Wireless Network Design: Optimization Models and Solution ...

52 K. V. S. Hari
terms have been proposed [11]. The path loss model (in dB) with the correction
terms would be
PLmodi f ied = PLa + ∆PL f + ∆PLh
where ∆PL f (in dB) is the frequency correction term given by
(3.9)
∆PL f = 6log( f /2000) (3.10)
where f is the frequency in MHz, and ∆PLh (in dB) is the receive antenna height
correction term given by ∆PLh = −10.8log(h/2) for Categories A and B and
∆PLh = −20log(h/2) for Category C h is the receive antenna height between 2
m and 10 m.
Path Loss Models for indoor stationary/low-mobility applications: As an example,
if the transmitter and receiver are both indoors, the indoor path loss model (dB)
for the ITU M.1225 model is based on the COST 231 model[1, 2] and is given
below.
( n+2
PL(dB) = 37 + 30log10 d + 18.3n n+1 −0.46)
(3.11)
where d(m) is the transmitter-receiver separation and n is number of floors in the
path. A log-normal shadow fading standard deviation of 12 dB can be expected in
such an environment.
Similarly, for the case where the receiver is indoor and the transmitter is indoor,
the path loss model is given by
PL(dB) = 40log 10 d + 30 log 10 f + 49 (3.12)
where d(km) is the transmitter-receiver separation and f is in the 2GHz band. The
model can be modified to include the antenna system parameters and expressed as
PL(dB) = 40(1 − 0.004∆hb)log 10 d − 18log 10 ∆hb + 21log 10 f + 80 (3.13)
where d(km) is the transmitter-receiver separation, ∆hb is the base station antenna
height (m) measured from the average rooftop level (0 ≤ ∆hb ≤ 50), f is in the
2GHz band.
3.4.2 Rayleigh and Ricean Flat Fading Channels
The analysis of experimental data led to the modeling of a wireless channel as a
random process. The fact that the signal is a superposition of several faded signals
and the use of the central limit theorem leads to the modeling of the channel as a
Gaussian random process.
Rayleigh channel: The amplitude of a channel which is modeled as a zero mean
complex Gaussian random process has a Rayleigh distribution. Such channels are
called Rayleigh channels and occur when there is a non-line-of-sight (NLOS) com-