list of PLMN/IMSI combinations that I have tested:
#100 (reply in thread)

Please also ensure the system software is at least TQ3A.230605.010, before that it just refused to connect:
#100 (reply in thread)

[robertfalkenberg]

Here is a list of PLMN/IMSI combinations that I have tested:
#100 (reply in thread)

Please also ensure the system software is at least TQ3A.230605.010, before that it just refused to connect:
#100 (reply in thread)

[ffxxcad]

Alright so I tried updating to TQ3A.230605.010 as suggested by @robertfalkenberg above and it still didn't resolve the issue.

I also tried changing the ims settings as suggested by @robertfalkenberg here and still no luck.

I triple checked the SIM settings and noticed that the SIM I was using hadn't been completely programmed to 00101. The plmn settings in the yellow boxes below were 33102.

These values never affected the Oneplus8T phone's ability to connect so I had never updated them. After changing the plmn values to 00101 the phone was able to connect to the core and worked great on both SISO and 2x2 MIMO.

tl;dr: make sure that every instance of plmn is 00101 and it should work.

For anyone who may be interested here are the files from the successful test:
gNB_log.zip
gNB_mac.zip
gNB_ngap.zip

And the used config files:
amf.zip
gnb_GP6_Config.zip
upf.zip

Thanks again for the suggestions @robertfalkenberg, they got me on the right path.

[robertfalkenberg]

Hi @ffxxcad ,
thanks for taking the time to share your experience with the community, especially for the important note with the EF_*PLMN* fields.
Since we mostly customize our SIM cards with pySim-prog (osmocom), the mentioned fields are automatically maintained when the IMSI is changed. Of course, this does not have to be the case with other tools.