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free5G / free5GRAN

free5GRAN is an open-source 5G RAN stack. The current version includes a receiver which decodes MIB & SIB1 data. It also acts as a cell scanner. free5GRAN works in SA mode.
Apache License 2.0
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Scanning commercial cells #24

Open Carcalmoa opened 3 weeks ago

Carcalmoa commented 3 weeks ago

I've been trying to scan commercial cells with free5GRAN, but I've encountered some problems.

Since the only information I have about the cells is the frequency range in which they transmit, I have tried to detect them using BAND_SCAN. The problem is that I don't know the ssb_period of the cells. I have tried to use a script in which I iterate different values from 5ms to 160ms with a step of 5ms. It runs for hours, but sometimes I'm lucky and the program is able to detect them. However, the ssb_period in which the scan succeeds seems to be random as each execution of the script detects the cell with different ssb_period values. Is there a way to know the ssb_period in advance?

I have also tried the SEARCH_CELL and it works to find my own gNBs, but for commercial cells as I don't have any information about ssb_frequency, gscn or ssb_period I find it impossible.

Is there a more effective way to detect commercial cells? Or is there a way to obtain the values I need to refine my search?

Thank you very much!

johst-source commented 2 weeks ago

Correct me if I'm wrong, but can we not assume that the SSB period is 20ms during inital cell search?

Carcalmoa commented 2 weeks ago

I'm not sure about that, have you been able to detect different commercial cells without having any context information in advance, always using 20ms as the SSB period?

johst-source commented 2 weeks ago

No, am currently unable to locate any commercial cell on any band.