Varying a transmission range of mobile node

[Youngbae - Ko <youngbae@cs.tamu.edu>]

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
/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */