Re: [6tisch] [6TISCH] Specify the number of cells to be added or deleted in SF0

Nicola,
           I agree with your comment, but the cell estimation
algorithm changed: we now estimate the number of required
cells from the number of requested cells (to add or delete)
and the number of effectively used cells. What is still not clear
to me is if the simulation results from the OTF paper is still valid
given this change. To enable the cell estimation algorithm without
packet loss, we need to guarantee always a small amount of
overprovisioning.
          Let me bring the lost text (from OTF) back to SF0.
          Regards,

                                         Diego

2016-11-02 11:36 GMT-03:00 Nicola Accettura <nick.accettura@gmail.com>:

> Hi Tengei,
>
> the problem you are rising is that you would like to see a number of cells
> to add/delete when comparing required and deleted cells.
>
> The ancestor of SF0, namely OTF, used to specify the following sentence:
>
> The number of soft cells to be scheduled/deleted for bundle resizing
>    is out of the scope of this document and implementation-dependant.
>
> In fact, we wanted to let that choice being implementation specific.
>
> What you are proposing (the exact number of cells to add or delete) was
> already implemented in the 6tisch simulator, and it is in fact something
> that has already been used and tested in the following papers:
>
> Palattella et al., On-the-Fly Bandwidth Reservation for 6TiSCH Wireless
> Industrial Networks, IEEE Sensors Journal, 2015
>
> Muraoka et al., Simple Distributed Scheduling with Collision Detection in
> TSCH Networks, IEEE Sensors Journal, 2016
>
> But, as already said, this is just a way you can allocate cells. I guess
> we don't want to restrict that setting to a particular algorithm choice.
>
> Hope this helps.
>
> Nicola
>
> 2016-11-02 14:59 GMT+01:00 Tengfei Chang <tengfei.chang@gmail.com>:
>
>> Hi All,
>>
>> I am reading the SF0-02 version which is just released few days ago.
>>
>> In the SF0 Allocation Policy section, the policy said
>>
>>    1.  If REQUIREDCELLS<(SCHEDULEDCELLS-SF0THRESH), delete one or more
>>        cells.
>>    2.  If (SCHEDULEDCELLS-SF0THRESH)<=REQUIREDCELLS<=SCHEDULEDCELLS, do
>>        nothing.
>>    3.  If SCHEDULEDCELLS<=REQUIREDCELLS, add one or more cells.
>>
>>
>>
>> Personally thinking, add/delete one cells may call the sixtop many times
>> which is not efficiency, add/delete more cells is not clear to the
>> implementer.
>> I guess there is a decision to say when to add one cell and when to add
>> more cells. But I didn't find it in SF0 draft.
>> Is there any reason why we doesn't say specific number of cells?
>>
>> If no, I think we can add/remove the number of cells to make sure the
>> scheduled cells equals to the required cells plus half of SF0THRESH, which
>> will help stabilize a little bit of the SF0, in case the sixtop is calling
>> too often.
>>
>> Which means: if SCHEDULEDCELLS<=REQUIREDCELLS:
>>
>> 1. when there is no cell in the schedule add one cell
>> 2. when there is at least one cell in schedule, add
>> REQUIREDCELLS-SCHEDULEDCELLS+(SF0THRESH+1)/2 number of cells
>>
>> if REQUIREDCELLS<(SCHEDULEDCELLS-SF0THRESH))
>>
>> 1. When required cells equals 0, remove all cells but keep one in schedule
>> 2. when required cells is greater than 0, remove  SCHEDULEDCELLS-
>> REQUIREDCELLS-(SF0THRESH+1)/2
>>
>> Does this make sense?
>>
>> Tengfei
>>
>> --
>> Chang Tengfei,
>> Pre-Postdoctoral Research Engineer, Inria
>>
>> _______________________________________________
>> 6tisch mailing list
>> 6tisch@ietf.org
>> https://www.ietf.org/mailman/listinfo/6tisch
>>
>>
>
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>


-- 
DIEGO DUJOVNE
Profesor Asociado
Escuela de Informática y Telecomunicaciones
Facultad de Ingeniería - Universidad Diego Portales - Chile
www.ingenieria.udp.cl
(56 2) 676 8125