In this model, the shadowing fading factor is not considered. Therefore, for a unique distance, the Pr is a determinstic value. Usually, tworayground has two formulas:
Pr = PtGtGrht2hr2
/ (Ld4)
Based on the default settings in ns-2, we can derive a relationship between Pr and distance
Default parameter in ns-2:
| Distance | Pr |
| 15m | 2.81838e-5 |
| 20m | 8.91754e-6 |
| 22m | 6.0908e-6 |
| 30m | 1.7615e-6 |
| 60m | 1.1009e-7 |
| 120m | 6.8808e-9 |
| 200m | 8.9175e-10 |
| 210m | 7.3365e-10 |
| 220m | 6.908e-10 |
| 230m | 5.0986e-10 |
| 240m | 4.3005e-10 |
| 250m | 3.6526e-10 |
| 300m | 1.7615e-10 |
| 350m | 9.5081e-11 |
| 400m | 5.5735e-11 |
| 450m | 3.4795e-11 |
| 500m | 2.2829e-11 |
| 550m | 1.5592e-11 |
| 600m | 1.1009e-11 |
| 650m | 7.993e-12 |
| 700m | 5.9425e-12 |
| 750m | 4.5094e-12 |
In reality, path loss index is only 2 in near distance. Therefore, for near-distance (<25m) , the above formula does not apply. When distance is less than ~25 meter, the Friss model will be used. Check tworayground.cc for detail