Tworaygrond Model

[ Back to Network Simulator 2 for Wireless ]

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

Cross-distnace Effect

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 for detail