[srsran-users] external clock for UE needed?

[Brendan McAuliffe]

Hi,

It is recommended to use an external clock for the eNB/gNB when connecting
to a COTS UE. The issue comes from the CFOs and timings tolerated by 5G
handsets - the onboard clocks within SDRs are not always accurate enough to
operate within the limits allowed by the handsets. Using an external clock,
which is much more accurate than an SDR onboard clock, reduces the
likelihood that a COTS UE will be unable to see/ connect to the network due
to synchronization issues.

The clocks in 5G COTS UEs are highly accurate, so it is not necessary to
externally clock the device. Although, if you were using a soft UE and an
SDR to connect to the eNB/gNB, then it would be beneficial to clock this
similarly to the eNB/gNB.

As a side note, any questions relating to srsRAN Project should go on
the discussions
board <https://github.com/srsran/srsRAN_Project/discussions>, it OK to
continue to use this list for srsRAN 4G related questions.

Best regards,
Brendan


On Mon, 6 Mar 2023 at 12:53, oiu13q2t5pibtq1 <oiu13q2t5pibtq1 at proton.me>
wrote:

>
> https://docs.srsran.com/projects/project/en/latest/user_manuals/source/1_getting_started.html
> states:
>
> > If you plan to connect the gNB to a COTS UE we recommend that you use an
> external clock source such as an Octoclock of GPSDO that is compatible with
> your RF-frontend, as the on-board clock within the USRP is not accurate
> enough to enable a connection with the UE. This is discussed further in the
> relevant app note.
> And here:
> https://docs.srsran.com/projects/4g/en/latest/app_notes/source/5g_sa_COTS/source/index.html
> its stated:
>
> > If you encounter issues with the phone not finding the cell and/or not
> being able to stay connected it might be due to inaccurate clocks at the
> gNBs RF frontend. Try to use an external 10 MHz reference or use a
> GPSDO-disciplined oscillator.
>
>
>
> So do I only need an external clock for eNB/gNB nodes or would I also use
> one for UE operations?
>
> _______________________________________________
> srsran-users mailing list
> srsran-users at lists.srsran.com
> https://lists.srsran.com/mailman/listinfo/srsran-users
>


-- 
Brendan McAuliffe

User Success Associate

Software Radio Systems, Ltd.
brendan at srs.io
www.srs.io
Barcelona, Spain
[image: twitter] <https://twitter.com/Brendan_SRS>
[image: linkedin] <https://www.linkedin.com/in/bmcaulif/>
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