I would have great doubts about getting any useful information
on actual transmission times from TOSSIM, and any (well, most)
measurement paradigms that you come up with will probably not
be easy to transport to the real world.
The previous suggestion of timing transmit-to-ack is one approach,
but I'd still bet that the simulator doesn't behave the way a
real system does.
I did a set of, now perhaps obsolete, measurements with real mica2's
and a bit with 'Z's a year or so ago. I used a command/reply cycle
to time response from the PC side and was interested in total
throughput and lost packets. You can see the results and code at:
http://www.etantdonnes.com/Motes/
MS
Bibudh Lahiri wrote:
Hi Faisal,
As an idea, it sounds OK, but I'd like to mention a thing or two:
1) I'm not sure how close this would be to the transmission delay that
u'd obtain on real motes
2) If the problem of receive() being called in the receiver before
sendDone() being called in the sender persists (as u reported), then
u'll have a problem.
On 4/2/07, *Faisal Karim* <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
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] <mailto:[EMAIL PROTECTED]>>
Subject: Re: [Tinyos-help] sendDone() called before receive
To: [email protected]
<mailto:[email protected]>
Message-ID:
<[EMAIL PROTECTED]
<mailto:[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]
<mailto:[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] <mailto:[EMAIL PROTECTED]>>
> Subject: Re: [Tinyos-help] sendDone() called before receive
> To: Thang Le < [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>>
> Cc: [email protected]
<mailto:[email protected]>
> Message-ID: < [EMAIL PROTECTED]
<mailto:[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]
<mailto:[EMAIL PROTECTED]>>
Subject: Re: [Tinyos-help] sendDone() called before receive
To: "Bibudh Lahiri" <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>>
Cc: [email protected]
<mailto:[email protected]>
Message-ID:
< [EMAIL PROTECTED]
<mailto:[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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