Okumura Hata Model and COST-231 Extension

This page explains the basics of the Okumura Hata Model, including the Hata model formula and the COST-231 extension. The Hata model is an empirical formulation of graphical path loss (PL) data, valid in the range of 150 MHz to 1500 MHz. It’s named after Okumura, who provided the original data.

Hata provided a standard formula for propagation loss in urban areas, along with correction equations for other environments. There are two forms of the Okumura Hata model:

Forms of the Okumura Hata Model

First Form: Path Loss Expression

The path loss (in dB) is expressed as follows:

$PL = PL_{free\ space} + A_{exc} + H_{cb} + H_{cm}$

Where:

• $PL_{free\ space}$ = Free space Path Loss
• $A_{exc}$ = Excess Path Loss for BS height of 200 meters and MS height of 3 meters
• $H_{cb}, H_{cm}$ = Correction factors

Second Form: Standard Path Loss Formula

The standard formula for path loss is:

$PL = A + B * Log(d) + C$

Where A, B, and C are factors that depend on both frequency and antenna height.

• $A = 69.55 + 26.16 * Log(F_c) - 13.82 * Log(h_b) - a(h_m)$
• $B = 44.9 - 6.55 * Log(h_b)$

Where:

• $F_c$ is the frequency in MHz
• $d$ is the distance in Km
• $h_b$ is the BS (Base Station) height
• $h_m$ is the MS (Mobile Station) height

The function $a(h_m)$ and factor $C$ depend on the environment, as shown below:

The $a(h_m)$ value for suburban/rural areas is the same as for urban areas.

COST-231 Extension of the Hata Model

The empirical path loss formula for the COST-231 extension is as follows:

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