[srslte-users] Frequency offsets in srsUE
Philip Shaw
philip at surewavetechnology.co.uk
Mon Aug 30 12:17:10 UTC 2021
Hi
Thank you for this, so if I set, say, 1mhz offset in srsUE config file, you don't believe if will work?
Many thanks
Philip
Sent from my Galaxy
-------- Original message --------
From: Andre Puschmann <andre at srs.io>
Date: 30/08/2021 09:54 (GMT+00:00)
To: Philip Shaw <philip at surewavetechnology.co.uk>, Xavier Arteaga <xavier at srs.io>
Cc: srslte-users at lists.softwareradiosystems.com
Subject: Re: [srslte-users] Frequency offsets in srsUE
Hey,
On 24/8/21 15:20, Philip Shaw wrote:
> I can set an offset using the property in the config file. I can see
> that the search for a cell is now at this offset frequency in the
> baseband (at the analogue signal point on the interface between the
> UBX160 and X300)
>
> Will srsUE handle this?
Yes, srsUE will compensate any fractional CFO of up to half the
subcarrier-spacing, i.e. for LTE this is 15khz/2=7.5kHz
Thanks
Andre
>
> Regards
>
> Philip
>
> *From:*Xavier Arteaga <xavier at srs.io>
> *Sent:* 24 August 2021 14:15
> *To:* Philip Shaw <philip at surewavetechnology.co.uk>
> *Cc:* srslte-users at lists.softwareradiosystems.com
> *Subject:* Re: [srslte-users] Frequency offsets in srsUE
>
> Hi Philip,
>
> What about using custom frequencies?
>
> You can set the srsenb and srsue to operate in any frequency
> independently of the EARFCN.
>
> For the UE:
>
> --rat.eutra.dl_freq arg (=-1) Downlink Frequency (if
> positive overrides EARFCN)
> --rat.eutra.ul_freq arg (=-1) Uplink Frequency (if positive
> overrides EARFCN)
>
> For the eNb:
>
> --rf.dl_freq arg (=-1) Downlink Frequency (if
> positive overrides EARFCN)
> --rf.ul_freq arg (=-1) Uplink Frequency (if positive
> overrides EARFCN)
>
> Regards,
>
> Xavier
>
> On Tue, 24 Aug 2021 at 15:06, Philip Shaw
> <philip at surewavetechnology.co.uk
> <mailto:philip at surewavetechnology.co.uk>> wrote:
>
> Xavier,
>
> We are adding some analogue hardware that has a lower frequency cut
> off. It does not work to DC.
>
> The idea is to move the Baseband signal away from zero Hz.
>
> I hope this helps.
>
> Regards
>
> Philip
>
> *From:*Xavier Arteaga <xavier at srs.io <mailto:xavier at srs.io>>
> *Sent:* 24 August 2021 13:06
> *To:* Philip Shaw <philip at surewavetechnology.co.uk
> <mailto:philip at surewavetechnology.co.uk>>
> *Cc:* srslte-users at lists.softwareradiosystems.com
> <mailto:srslte-users at lists.softwareradiosystems.com>
> *Subject:* Re: [srslte-users] Frequency offsets in srsUE
>
> Hi Philip,
>
> I guess you are asking how to avoid carrier leakage
> <https://en.wikipedia.org/wiki/Carrier_wave#Carrier_leakage>. If so,
> this email will answer your question.
>
> There are a few advanced no documented `device_args` parameters that
> can do this function.
>
> You can use the parameter `lo_freq_offset_hz` implemented here
> <https://github.com/srsran/srsRAN/blob/master/lib/src/phy/rf/rf_uhd_generic.h#L175>.
> To set the local oscillator frequency out of the band of interest
> and avoid carrier leakage.
>
> When tuning the LO with X300, there is a tune request
> <https://github.com/srsran/srsRAN/blob/master/lib/src/phy/rf/rf_uhd_generic.h#L368>.
> This provides a target RF frequency and other two frequencies: LO
> frequency and DDC/DUC intermediate frequency.
>
> By setting `lo_freq_offset_hz` the LO frequency is moved
> `lo_freq_offset_hz` Hz from the target frequency while the DSP
> frequency is set to an auto policy.
>
> I recommend setting `lo_freq_offset_hz` to equal the sampling rate
> (i.e. 23.04e6) to make sure it is far enough from the band of
> interest. If you are working with FDD, make sure TX LO frequency is
> not in the RX band.
>
> Regards,
>
> Xavier
>
> On Tue, 24 Aug 2021 at 13:33, Philip Shaw
> <philip at surewavetechnology.co.uk
> <mailto:philip at surewavetechnology.co.uk>> wrote:
>
> Hi,
>
> Neel said:
>
> Hello Philip:
>
> Are you basically asking how to do offset tuning with
> srsRAN/srsLTE/srsUE?
>
> I'm not sure whether this is currently supported. You should be
> able to
>
> have srsUE tune to a non-3GPP frequency band (which is basically
> the effect
>
> of using offset tuning), but I'm not sure that the srsUE PHY
> would be able
>
> to accommodate for that in its processing.
>
> --Neel Pandeya
>
> Hi Neel / Paul,
>
> I have a X300 with a UBX160. I need to move the analogue BB
> signal away from DC zero Hz before it enters the X300 for ADC
> etc. I can set an offset using the property in the config
> file. I can see that the search for a cell is now at this
> offset frequency (at the analogue signal point on the interface
> between the UBX160 and X300). I don’t have a cell to connect to
> (for testing), so the question is will srsUE connect to a cell
> using a large offset value?
>
> A offset of 1Mhz would be perfect for what we are doing. Will
> the PHY work? So, the system knows that the received signal is
> offset from zero Hz and is able to recover it?
>
> Thank you.
>
> Philip
>
> _______________________________________________
> srslte-users mailing list
> srslte-users at lists.softwareradiosystems.com
> <mailto:srslte-users at lists.softwareradiosystems.com>
> https://lists.softwareradiosystems.com/mailman/listinfo/srslte-users
> <https://lists.softwareradiosystems.com/mailman/listinfo/srslte-users>
>
>
> _______________________________________________
> srslte-users mailing list
> srslte-users at lists.softwareradiosystems.com
> https://lists.softwareradiosystems.com/mailman/listinfo/srslte-users
>
--
Andre Puschmann
Software Radio Systems (SRS)
https://www.srs.io
andre at srs.io
PGP/GnuPG key: 0x204A85DFEA324D58
fingerprint: 3924 1C60 D52E 81A2 1F2E 0C9D 204A 85DF EA32 4D58
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.srsran.com/pipermail/srsran-users/attachments/20210830/6095f058/attachment.htm>
More information about the srsran-users
mailing list