[srslte-users] MIMO and srsUE

[Ismael Gomez]

There seem to be buffer overflows in the USRP. That's a sign that the CPU
can't keep up with the processing. You can see in the ue.log a few Warning
Overflow.

Since you are doing 2x2 at 20 MHz, which is the most demanding
configuration, you need to make sure that:

- You have a powerful enough CPU, i7 quad-core 3 GHz at least
- set expert.nof_phy_threads=3 in ue.conf to run 3 threads for the PHY
- set rf.device_args = "otw_format=sc12" to use 12-bit over-the-wire format
for the USRP







On Thu, 19 Oct 2017 at 17:48 Andrés García Saavedra <
andres.garcia.saavedra at gmail.com> wrote:

> Hi,
>
> Yes, sorry forgot to mention, yes, we did set nof_rx_antennas=2 in the
> ue.conf.
>
> Andres
>
> On Thu, Oct 19, 2017 at 3:21 PM, Ismael Gomez <
> ismael.gomez at softwareradiosystems.com> wrote:
>
>> Hi Andres,
>>
>> Have you set nof_rx_antennas=2 in the ue.conf?
>>
>> On Thu, 19 Oct 2017 at 16:51 Andrés García Saavedra <
>> andres.garcia.saavedra at gmail.com> wrote:
>>
>>> Hi all,
>>>
>>> We are trying to test the 2x2 MIMO setup of srsUE and we are having
>>> issues.
>>>
>>> We are using the latest code from the git repository (up to today). We
>>> are using an USRP b210 for srsUE and a commercial LTE base station from
>>> spidercloud Wireless. We are using plain air in band 7 (which we have a
>>> licensed for).
>>>
>>> If we plug in 2 antennas on one RF Chain A of the USRP the attachment
>>> works well and we achieve around 70Mb/s of downlink throughput as expected
>>> for a SISO setup. UE log can be found here
>>> <https://www.dropbox.com/s/xttw1s8wg4pkg7l/ue-1RX%20antenna.log?dl=0>
>>> (there is an error notifying that TM 3 is not supported by the UE which is
>>> expected as we dont have antennas on the RF chain B).
>>>
>>> If we now add 2 more antennas to RF Chain B and repeat the process we
>>> have plenty of "Sync error. Sending out-of-sync to RRC" messages and
>>> therefore the attachment procedure fails, as shown in the ue.log file
>>> here
>>> <https://www.dropbox.com/s/d7xutmasglirk22/ue-2RX%20antenna.log?dl=0>.
>>>
>>> Somebody has experienced a similar problem or have some suggestion?
>>>
>>> Thanks!
>>> Andres
>>> _______________________________________________
>>> srslte-users mailing list
>>> srslte-users at lists.softwareradiosystems.com
>>> http://www.softwareradiosystems.com/mailman/listinfo/srslte-users
>>>
>>
>
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