Ns2 uses the two ray model

https://en.wikipedia.org/wiki/Two-ray_ground-reflection_model

Pr = Pt (Gr Gt hr ht)/d⁴

You only need to adjust the Pr like rxThreh_ and Pt like pt_

Take a look at these references:

https://arxiv.org/ftp/arxiv/papers/1202/1202.3576.pdf

https://ns2blogger.blogspot.com/2014/04/different-transmission-range-for-nodes.html

https://slogix.in/how-to-set-different-transmission-range-for-each-node-in-ns2#Source-code

regards

Alfonso Ariza Quintana , the receiving threshold (pr) depends on the transmit power (pt_) .

Also in ns2, pr can be computed from the /indep-utils/propagation/thresold.cc for different transmission ranges.

but it takes the default transmit power (pt_) value of 0.2818, (250 meter transmission range).

then how to compute the transmit power (pt_) for 1.5 KM

Please refer this .

https://core.ac.uk/download/pdf/36696200.pdf

Salim M. Zaki

the receiving threshold can be computed from thresold.cc for different transmission ranges.

However the mentioned links, does not provide any details for the calculation of the transmission power (Pt).

In this case, see this discussion, it may help:

https://groups.google.com/forum/#!topic/ns-3-users/VTJzNjNVAyA