Propagation Loss Models ns-3

Question

I am using ns-3 and I am doing a network with 3 stations and 1 AP. It works fine but then I have to analyse it with the cost 231 model (Cost Hata) and with the Friis model. I observed that if you put one station away , using the Friis model allows much larger distances. Is there a particular reason for this?

Answer 1

The explanation for this behavior due to the different of environmental assumptions of the two models: COST-Hata assumes urban scenario while Friis assumes a free space scenario.

In urban scenario the signal attenuates very quickly due to the reflection, refraction and signal blocking due to imaginary buildings and walls. While In free space signal can reach longer distance based on the signal strength.

This means that on using the Friis model with small transmission power several nodes are reached. This results in short paths, but also in high contention. With the urban models more transmission power is required to reach nodes behind imaginary walls.

To understand different behavior for NS3 propagation models check the following paper Comparing the ns-3 Propagation Models