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

WINNER D5.4 v. 1.4
A path-loss model for system simulations is needed for considerably greater distances than generally
<strong>report</strong>ed in literature, and obtained from Helsinki PL measurements. Therefore, based on the widely
varying information available from existing literature on propagation at 5 GHz frequency range, we
propose to use 2 GHz COST231-Hata model with free-space correction to model path loss around 5 GHz.
A reasonable resemblance was achieved at least within 2 kilometer range with urban macrocellular
measurements in Helsinki.
5.5.5.4 RMS delay spread
Ref. [WHL94] presents wideband propagation measurements taken in the 1850-1990 MHz band with 10
MHz chip rate in flat rural, hilly rural and urban high-rise environments. In flat rural scenario typical
delay spreads are of the order of ~100 ns, whereas in urban high-rise cells median delay spread was ~700
ns. Typical delay spread values of 800-1200 ns in urban macrocellular environments at 1.8 GHz are
<strong>report</strong>ed in [AlPM02].
In comparison of path losses and delay spreads between 430 and 5750 MHz frequencies [Pa05] it was
found that the delay spread decreased at higher frequencies: in urban macrocellular environment the
median delay spread decreased from 700 to 300 ns. Smaller delay spreads at higher frequencies indicate
reflected signals were attenuated and fell below the 20 dB cutoff used for delay spread calculations. Also
results on microcellular environment <strong>report</strong>ed in [Bul03] show that RMS delay spreads were consistently
lower at 6 GHz compared to those at 2 GHz by factor of 0.86.
Somewhat contradictory conclusions have been <strong>report</strong>ed in [OTTH01], which presents path-loss and
delay spread results from Japanese urban metropolitan environment at 3 GHz, 8 GHz and 15 GHz
frequencies. In the measurements power delay profiles were recorded simultaneously for each of the three
frequencies in micro- and macrocellular scenarios. For multipath characterization 50 MHz bandwidth was
used, and 15 dB dynamic range was applied in delay spread calculations. Typical (median) RMS delay
spread values were ~100 ns, and maximum excess delays (50%) ~300 ns. Differences between
frequencies were found to be very small.
The following table summarizes the RMS delay spread and maximum excess delay statistics extracted
from urban macrocellular measurements in Helsinki city centre. Dynamic range of 20 dB was used.
10% 50% 90%
σ τ [ns] 85 265 532
Max excess delay [ns] 575 2210 3490
5.5.5.5 Angle-spread
In [PLN+99] directional wideband channel measurements at 2.1 GHz centre-frequency and 50 MHz
bandwidth in urban and suburban areas have been performed. It was found that in urban areas a BS
antenna installed at lamppost level lead to more severe azimuth spread than a BS at rooftop level.
Correlation between angle-spread and delay spread was low. In urban city environment the macrocellular
BS position was at 25 meters, which is slightly above surrounding rooftop levels. BS-MS distances ranges
from 20 to 360 meters. In suburban environment with low residential wooden houses the BS height was 7
meters, which was around the rooftop level of most the surrounding buildings. In this scenario BS-MS
distances were 50…510 meters. Typical azimuth spread values (50 precentile value in cdf) in urban
macrocellular environment were 7.6…11.8 degrees, with mean value of 9.9 degrees. For the same
environment typical delay delay spreads were 20…92 ns, with mean value of 56 ns. In suburban
measurements azimuth spread values 12.9…18.4 degrees with mean value of 15 degrees were obtained.
Corresponding delay spread values were 45…233 ns, with mean 119 ns.
In [KRB00] angle power distributions at the MS were measured in urban macrocellular environment in
Paris at 890 MHz. It was found that street canyons force the long-delayed waves to come from street
directions, but street crossings can cause additional signal components. For smaller delays local scatterers
contribute to power spectra. Propagation over the roofs was significant: typically 65% of energy was
incident with elevation angles larger than 10 degrees. In 1.8 GHz measurements <strong>report</strong>ed in [AlPM02]
median angle-spreads at BS are in the range 8-13 degrees.
In [KSL+02] elevation angle distributions at the mobile station in different radio propagation
environments have been <strong>report</strong>ed at 2.15 GHz centre-frequency. Results show that in non-line-of-sight
situations, the power distribution in elevation has a shape of a double-sided exponential function, with
different slopes in the negative and positive sides of the peak. The slopes and the peak elevation angle
depend in the environment and BS antenna height. In urban macrocells mean elevation angles of arrival
are ~7…14 degrees, with standard deviations of 12…18 degrees.
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