RF status overflow

Question

RF status overflow

ruedagarcialaura opened this issue 4 months ago · 23 comments

Issue Description

When trying to connect the UE to the gNB it doesn't attach and gets stuck with overflow values. Sometimes the overflow is up to 150 and the best I got was overflow 1.

Setup Details

Os: Ubuntu 22.04 on 3 PCs
UE: srsRAN_4G connected via usb3 to USRP b200 mini
gNB: srsRAN_Project connected via usb3 to USRP b200
core: open5gs

Expected Behavior

UE attaches to gNB, a pdu session is established and it gets an IP address.

Something like:

Attaching UE...
Random Access Transmission: prach_occasion=0, preamble_index=0, ra-rnti=0x39, tti=2094
Random Access Complete. c-rnti=0x4602, ta=0
RRC Connected
PDU Session Establishment successful. IP: 10.45.1.2
RRC NR reconfiguration successful.

Actual Behaviour

$sudo ./srsue ue_rf.conf

AActive RF plugins: libsrsran_rf_uhd.so
Inactive RF plugins:
Reading configuration file ue_rf.conf...

Built in Release mode using commit ec29b0c1f on branch master.

Opening 1 channels in RF device=uhd with args=default
Supported RF device list: UHD file
[INFO] [UHD] linux; GNU C++ version 11.2.0; Boost_107400; UHD_4.1.0.5-3
[INFO] [LOGGING] Fastpath logging disabled at runtime.
Opening USRP channels=1, args: type=b200,master_clock_rate=23.04e6
[INFO] [UHD RF] RF UHD Generic instance constructed
[INFO] [B200] Detected Device: B200mini
[INFO] [B200] Operating over USB 3.
[INFO] [B200] Initialize CODEC control...
[INFO] [B200] Initialize Radio control...
[INFO] [B200] Performing register loopback test...
[INFO] [B200] Register loopback test passed
[INFO] [B200] Asking for clock rate 23.040000 MHz...
[INFO] [B200] Actually got clock rate 23.040000 MHz.
Setting manual TX/RX offset to 300 samples
Waiting PHY to initialize ... done!
Attaching UE...
RF status: O=1, U=0, L=0

Steps to reproduce the problem

I have already set the CPU governor to performance in both the gNB computer and the UE computer.
I have checked if the overflow problem has to do with the CPU but it is free/inactive most of the time
$mpstat
Linux 6.5.0-28-generic (tueilkn-ue) 02.05.2024 x86_64 (4 CPU)

16:35:57 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle
16:35:57 all 0,94 0,01 0,75 0,03 0,00 0,01 0,00 0,00 0,00 98,25

I have verify the USRP is correctly configured by running sudo ./benchmark_rate --rx_rate 23.04e6 --tx_rate 23.04e6 and this is the result I get:
Benchmark rate summary:
Num received samples: 236706097
Num dropped samples: 0
Num overruns detected: 0
Num transmitted samples: 236213640
Num sequence errors (Tx): 0
Num sequence errors (Rx): 0
Num underruns detected: 0
Num late commands: 0
Num timeouts (Tx): 0
Num timeouts (Rx): 0

Additional Information

The gNB and core are connected and seem to work fine

The PRACH detector will not meet the performance requirements with the configuration {Format 0, ZCZ 0, SCS 1.25kHz, Rx ports 1}.
srsLog error - Unable to create log file "/tmp/gnb.log": Permission denied
Lower PHY in quad executor mode.

--== srsRAN gNB (commit 2f90c8b) ==--

Connecting to AMF on 10.162.149.143:38412
Available radio types: uhd.
[INFO] [UHD] linux; GNU C++ version 11.2.0; Boost_107400; UHD_4.1.0.5-3
Making USRP object with args 'type=b200'
[INFO] [LOGGING] Fastpath logging disabled at runtime.
[INFO] [B200] Detected Device: B210
[INFO] [B200] Operating over USB 3.
[INFO] [B200] Initialize CODEC control...
[INFO] [B200] Initialize Radio control...
[INFO] [B200] Performing register loopback test...
[INFO] [B200] Register loopback test passed
[INFO] [B200] Performing register loopback test...
[INFO] [B200] Register loopback test passed
[INFO] [B200] Setting master clock rate selection to 'automatic'.
[INFO] [B200] Asking for clock rate 16.000000 MHz...
[INFO] [B200] Actually got clock rate 16.000000 MHz.
[INFO] [MULTI_USRP] Setting master clock rate selection to 'manual'.
[INFO] [B200] Asking for clock rate 23.040000 MHz...
[INFO] [B200] Actually got clock rate 23.040000 MHz.
Cell pci=1, bw=20 MHz, dl_arfcn=368500 (n3), dl_freq=1842.5 MHz, dl_ssb_arfcn=368410, ul_freq=1747.5 MHz

==== gNodeB started ===
Type to view trace

Answer 1 · 2024-05-02T15:28:56.000Z

Could you check CPU usage on the srsUE host PC? with htop.
Could you run the srsran_performance on the srsUE host PC?

