[srslte-users] Ouput power USRP-2901

Tue Apr 20 13:42:20 UTC 2021

Hello Taillefer Simon:

In terms of achieving the normal output power range of the B210, using UHD
3.15 should be fine.

--Neel Pandeya

On Tue, 20 Apr 2021 at 08:38, Robert Falkenberg <
robert.falkenberg at tu-dortmund.de> wrote:

> Hi Simon,
>
> just a few hints from my side:
> According to your description and the photo you posted, the actual
> transmission power of the USRP in your setup may be higher than -60dBm
> (peak value of the yellow graph), as the graph shows the gathered power
> within the Resolution Bandwidth (RBW) of the spectrum analyzer when
> sweeping over the spectrum.
> For a wideband signal, make sure you integrate the power over the whole
> signal bandwidth, e.g. https://www.youtube.com/watch?v=hSPqw4_ByNI or
> https://www.youtube.com/watch?v=t2tEYoGbHZc
>
> Furthermore, the zig-zag shape (within the signal bandwidth) may be an
> indication for a measurement in an empty cell with almost no RB/RE
> occupation except for the reference signals + PSS/SSS + sporadic
> allocations for SIBs.
> Maybe you could try a measurement with full RB allocation, e.g. attach a
> UE and transmit data during measurement.
>
> Best regards
> Robert
>
>
> Am 09.04.21 um 17:31 schrieb Taillefer Simon:
>
> Hello Neel Pandeya,
>
>
> Thank you for your answer. If we can have an output power of +10dBm as
> indicated, it will be more than expected in our case.
>
>
> We measured the output power with a spectrum analyzer. By adding amplifier
> and pre-amplifier, we can increase the output power by 50dBm but that is
> not normal that we can only achieve -60dBm with the USRP alone. Also we
> would like to not use additional equipment.
>
> Please find attached the results on the spectrum analyzer. In yellow the
> output power with a USRP alone and in blue with amplifiers added.
>
>
> We are using UHD 3.15. Do you think there could be bad behaviors by using
> this version instead of the 3.9?
>
>
> Thank you,
>
>
> Simon
> ------------------------------
> *De :* Neel Pandeya <neel.pandeya at ettus.com> <neel.pandeya at ettus.com>
> *Envoyé :* vendredi 9 avril 2021 15:00:09
> *À :* Francisco Paisana
> *Cc :* Taillefer Simon; srslte-users at lists.softwareradiosystems.com
> *Objet :* Re: [srslte-users] Ouput power USRP-2901
>
> Hello Taillefer Simon:
>
> The maximum output power for the USRP B200/B210 is approximately
> between +10 and +18 dBm, depending on frequency and gain setting.
>
> How exactly are you measuring the output power of your USRP B210?
>
> Which version of UHD are you using?
>
> https://kb.ettus.com/B200/B210/B200mini/B205mini
>
> --Neel Pandeya
>
>
>
>
> On Fri, 9 Apr 2021 at 07:21, Francisco Paisana <
> francisco.paisana at softwareradiosystems.com> wrote:
>
>> Hey,
>>
>> Regarding the MCS, I believe you can either set a maximum MCS or a fixed
>> MCS in the enb.conf. See the parameters "pdsch_mcs", "pdsch_max_mcs",
>> "pusch_mcs", "pusch_max_mcs".
>>
>> For the bandwidth, I don't think that changing a UE's DL grant bandwidth
>> will affect the maximum DL tx power. For the UL, our eNB will only support
>> UL power control and PHR handling in the upcoming release, so changing the
>> bandwidth will not have a noticeable impact, I believe.
>>
>> With regard to the USRP tx power, maybe some other users on the mailing
>> list can help.
>>
>> Kind Regards,
>> Francisco
>>
>>
>> On Fri, Apr 9, 2021 at 11:35 AM Taillefer Simon <
>> simon.taillefer at telespazio.com> wrote:
>>
>>> Hello srsLTE team,
>>>
>>>
>>> We are encountering an issue regarding the ouput power of the SDRs we
>>> are using between the ENB and the UE.
>>>
>>>
>>> We are using 2 laptops with 2 USRP-2901 from National Instrument on what
>>> we flash the firmware of the USRP B210 when running srsENB and srsUE using
>>> UHD.
>>>
>>>
>>> The maximum output power from the NI documentations is +15dBm but in our
>>> case, the maximum output power we can achieve is around -60dBm that allow
>>> us to have around 10 meters of range between the two USRPs. In the conf
>>> files. the TX and RX gains are already at the maximum value (respectively
>>> 89 and 40 dB).
>>>
>>> So do you know how we can manage to have more output power from our
>>> USRPs? Is there a limit in the code of file conf that does not allow the
>>> USRPs to work at their maximum output power? Our goal is to achieve at
>>> least -30dBm.
>>>
>>> Also, how can we set the modulation to only BPSK or QPSK instead of QAM?
>>> We saw that it is maybe possible to fix the MCS index? And can we decrease
>>> the bandwidth to maybe have more power?
>>>
>>> Thank you for your help,
>>>
>>> Simon Taillefer
>>>
>>>
>>>
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