Final report on link level and system level channel models - Winner

WINNER D5.4 v. 1.4
5.5.6 Scenario D1
5.5.6.1 Path-loss
5.5.6.1.1 LOS path-loss
The basic theoretical equation for LOS path-loss is
where d is the distance between BS and MS and A and B are constants.
PL = A + B*log 10 (d) (5.45)
Normally, A and B are near the free-space values. For example, in our measurements at 5.25 GHz the
values were: A = 41.8 and B = 22.
The model in (5.34) can be extended until so called break-point distance, which depends on the wavelength
? and base station and mobile station antenna heights, h BS and h MS respectively [28].
d BP = 4 · h BS · h MS / ? (5.46)
where h BS is the height of the base station, h MS is the height of the mobile station, and ? is the wave length
at f c .
After this break-point, the loss is proportional to another, greater path-loss exponent. By flat earth theory,
this exponent should be 4, but in practice it can be also greater. The model is based on the assumption
about two rays arriving at the receiver antenna, one direct ray, the other one reflected from the flat earth.
This model is also called two-ray model.
The model can be written in the form [28]:
PL = A + B log 10 (d), d d BP (5.48)
where C = 10 n, and n is the path-loss exponent for the distances greater than the break-point distance.
Other constants are as given above.
About LOS path-loss, there is a statement in [13] about trials in an rural environment that show that the
two-ray model woks well there. For the urban microcellular environment it has been modified slightly to
make it agree with the measurement results. Measurements for the two-ray modeling were <strong>report</strong>ed at 1.9
GHz and cover the range of 0 to 1800 m with antenna heights of 6 m (BS) and 1.7 m (MS). With these
values the distance of 1800 m is far beyond the break-point distance.
Also, [AlPM02] shows results for LOS conditions, where the path-loss exponent is near 2 with standard
deviation of 6.9 dB. The behavior of the path loss is thus like in free-space. The environment is called
residential. It can be classified also suburban. Measurements were conducted using 100 MHz bandwidth.
For NLOS conditions, the path-loss exponent was 3.5 and the standard deviation was 9.5 dB.
In the reference [Zha02], based on measurements performed at 5.3 GHz with RF BW 30 MHz, and omnidirectional
antennas, the path-loss models, excess delay and RMS delay-spread statistical values were
obtained. In the rural environments, the transmitter was placed at a hill with a mast, the total height was
55 m from ground level, the height of the mobile station was 2.5 m on top of a car. The path-loss equation
is expressed as follows:
5.5.6.1.2 NLOS path-loss
PL ( dB) = 21.8 + 33log
10
( d ) , σ = 3. 7 dB (5.49)
The model has been based partly on measurements and partly on literature. There are numerous path-loss
models for lower frequencies than 5 GHz, and especially for urban and suburban environments. For the
rural environment at 5 GHz there are not many results available. One alternative is to use results of lower
frequencies, e.g. 2 GHz and translate them to 5 GHz. This can be justified with results presented in the
paragraph 5.5.6.1.4, which show that the path-loss properties at 2 and 6 GHz are closely related. Mean
difference was found to be 8.1 dB, when the difference due to the free-space losses should be 9.7 dB.
Although the results were measured in an urban environment, they suggest that the rural 2 GHz path-loss
model can be converted to 5 GHz by increasing the path loss with the difference in the free-space losses.
One potential channel model for the D1 scenario is the COST-231-Hata model [26] that is converted for 5
GHz. COST-231-Hata model for sub-urban environment is
d
PL = ( 44.9 − 6.55log10 ( hBS
))log10
( ) + 45.5 + (35.46−1.1h
MS
)log10(
f
c
) −13.82log10
( hBS
) + 0. 7hMS
(5.50)
1000
where
h BS = the height of the base station
h MS = the height of the mobile station (m)
f c = the centre-frequency (MHz)
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