[ns] Calculate Signal strength in ns2

[Liceven]

Hello, Daniel,
   I have a same question. You said after you changed "set opt(prop)
Propagation/TwoRayGround" to  
"set opt(prop) Propagation/FreeSpace" the console could output the
information correctly. So, I am wondering how can you do that, I mean could
you please be kindly to give me an example to show how it works. THanks very
much
Regards.
Liceven

Daniel Rother wrote:
> 
> 
> Hi,
> I've got the same problem. In tcl I haven't found a solution. I  
> thougth there is something easy like "set strength [$node set  
> signalstrength]" but it seems there isn't such a think... :(
> Because of that I go to the C++-Source-Code. After a little bit of  
> searching I found the file "wireless-phy.cc" and there the function  
> "sendUp". I think there the variable "Pr" is the signal strength  
> (because later in the function "Pr" is compared with "CSTresh_" and  
> "RXTresh_" wich a used to simulated if a paket is recieved correct or  
> not).
> But now I had the problem that "Pr" alway had got the same value and I  
> don't know why. I went back to my tcl file and play a little bit with  
> my settings. As I changed "set opt(prop) Propagation/TwoRayGround" to  
> "set opt(prop) Propagation/FreeSpace" and start a simulation, I've got  
> an output on my console like "time: 0.008566: d: 31.622777, Pr:  
> 2.949347e-09" (and there the Pr is chaniging!). First I was wondered  
> about that, but then I looked into the file "propagation.cc" and there  
> I found in the function Pr() "printf("%lf: d: %lf, Pr: %e\n",  
> Scheduler::instance().clock(), d, Pr);". So I copy that and put it  
> into the file "tworayground.cc" at the same position (the function Pr)  
> and now it seems to work.
> But I always have a question: Why is Pr in "tworayground" changing and  
> in "wireless-phy" not? And is it the correct position to read out the  
> signal strength?
> I've alway looked into the file "mac-802_11.cc" and the function  
> "send" but there "Pr" also seems not to work correct (there it is  
> alwas "1.600278e-02" or "-1"...) What do I have to change?
> And a last thing: I want to have the signal strength in dBm. Because  
> of that I made "10*log10(Pr)" but I'm not sure if I have to use  
> "10*log10(Pr/0.001)" instead (because 1mW is the referece value for  
> dBm and I don't know if it is include in Pr or not...)
> I hope anybody can help me with my problem(s). Thanks!
> Greets Daniel Rother
> 
> 
> Zitat von angelina socratous <trypes247 at hotmail.com>:
> 
>>
>>
>> I have a topology with some access points and some wireless nodes   
>> attached to them. If a new node wants to join the network how can i   
>> get the signal strength which the new node receives from each access  
>>  point?
>> Should i use c++? If someone has a tutorial for this task it would   
>> be very helpful.
>>
>> Thanks, Angelina
>> _________________________________________________________________
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> 
> 
> 
> 
> 
> 

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