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

WINNER D5.4 v. 1.4
A measurement campaign has been conducted in a metropolitan typical urban macro-cell (scenario C2),
with simultaneous measurements of the three links between a single mobile-station, and three sector
antenna arrays, one of them located just above average rooftop level and the other two sectors well above
roof-top level, see Section 5.2.5. No correlation was found between the two sites in the measurements.
However, this is believed to be due to measurement problems and we believe the true correlation between
sectors of the same cell is full. The geometry of the measurements where such that the angle β between
the base-stations was typically large as illustrated in Figure 4.4. In addition the base-station heights were
different. These measurements show that for metropolitan typical urban environments (scenario C2)
under the conditions stated the correlation is zero.
In the future it is possible to develop models the correlation is situations where it exists. It is likely that it
only exist in a few situations when β is small and the distances r 1 and r2
are close. This situation would
actually be preferable from the point of view of complexity of the channel generation in simulations. A
computationally efficient way of introducing such correlations is described by the following two
equations
and
( ) µ
0.5
( x,
y) = ( ∆r) ? ( x,
y) + ( x y)
~ 1
1
s R ξ , +
(4.39)
( ) µ
0.5
( x,
y) = ( ∆r) ? ( x,
y) + ( x y)
~ 2
2
s R ξ , + , respectively, (4.40)
1
2
where the random processes ξ ( x, y)
, ? ( x, y)
and ( x, y)
~1 ~2
s ( x,
y)
and s ( x,
y)
is introduced by the common random process ξ ( x, y)
T
{?
( x y) ? ( x,
y)
} = diag( c , K,
)
and
,
1
? are independent and the correlation between
c m
.Assuming
E (4.41)
1 1,T
2 2,T
{?
( x y) ? ( x,
y)
} E ? ( x,
y) ? ( x,
y)
{ } = diag( 1- c , K,
− )
E = 1 , (4.42)
this produces a cross-correlation of the form
E
,
1
{ ~ 1 2, T
0.5
0.5, T
s ( x,
y) ~ s ( x,
y)
} = ( ∆r) diag( c , , c ) R ( ∆r)
R K . (4.43)
A key question here is whether this correlation structure models the true cross-correlation accurately
enough or not. In the multi-cell measurements available now correlation was found between sites, see
Sections 5.2.5.1 and 9.3.1. For this reason the system level vectors of different sites will be modeled as
independent.
In the WINNER model as well as in SCM the shadow-fading is correlated with a correlation coefficient
of 0.5. The only reference known to the authors where inter-site correlation has been studied is [Maw92].
In this paper the cross-correlation between the log-normal-fading is approximated as 0.9
− θ / 200 where
θ is the angle between the two sites and seen from the MS. The model is based on measurements two
base-stations at 45 and 90 meter height, the distance to the two base-stations are 2-38 km and the
frequencies are in the 154-922 MHz range. These parameters are substantially different from the
measurements made in the WINNER project and we therefore chose to put neglect them.
4.2 Stationary-feeder scenarios B5
It should be noted that for the other prioritized scenarios WP5 have measurement data and improved
modelling of them is an ongoing effort while for the feeder scenarios this is not the case. In any case WP5
feels that the interim channel models are sufficiently good as a starting point for simulations and further
discussions. In stationary feeder both terminals are fixed, the channel modelling approach is clustered
delay-line modelling approach. Clustered delay line models for the first two sub-scenarios (B5a and B5b),
defined in Subsection 1.3.2.1.3, are defined in Section 4 based on the analysis below and we describe how
models for the B5c and B5d sub-scenarios could be obtained by modifying scenario B1 and C2,
respectively.
4.2.1 B5a LOS stationary feeder: rooftop-to-rooftop
The propagation scenario in the LOS measurements in [PT00] and [SCK05] is the most similar to ours,
although in [SCK05] the distance is very short. Therefore, we will base the propagation model mostly on
[PT00] for the parameters that are available from in that paper. Remaining parameters will be derived
from the other papers. Only a tapped delay-line model is provided. This scenario probably can be
characterized by a strong line of sight and single-bounce reflection as indicated in Figure 4.5. If the LOS
path is slightly obstructed, the influence of multi-path-related parameters will be strong, and far-away
1
m
c m
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