[Veins] number of collisions

[Nader.Ch]

Dear all,

I have just started working on Veins for vanet simulation. I want to determine the number of collisions (either due to simultaneous reception of multiple packets or to weak signal from a sender in sensing range).

Should I just use the counter "statsSNIRLostPackets" (which is incremented Mac1609_4::handleLowerControl when receiving a message with "getking == Decider80211p::BITERROR") or do I have to retrieve this information directly from physical layer?


thanks in advance.

Nader

[David Eckhoff]

Hallo Nader,

> I want to determine the number of collisions (either due to simultaneous reception
> of multiple packets or to weak signal from a sender in sensing range).

> Should I just use the counter *"statsSNIRLostPackets*" (which is
> incremented *Mac1609_4::handleLowerControl* when receiving a message

> with "getking == Decider80211p::BITERROR")

This depends on whether you really want to record the number of
collisions or rather the number of all packets that could not be decoded.
In Veins2.0rc2 all messages which could not be decoded result in a
controlMessage for the Mac Layer (Decider80211p::BITERROR).
Hence, you can use the statsSNIRLostPacket counter.

If you want to distinguish between packets that could not be decoded due
to interference from other packets and packets with too low signal
strength you would have to add this feature to the decider.

In the next version of veins we will include this feature, along with a
simple frame capture model. I hope we can release the new version within
the next week or the week after.

Greetings,
David

--
Dipl.-Inf. Univ. David Eckhoff
Computer Networks and Communication Systems
University of Erlangen, Germany
Phone: +49 9131 85-27627 / Fax: +49 9131 85-27409
mailto:eck...@cs.fau.de
http://www7.cs.fau.de/~eckhoff/

[Ali Balador]

Hi David Eckhoff,

Could you please tell me how I can distinguish between packets that could not be decoded due  to interference from other packets and packets with too low signal strength.

Thanks.

[Alfonso Ariza Quintana]

In the reality

First case, received signal high, bad s/n -> CRC error -> collision

Second case, received signal low, CRC error ->bit error

 

In the code, in inetmanet the radio module return the error cause

        PhyIndication frameState = radioModel->isReceivedCorrectly(airframe, list);

        if (frameState != FRAMEOK)

        {

            airframe->getEncapsulatedPacket()->setKind(frameState);

            airframe->setName(frameState == COLLISION ? "COLLISION" : "BITERROR");

 

            numGivenUp++;

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