Re: [Roll] Fwd: New Version Notification for draft-tripathi-roll-rpl-simulation-01

[Joydeep Tripathi <[e-mail]>]

Hi,

On Thu, Dec 24, 2009 at 2:25 AM, Philip Levis <[e-mail]> wrote:
>
> On Dec 23, 2009, at 10:24 PM, Joydeep Tripathi wrote:
>
>> On Wed, Dec 23, 2009 at 2:52 AM, Omprakash Gnawali
>> <[e-mail]>
>>  wrote:
>>>
>>> I managed to find the pdf with the graphs. Here are some comments.
>>>
>>> It will help greatly if more information about the link model were
>>> included. -01 mentions:
>>>
>>> "* Link failure model: Time varying real network traces containing
>>> packet delivery probability for each
>>> link and over all channels for both indoor network deployment and
>>> outdoor network deployment were used.
>>> Thus, di erent types of link characteristics are used in the study.
>>> * Topology: The topologies are gathered from real-life deployment
>>> (traces mentioned above) as opposed
>>> to random topology simulations. are repeated here:"
>>>
>> Actually,we collected real-life traces with hundreds of links varying
>> with time for the network,  and simulated the same variation in PDR
>> for each link as in the real deployment.
>
> I don't understand -- how do you do this? There has to be some interval over
> which you average, unless you are replaying success/failure traces. Link can
> very much faster than every ten seconds.

Actually you are right, the PDR value of a link is averaged over 100
packets over an interval. When the trace was gathered, during each 15
minutes interval, 100 packets are transmitted over a link in the
network. Out of 100 packets, number of successfully received packets
was count for each link between two communicating nodes that are
physically one hop away. The number of successfully received packets
out of 100 packets originally transmitted was recorded as the PDR of
the link after each 15 minutes interval. In our simulation, we
consider the PDR between those two nodes to be constant during a 10
minutes interval. When an interval gets over, we consider the next PDR
value between same two nodes in the database of traces, that was
collected during the next interval and use that value for next
interval.

I hope this clarifies how the link quality traces are gathered and
used. Please let me know if you have further questions.

Thanks,
Joydeep
>
> Phil
>
>