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

[Omprakash Gnawali <[e-mail]>]

On Tue, Dec 29, 2009 at 6:58 PM, Joydeep Tripathi
<[e-mail]> wrote:
> 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.

Each node sends a packet every 9 seconds to estimate the link quality
and the estimate is updated every 100 packets?

Do you consider datarate in your simulation?

I did not understand why data collection uses a window of 15 mins and
data use uses a window of 10 mins.

- om_p