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

WINNER D5.4 v. 1.4
pdf as the double-azimuth-delay probability density function f ( φ , ϕ,
τ ). The joint functions f ( φ , ϕ,
τ )
and P ( φ , ϕ,
τ ) are mathematically intractable as it is a joint distribution of non-Gaussian random
variables. Hence, we can study the power azimuth-angle-delay spectrum, P ( φ , ϕ,
τ ). Under the
assumption that the power spectrum function of one domain is independent of partial information in other
domains, if ∆τ
is small enough such that the RMS delay spread of multipath components within ∆ τ is
very small and close to zero, while they are separated in azimuth-departure angle domain, we call P ~ ( φ)
as the zero-delay-spread cluster of departure (ZDSC_D). This defines cluster characteristics of multipath
components that are separated in azimuth angle of departure domain but have almost same delays.
Similarly with the power azimuth-arrival-angle-delay spectrum such that having the same argument about
having ∆ τ small enough such that the RMS delay spread of multipath components within ∆ τ is very
small and close to zero while they are separated in azimuth-arrival angles domain, we call P ~ ( ϕ)
as the
zero-delay-spread cluster of arrival (ZDSC_A). This defines cluster characteristics of multipath
components that are separated in azimuth-angle of arrival domain and have almost same delay. With the
argument discussed above we can say that:
4.1.4.1.3 Large-scale parameters
P
( φ ϕ,
τ ) ∝ P( φ) P( ϕ) P( τ )
P is a function of the RMS angle-
It is known that P ( φ)
is a function of the RMS angle-spreadσ φ , ( ϕ)
spreadσ , and ( τ )
, (4.29)
ϕ P is a function of the RMS delay spreadσ τ . For each power departure-azimuthdelay
spectrum and power arrival-azimuth-delay spectrum that represents a specific channel segment, the
sets ( σ , σ , σ ) are considered fixed but they change from channel segment to another with movement
φ
τ
ϕ
of the MS. Hence, these sets can be considered as random variables. Therefore, they can be described by
f σ , σ , σ . The marginal probability density function of each
joint probability density function as ( )
dispersion metric can be obtained as:
f
f
f
ϕ
φ
τ
( στ
) = ∫∫ f ( σ
ϕ
σ
φ
, στ
) dσφdσ
ϕ
( σ
φ
) = ∫∫ f ( σ
ϕ
σ
φ
, στ
) dστdσ
ϕ
( σ
ϕ
) = ∫∫ f ( σϕ
σ
φ
, στ
) dστdσ
ϕ
, (4.30)
, (4.31)
, (4.32)
In literature the distributions of these parameters are usually <strong>report</strong>ed as lognormal for some of outdoor
scenarios. To represent the channel characteristics, the sets ( σ , σ , σ ) must be selected randomly
while considering the correlation between them to represent their channel segment.
4.1.4.1.4 Bulk parameter cross-correlation
Generation of multipath component characteristics in teRMS of rays parameters, i.e., delays, angle of
departures and angle of arrivals are drawn from random number generators specified by probability
density functions of the corresponding parameters by combining the Gaussian distribution with the
transformation function g ( x)
, see Section 4.1.4.2 below. These distributions are functions of dispersion
metrics that are discussed in Section 3.1.1 earlier. These dispersion metrics might be correlated with each
other, with lognormal shadowing and cross-polarisation ratio. Thus, correlation has to be considered in
generation of dispersion metric and shadowing. For each link, the correlations between all large-scale
parameters are taken into account. In addition, the correlation of these parameters between two MS and
one BS (or one MS at two points in time) are modelled by considering the auto-correlation properties of
the large-scale parameters. However, the cross-correlation in the links between one MS and two BS are
set to zero in this model based on the discussion in Section 4.1.4.2.3.
4.1.4.1.5 Azimuth angle distributions of ZDSC
The mean departure angle of ZDSC_D and mean arrival angle of ZDSC_A can be located anywhere
within the azimuth-departure-angle domain or azimuth-arrival-angle domain. The departure (arrival)
angles of the rays within the ZDSC_D (ZDSC_A) are generated to satisfy certain angle-spreads within the
cluster. In order to reduce the complexity of the channel model the same angle-spreads of all ZDSC is
assumed. These angle-spreads may vary from scenario to another. In order to minimize the model
complexity, the angle spacing between rays within the cluster is considered fixed to satisfy a specific
angle-spread. The azimuth angles spacing of rays is predefined as an offset from a mean angle of the
φ
τ
ϕ
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