Point-to-point Lee model

The Lee model for point to point mode is formally expressed as:

${\displaystyle L=L_{0}+\gamma g\log d-10\left(\log {F_{A}}-2\log \left({\frac {H_{ET}}{30}}\right)\right)}$

where,

L = The median path loss. Unit: decibel (dB)

L₀ = The reference path loss along 1 km. Unit: decibel (dB)

${\displaystyle \gamma \;}$ = The slope of the path loss curve. Unit: decibels per decade

d = The distance on which the path loss is to be calculated. Unit: kilometer (km)

F_A = Adjustment factor.

H_ET = Effective height of terrain. Unit: meter(m)

The reference path loss is usually computed along a 1 km or 1 mi link. Any other suitable length of path can be chosen based on the applications.

${\displaystyle L_{0}=G_{B}+G_{M}+20\left(\log \lambda -\log d\right)-22}$

where,

G_B = Base station antenna gain. Unit: Decibel with respect to isotropic antenna (dBi)

${\displaystyle \lambda }$ = Wavelength. Unit: meter (m).

G_M = Mobile station antenna gain. Unit: decibel with respect to isotropic antenna (dBi).

The adjustment factor is calculated as:

${\displaystyle F_{A}=F_{BH}F_{BG}F_{MH}F_{MG}F_{F}}$

where,

F_BH = Base station antenna height correction factor.

F_BG = Base station antenna gain correction factor.

F_MH = Mobile station antenna height correction factor.

F_MG = Mobile station antenna gain correction factor.

F_F = Frequency correction factor

${\displaystyle F_{1}=\left({\frac {h_{B}}{30.48}}\right)^{2}}$

where,

h_B = Base station antenna height. Unit: meter.

${\displaystyle F_{2}={\frac {G_{B}}{4}}}$

where,

G_B = Base station antenna gain. Unit: decibel with respect to half-wave dipole (dBd)

${\displaystyle F_{3}={\begin{cases}{\frac {h_{M}}{3}}\qquad {\text{ if, }}h_{M}\leq 3\\({\frac {h_{M}}{3}})^{2}\quad {\text{ if, }}h_{M}>3\end{cases}}}$

where,

h_M = Mobile station antenna height. Unit: meter.

${\displaystyle F_{4}=G_{M}}$

where,

G_M = Mobile station antenna gain. Unit:Decibel with respect to half wave dipole antenna (dBd).

${\displaystyle F_{5}=\left({\frac {f}{900}}\right)^{-n}{\text{ for }}2<n<3}$

where,

f = Frequency. Unit: megahertz (MHz)

This is computed in the following way:

1. Extrapolate terrain slope at the mobile station to the base station.
2. Compute the vertical antenna height over the extrapolation line.