nrscan does not find any cell

[GinesGarcia]

Dear developers,
I would like to first thank you for releasing this amazing tool to the community.

While testing your application, I noticed that nrscan never finds an SA cell. Could you provide some information about how to solve this issue?

I'm using a very simple setup with a 16-core CPU and a USRP B210 (the same problem appears with N310).

Regards,
Ginés.

[XuyangCaoPrinceton]

Dear Ginés,

May I know what does your config.yaml in build/nrscope/src look like? What's the rx_gain value you set?

Indeed, it's not very easy to hear commercial SA cells if they are relatively distant and with an usrp indoor. Could you:

• double check the USRP/antenna is at a good location (maybe put close to window)?
• ensure the antenna is connected to the right USRP port (e.g., when nrscan running, the port gets used will flash green light)?
• change nof_trials_scan = 200; to maybe 1000 or more in radio_nr.cc, so scanning at each GSCN point will be repeated more times.

Also, there is a chance there is indeed no SA cell nearby. Something like www.cellmapper.net or Cellular-Pro app could serve as a cross validation.

Sincerely,

Xuyang

[GinesGarcia]

Hi Xuyang,
I'm currently using the default configuration (rx_gain = 75) but I also tried with 80 with no luck.

Thanks a lot for your suggestions. I'm building an ad-hoc SA cell to test the nrscann functionality but the signal may indeed be not strong enough. I'll test it again with an increased tx_power and nof_trials and post the result here.

Thanks a lot!

Regards,
Ginés.

[XuyangCaoPrinceton]

Hi Ginés,

I see. rx_gain = 75 looks good to me. Yep not sure if the tx_gain of your ad-hoc SA cell is strong enough. What nrscan does is essentially trying SSB detection on all possible GSCN points. Given if you know the SSB frequency of your ad-hoc SA cell, you could just enter that in build/nrscope/src/config.yaml (e.g., ssb_freq: 622850000) and run nrscope instead. nrscope will just directly try that single GSCN point. If nrscope could easily detect the SSB, then should nrscan as well.

Sincerely,

Xuyang

[XuyangCaoPrinceton]

We also add a FAQ page if helps: https://github.com/PrincetonUniversity/NR-Scope/wiki/7.-Usage-Recommendations-and-FAQ

[GinesGarcia]

Hi Xuyang,
thanks a lot for your help!!

We are still facing the same issue. Actually, a cell that is correctly identified by nrscope, is not being discovered by nrscan.

Regards,
Ginés.

[XuyangCaoPrinceton]

Hi Ginés,

I see. Could you share the SSB frequency and SCS of your cell? There might be some logical error in my code, and I will check. Many thanks!

Also may I know if nrscope can find the cell/detect the ssb every time you run? If no error, the probability nrscope and nrscan find the cell should be the same, but nrscan takes a long time for all the scanning, so it's indeed cumbersome to try and try again.

Sincerely,

Xuyang