[ns] transmit power - does it really control transmission range?

[Md. Atiur Rahman Siddique]

Hi Sita,

In my opinion you dont define threshold like that. You need to ensure:
1. The receiving node can sense the signal.
2. If multiple signal arrive at the same time the signal to noise ratio is greater its threshold.

You need to set three vars or use default vals with care:

RXThresh_: Received signal strength has to be greater than this for the packet to be successfully
received.

CSThresh_: Received signal strength has to be greater than this for the packet transmission to be
sensed. So,  CSThresh_ should be smaller or equal to RXThresh_ for a real case.

CPThresh_: With multiple signal being received the ratio of stregths of strongest signal to the
second strongest one has to be greater that this. If it is not both are truncated. I think (check
for yourself) in NS they check only the strongest two signals which is wrong in my opinion. It
should be the original signal and the sum of all other signals. I think they do it in glomosim.

-Atiur

--- "Sita S. Krishnakumar" <sita at ece.gatech.edu> wrote:

> I am using two ray ground propogation. Let me try to understand this: If I
> have a source node with transmission range of 250m and a destination node
> 100m away with receiving threshold of 20m, will packets from source be
> received by destination node?
> 
> -Sita
> 
> 
> >
> > The transmission range depends on the transmitted power, propagation model
> > and recv thershold. So,
> > yes, I think all the nodes are not connnect with these values.
> >
> > -Atiur
> > --- "Sita S. Krishnakumar" <sita at ece.gatech.edu> wrote:
> >
> >>
> >>
> >> > Hi,
> >> > I am working with a sparsely connected network in a 200m by 200m
> >> field.
> >> > The default transmit power of 0.281838 corresponds to a 250m
> >> transmission
> >> > range. I have a node in the center with this Pt_ and when it sends out
> >> > packets, all the nodes in the network do not seem to receive it. Why?
> >> >
> >> > On a separate note, setting CsThresh_ and RxThresh_ does limit the the
> >> > sensing range and receiving range of the nodes (which I have at 20m).
> >> Does
> >> > this in any way cause the impediment?
> >> >
> >> > Thanks,
> >> > Sita
> >> >
> >> >
> >>
> >>
> >>
> >
> >
> >
> >       ____________________________________________________________________________________
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> >
> >
> 
> 
> 


Best Regards.
-Atiur


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