Answer 2 · 2024-05-03T10:18:30.000Z

@pgawlowicz Thank you for your answer. If I run htop on the gNodeB host computer I get 1.77 1.72 1.62 load average values, and the process that is currently consuming the most resources is the gNB with CPU% 107.
By running it on the UE host computer I get that the load average is 0.30 0.26 0.21 and the most consuming process has CPU% 30.

And I had already set the CPU governor to performance in the UE host computer both by doing echo "performance" | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor and by running the srsran_performance file.

Answer 3 · 2024-05-13T09:16:12.000Z

hi @ruedagarcialaura, any updates on this issue?

Answer 4 · 2024-05-13T09:41:30.000Z

Hi, I changed the GNB channel bandwith to 10 MHz and nof_prb to 52 and I don't get overflows or underflows most of the times. But it is still stuck in Attaching UE...
Here are my config files
ue_rf1.conf.txt
gnb_rf_b210_fdd.txt

And also I get this in the ue log everytime:

2024-05-13T09:33:21.847132 [PHY-SA ] [I] [ 0] SYNC: The SFN sync reached the maximum number of trials (100). Transitioning to IDLE...
2024-05-13T09:33:21.847139 [PHY-SA ] [I] [ 0] Cell Select: Could not synchronize SFN
2024-05-13T09:33:21.847234 [RRC-NR ] [E] Proc "Cell Selection" - Couldn't select new serving cell
2024-05-13T09:33:21.847235 [RRC-NR ] [I] Proc "Cell Selection" - Completed with failure.
2024-05-13T09:33:21.847241 [RRC-NR ] [W] Could not finish setup request. Deallocating dedicatedInfoNAS PDU

Here is the log:
ue3.log

Answer 5 · 2024-05-14T10:01:43.000Z

Could you try to tune TX and RX gains? It seems that the srsUE was not even able to detect the cell

Answer 6 · 2024-05-21T14:28:15.000Z

I've been trying different gain combinations in steps of 5 for different channel bandwidths (5,10,15 and 20 MHz) and no successful results, still stuck in attaching ue... Any recommendation? Thank you in advance

Answer 7 · 2024-05-21T14:31:28.000Z

could you try with an external clock?

Answer 8 · 2024-05-22T14:58:50.000Z

I am trying with the external clock Leo Bdonar GPSDO but it doesn't seem to work.
Here is my config and log of the ue.
ue_external_clock.zip

Answer 9 · 2024-05-22T15:01:30.000Z

could you share also gnb config?

Answer 10 · 2024-05-22T16:16:21.000Z

gnb config file
gnb_rf_b210_fdd.txt

Answer 11 · 2024-05-23T08:04:14.000Z

could you try the default configs from the tutorial with 10mhz bandwidth?

Answer 12 · 2024-05-24T09:47:04.000Z

tutorial_10Mhz_external_clock.zip
Here it is, it doesn't seem to use the external clock source. But the leo bodnar gpsdo has the two leds on and it's connected to both usrps.

Answer 13 · 2024-05-24T09:56:58.000Z

hi, you have to add clock parameter to your config:

ru_sdr: 
  clock: external

Answer 14 · 2024-05-24T10:13:12.000Z

tutorial_10MHz_2.zip
I changed it but it looks the results are the same

Answer 15 · 2024-05-24T10:16:35.000Z

could you change sync to default. What is the spec of the UE PC (cpu, and memory)?

Answer 16 · 2024-05-24T10:41:18.000Z

tutorial_10MHz_3.zip
I got the same result with sync: default

Answer 17 · 2024-05-24T10:45:41.000Z

hmm, strange, the setup runs over the air or RF cables? did you try to tune TX/RX gains?

Answer 18 · 2024-05-24T10:54:38.000Z

Over the air.
I tried with cable one day and the UE didn't find the cell either.
I also tried the ueransim and at least I know the core works fine.

And I have been trying different gain combinations but always get similar results of overflows and doesn't go further than attaching UE...
is there any tip to tune the gains? should the UE tx gain be higher than the gnb gains or maybe the other way around?

And also do the srates necessarily need to be the same for both usrps or can the UE work in a lower srate?

Thank you for all your responses