Re: 回复： Re: [Tinyos-help] help:packets cannot be received in lossy model in TOSSIM

[Nikolas]

Mmm are you sure you are actually sending anything?
You might have forgotten to wire some components.
Check if send in $(TOSDIR)/platform/pc/packet/TossimPacketM.nc gets
called (that's the packet-level radio model).
By looking at that code you should be able to figure out what's going on.


On 03/06/07, qiting chen <cqt_chaos at yahoo.com.cn> wrote:
> Hi,Nikolas
> much appreciated your help!
> a)I've set all the bit-error-rate to zero,so all the bit should be recevied
> correctly,I think.
> b)I tried the packet-level radio model.I just modified the makefile without
> rewiring the components.Still,none of the packets sended can be received at
> the route level.
>
> ps:in the simple model,packets can be received successfully.
>
> can you give me some futher instructions?
> Best regards!
>
> Nikolas <n.pontikos at gmail.com> 写道：
>
> On 03/06/07, qiting chen wrote:
> > Hi,all
> > I tend to use the lossy model in TOSSIM(tinyos1.15) and met a problem.
> > The problem is that in the lossy model, no packet reception will ever
> > occure though I've set the bit error rate to zero.While in simple
> > model,packets can be received successfully.
> > To use the lossy model,I've creadted lossy.nss in the app directory.At
> > the beginning of the dbg message,it says:
> > SIM: EEPROM system initialized.
> > Initializing lossy model from lossy.nss.
> > 0: RFM connectivity graph constructed.
> > However,packets sent can no longer be received as long as the lossy model
> > is used.
> > Can anyone help me sovle the problem
> >
> > thanks in advance.
>
> First, may I suggest you explore this further by using dbg statements
> in the simulator code.
> Also check the TOSSIM document: just google nido.pdf.
>
> I can see 2 possibilities:
> a) your packets arrive corrupted at the receiver and are subsequently
> dropped
> b) your packets are not sent at all
>
> If a):
> Your bit-error-rate in lossy.nss might be too high so all received
> packets are lost. The TOSSIM document explains the formula used to
> calculate loss-rate from the bit-error-rate. The loss-rate is
> dependent on the size of the packets and the bit-error-rate.
>
> If b):
> I assume you are using the bit-level radio model of the simulator, as
> opposed to the packet-level simulator. If you are, you need to be
> aware that the bit-level radio model can be very slow. So you might
> simply not be waiting long enough. Depending on your needs you might
> consider using the packet-level radio model. It's faster but less
> accurate (no CSMA, no collisions, no hardware acks). To use it, just
> add this in your Makefile:
> PFLAGS += -I$(TOSDIR)/platform/pc/packet
>
>
>
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