[srslte-users] Measuring latency

[Kewin Rausch]

Hi Steffen,

Have you considered using the TTI as tick counter? The signal must be
coherent or otherwise the two devices cannot keep the connection enabled.
If the PCs have no such precise counter, why not using the signal itself
(which means using usrp hw)?

i.e: if 300 TTI are counted, then 300 milliseconds elapsed.

Be careful that this is not always a good solution to use; depends on what
are you trying to do!

Cheers,
Kewin R.

On Wed, Oct 31, 2018, 7:55 PM Steffen Heber <hopeless.heber at gmail.com>
wrote:

> Hi Andre and Kewin,
>
> Thank you for your suggestions.
>
> @Andre: Can you please give me any pointers for increasing the grant size
> of enodeb?
> @Kewin: As soon as I sync the time (i.e., get the time from internet), I
> found the hour, minute, and second same across two machines. However, after
> a certain time interval, there is a time drift (in millisecond range)
> between two machines.
>
>
> Thanks,
> Steffen
>
>
>
> On Wed, Oct 31, 2018 at 6:04 AM Kewin Rausch <krausch at fbk.eu> wrote:
>
>> Hi Hopeless Heber, :-D
>>
>> did you check that the time stamps are fine? I mean, are the machine
>> synced with times? Small differences can impact the computation.
>> So maybe receiver and transmitter are doing their tasks, but since the
>> timing does not have a common base (not synchronized), the final delta is
>> wrong.
>>
>> Cheers,
>> Kewin R.
>>
>> On Wed, Oct 31, 2018 at 10:56 AM Steffen Heber <hopeless.heber at gmail.com>
>> wrote:
>>
>>>
>>> I have added a couple of new fileds in one of RRC layer meassges and
>>> wanted to measure the end-to-end transmission delay/latency of that message
>>> because of additional fields. To achieve that I did the following: synced
>>> the time of sender and the receiver machines to the local timezone; used
>>> gettimeofday function to find the timestamps of message transmission (t1)
>>> and reception (t2) at the sender and the receiver; the transmission
>>> timestamp (t1) was included in the message so that the receiver can compute
>>> the latency, i.e., delta=t2-t1. Unfortunately, I always found delta less
>>> than 0 ms.
>>>
>>> Could anyone please give me any pointers to what I am doing wrong or a
>>> better way to compute the latency of the message?
>>>
>>> Thanks,
>>> Steffen
>>> _______________________________________________
>>> srslte-users mailing list
>>> srslte-users at lists.softwareradiosystems.com
>>> http://www.softwareradiosystems.com/mailman/listinfo/srslte-users
>>>
>>
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-- 
--
Le informazioni contenute nella presente comunicazione sono di natura 
privata e come tali sono da considerarsi riservate ed indirizzate 
esclusivamente ai destinatari indicati e per le finalità strettamente 
legate al relativo contenuto. Se avete ricevuto questo messaggio per 
errore, vi preghiamo di eliminarlo e di inviare una comunicazione 
all’indirizzo e-mail del mittente.

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intended only for the person or entity to which it is addressed and may 
contain confidential and/or privileged material. If you received this in 
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