[srslte-users] New numerology in srslte

[Zhouyou Gu]

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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