Underflow/Overflow

[houshangaziziaccelleran]

Hello
Can anyone help with the following issue:
I am testing srsRAN with n310 in FDD/n3/20MHz/2X2 and when I have:

  nof_antennas_dl: 1
  nof_antennas_ul: 1

It works (obviously with lower throughput than expected.
When I have:

  nof_antennas_dl: 2
  nof_antennas_ul: 2

then I get a lot of:
gnb_1 | Late: 246; Underflow: 40; Overflow: 0;

[houshangaziziaccelleran]

Hello,

Here is a brief summary:

I am using the latest version of srsRAN with an n310 working in the n3 band.
When a single UE is connected with the following configuration:

        nof_antennas_dl: 1
        nof_antennas_ul: 1

I achieve a DL/UL throughput of approximately 90/70 Mbps.
However, when I change the configuration to:

        nof_antennas_dl: 2
        nof_antennas_ul: 2

I encounter numerous instances of underflow/overflow, and the DL/UL throughput significantly drops to around 30/50 Mbps.

Logs are big to be uploaded. Please let me know how can I share them.

Thanks
Houshang

[brendan-mcauliffe]

Hi @houshangaziziaccelleran,

Can you provide some information on the compute platform you are using? And the connecting to the USRP? Also, it would be helpful if you could show the output of lscpu.

You can read more on over/underflows here.

[houshangaziziaccelleran]

Hello

Here is the setup:

• srsRAN, the latest version
• n310, using in n3
• BW = 20 MHz
• Cell is wired to Amarisoft's SDR card.

Here is the test:

• Attach 1 UE
• Run Bi-Dir Data

Here is the observation:

When doing 1X1, meaning we have

        nof_antennas_dl: 1
        nof_antennas_ul: 1

Then we get something around 90 mbps in the DL and something around 70 mbps in the UL.
But here is the problem: When we do 2X2 meaning we have

        nof_antennas_dl: 2
        nof_antennas_ul: 2

Then we get very low DL and very low UL (lower than the DL/UL we get for 1X1).

Please find attached lscpu printout. This is not CPU issue I think. I have 64 CPUs in my server (the server srsRAN runs on it) and I am using 32 dedicated for srsRAN.

I need to add that I am using DPDK and I have tested without DPDK as well. The results are the same.

I also need to add that with n78, I don;t have such issue. Menaing with n78, 2X2 gives higher throughput than 1X1 (as expected)

lscpu.txt

[pgawlowicz]

hi @houshangaziziaccelleran, any update on this issue? could you share your configs and gnb logs? how do you connect your usrp? do you use 10Gb Ethernet?