[srslte-users] New numerology in srslte

[Justin Tallon]

Hey Zhouyou,

Are you sure your processor is running in PERFORMANCE mode?

____
Justin Tallon Ph.D.

Software Radio Systems (SRS)
http://www.softwareradiosystems.com

+353-86-067-0753 | justin.tallon at softwareradiosystems.com


On Wed, Apr 1, 2020 at 12:23 PM Zhouyou Gu <guzhouyou at gmail.com> wrote:

> Thanks a lot ! Justin,
>
> Actually, I just made it working with subcarrier spacing at 30kHz,
> I made changes at the subcarrier spacing just like what you suggested.
>
> Two srsUEs can connect to the srsENB and I can ping them.
>
> Now the issue is that I found many UUULLL at srsUE
> I think it is because the TTI is shorter and the CPU is not faster enough
> to process the stack.
>
> I am wondering how can I improve this. What I am trying now is
>
>    - Try different CPU scheduling policy, e.g., SCHED_FIFO to  SCHED_RR
>    for DSP threads, Will this change help (I am not so familiar with CPU
>    scheduling)?
>    - Try allocate a fixed CPU mask for DSP.
>    - Or the only solution is to get a better CPU that can be overclocked,
>
> My CPU is @3.4Ghz and Ubuntu has been configured with a low-latency kernel.
>
> Thanks a lot!
>
> Regards,
> Zhouyou Gu
>
>
>
>
>
>
>
>
> On Wed, 1 Apr 2020 at 20:29, Justin Tallon <
> justin.tallon at softwareradiosystems.com> wrote:
>
>> Hey Zhouyou,
>>
>> If you want to play with the subcarrier spacing my advice would be to
>> pick a number of subcarriers you are happy with and then change the
>> sampling rate at which it runs.
>>
>> The easiest way this could be done is with a scaling parameter, scaling
>> the sampling rate by some factor. You will also need to change the timing
>> being sent to your RF frontend as this is passed in milliseconds, not
>> samples so this will also need to be scaled.
>>
>> In addition, pay attention to anywhere the subcarrier spacing (15000) is
>> used explicitly, especially in CFO calculations.
>>
>> Regards,
>> Justin
>> ____
>> Justin Tallon Ph.D.
>>
>> Software Radio Systems (SRS)
>> http://www.softwareradiosystems.com
>>
>> +353-86-067-0753 | justin.tallon at softwareradiosystems.com
>>
>>
>> On Tue, Mar 31, 2020 at 5:24 PM Zhouyou Gu <guzhouyou at gmail.com> wrote:
>>
>>> Dear srsLTE team,
>>>
>>> I am trying to implement a shorter TTI in srsLTE
>>> My platform is B210 and dell computer.
>>>
>>> To implement the shorter TTI, I have changed the subcarrier spacing to
>>> 30kHz (x2 than the original) and doubled the subcarrier spacing for PRACH
>>> as well.
>>> In addition, I have changed the clock rate setting.
>>>
>>> After I did this, srsUE cannot find the cell.
>>>
>>> What do you think about this idea?
>>> Is it possible on my platform (B210).
>>>
>>> If yes, what else may also need to be changed?
>>>
>>> Thanks a lot!
>>>
>>> Regards,
>>> Zhouyou
>>>
>>> _______________________________________________
>>> srslte-users mailing list
>>> srslte-users at lists.softwareradiosystems.com
>>> http://www.softwareradiosystems.com/mailman/listinfo/srslte-users
>>>
>>
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