Okumura Hata Model formula | COST-231 extension of Hata Model

This page describes Okumura Hata Model basics, Hata model formula and COST-231 extension of Okumura Hata Model.

The hata model is empirical formulation of graphical path loss (PL) data. It is valid in the range from 150 MHz to 1500 MHz. It is provided by Okumura and hence the name. Hata has given standard formula for propagation loss for urban area. He has also provided correction equations for other situations.

There are two forms of Okumura Hata model as mentioned below.
➨In first form, path loss (dB) is expressed as follows:
PL = PLfree space + Aexc + Hcb + Hcm
Where,
PLfree space = Free space Path Loss
Aexc = Excess Path Loss for BS height of 200 meters and MS height of 3 meters.
Hcb, Hcm = Both are correction factors

➨Standard formula for path loss is expressed as follows.
PL = A + B*Log(d) + C
Where, A, B abd C are factors which depend on both frequency and height of antenna.
A = 69.55 + 26.16 Log (Fc) -13.82*Log(hb)-a(hm)
B = 44.9 - 6.55Log (hb)
Where,
Fc is frequency in MHz
d is distance in Km
hb is BS height
hm is MS height
Function a(hm) and factor C depend on environment as mentioned below.

The a(hm) in suburban/rural areas is same as for urban areas.

COST-231 extension of Hata Model

The empirical path loss formula is expressed as follows.

EURO COST group has formed COST-231 working committee to develop extended version of Hata model. The formula above extends Hata model to about 2 GHz.