Hi Bibudh n all
Im using at the moment TOSSIM for delay calculations and not using real motes.
Therefore for delay calculation, truly i didnt think of time synchronization
coz i was considering the global times ie tos_state.tos_time so i was assuming
that subtracting the time of sendDone() from time of receive will give me some
approximated form of delay time at the global simulator time.
Second option can be to use -b=0 option of simulator to boot all nodes at same
time to have some sort of sync.
Any comments on this
Regards
Faisal
----------------------------------------------------------------------
Message: 1
Date: Mon, 2 Apr 2007 10:52:34 -0500
From: "Bibudh Lahiri" <[EMAIL PROTECTED]>
Subject: Re: [Tinyos-help] sendDone() called before receive
To: [email protected]
Message-ID:
<[EMAIL PROTECTED]>
Content-Type: text/plain; charset="iso-8859-1"
Hi Faisal,
If u want to measure the transmission delay, how can u do it by noting
the time of transmission and reception from the sender and the receiver
respectively, until their clocks are synchronised to each other? Have u
already taken care of this synchronisation?
One scheme I can suggest for measuring the end-to-end delay (round-trip)
is, once the message reaches the destination from the src by the multi-hop
path, send some kind of reply/ACK message all the way back to the sender,
following the same route. Notice the time when this reply/ACK reaches the
original src, and take the time difference with the time the message was
sent out from this sender, divide it by 2.
My approach may sound too naive, let's see if someone else comes up with
some better idea.
Bibudh
Bibudh Lahiri
Graduate Research Assistant
Department of Electrical and Computer Engineering
Iowa State University
http://www.ece.iastate.edu/~bibudh/
On 4/2/07, Faisal Karim <[EMAIL PROTECTED]> wrote:
>
> Thanks for replies.
> I got the idea, but still at one hop the behavior should be like once the
> source send one packet sendDone shd be called after that receiver's
> recieve() method.
>
> Actually im trying to calculate the delay between transmission and
> reception. I have put DBG statement in src's sendDone() and DBG statement in
> receiver's recieve() method. When i try simulation of two nodes always DBG
> of receiver invokes first than src's DBG. if someone knows some method to
> calculate delay than it will be more than good.
>
> Regards
> Shaikh, Faisal Karim
>
>
>
>
> ------------------------------
>
> Message: 5
> Date: Sun, 1 Apr 2007 20:58:56 -0700
> From: Philip Levis <[EMAIL PROTECTED]>
> Subject: Re: [Tinyos-help] sendDone() called before receive
> To: Thang Le <[EMAIL PROTECTED]>
> Cc: [email protected]
> Message-ID: <[EMAIL PROTECTED]>
> Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
>
> On Apr 1, 2007, at 7:02 PM, Thang Le wrote:
>
> > From my understanding, in TinyOS 1.1.15, SendDone is invoked when
> > the package is successfully queued at the sender. Even without any
> > receiver, SendDone is still called.
> >
>
> sendDone is signaled when the packet is transmitted. The error code
> denotes whether or not the transmission succeeded. Reasons for
> failure can include the radio being turned off mid-transmission,
> hardware failure, etc.
>
> You will never receive a sendDone before the packet is transmitted.
> That would release the packet buffer to the application, which is
> problematic.
>
> Note that since sendDone denotes a data-link (single-hop)
> transmission, it is signaled when the packet goes one hop, not the
> multihop frame within arrives at its destination.
>
> Phil
>
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Message: 2
Date: Mon, 2 Apr 2007 12:21:14 -0400 (EDT)
From: "Benjamin Madore" <[EMAIL PROTECTED]>
Subject: Re: [Tinyos-help] sendDone() called before receive
To: "Bibudh Lahiri" <[EMAIL PROTECTED]>
Cc: [email protected]
Message-ID:
<[EMAIL PROTECTED]>
Content-Type: text/plain;charset=iso-8859-1
On Mon, April 2, 2007 11:52 am, Bibudh Lahiri said:
> One scheme I can suggest for measuring the end-to-end delay (round-trip)
> is, once the message reaches the destination from the src by the multi-hop
> path, send some kind of reply/ACK message all the way back to the sender,
> following the same route. Notice the time when this reply/ACK reaches the
> original src, and take the time difference with the time the message was
> sent out from this sender, divide it by 2.
>
> My approach may sound too naive, let's see if someone else comes up with
> some better idea.
>
> Bibudh
>
I would agree calculating on the ACK (by setting auto-ACK) and dividing by 2
is your best bet short of lots of hardware monitoring equipment.
BTW-Round-trip would be the full time from send to ACK. End-to-end would be
approximately round-trip/2. There may be some computing time in between on
round-trip, but it is likely trivial, and in the "real world" the amount of
time it takes the MAC to signal receive or to transmit is part of the delay.
Pure signal timing assumes infinitely fast code in all parts of the MAC,
which will never happen.
Draw your lines appropriately.
--
The difference between the right word and the almost right word is really a
large matter- it's the difference between a lightning bug and the lightning.
-Twain
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