Re: Varying a transmission range of mobile node

[Satish Kumar <kkumar@ISI.EDU>]

ns currently uses the free space propagation model when the nodes are within a 
certain reference distance ("cross-over" distance) from each other and the 
two-ray ground reflection model for greater distances. Look at 
ns-2/tworayground.cc for the cross-over distance computation and the equations 
for the propagation models. You can back-calculate the appropriate Pt_ from 
these equations by setting Pr_ equal to the receive threshold and d to the 
desired transmission range. You can find values for some of the parameters 
(such as receive threshold, lambda etc.) required in these equations in 
wireless-phy.cc (in the WirelessPhy constructor).

Satish


> Dear Collegues,
> 
> I am implementing some routing protocols in ad hoc networks
> using the ns-2.1b6 and the cmu-ported wireless network environments. 
> 
> Here, for example in DSR or DSDV implementation, a default transmission
> range of each mobile node is 250m - all scenario files generated by
> "setdest.cc" calculate nodes' connectivity info using this default
> transmission range value. 
> 
> Now, I want to vary the transmission range, such as into 200m or 300m.
> (As far as I know, in order to vary it, we need to change the 'Pt_'
> variable in the source code of "wireless-phy.cc" - currently defined 
> as 'pow(10,2.45) * 1e-3' with a comment of 24.5 dbm, ~ 281.8mw. 
> But, I don't know how this Pt_ value is converted into 'meter' unit.
> For example, what does the equation of Pt_ look like if I want 200m, 
> 300m, or 400m transmission range?) 
> 
> Please answer me ASAP about which files I should modify to do that.
> Thank you in advance,
> 
> - Youngbae
> 
> /* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
>      Young-Bae Ko    {youngbae@cs.tamu.edu}
> 
>      http://www.cs.tamu.edu/people/youngbae
>      Dept. of Computer Science   [Tel] 409-845-5007 
>      Texas A&M University        [Fax] 409-847-8578
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