measurements at larger distances, e.g. beyond 200-300 m in UMi or in severely shadowed regions at
shorter distances. In UMa measurements were able to be made at least in the Aalborg location at
distances up to 1.24 km. An overview of the measurement and ray-tracing campaigns can be found
in the Appendix. In the following sections we outline the main observations per scenario with some
comparisons to the existing 3GPP models for below 6 GHz (e.g. [3GPP TR36.873]).
4.1 UMi Channel Characteristics
The LOS path loss in the bands of interest appears to follow Friis’ free space path loss model quite
well. Just as in lower bands, a higher path loss slope (or path loss exponent) is observed in NLOS
conditions. The shadow fading in the measurements appears to be similar to lower frequency bands,
while ray-tracing results show a much higher shadow fading (>10 dB) than measurements, due to
the larger dynamic range allowed in some ray tracing experiments.
In NLOS conditions at frequencies below 6.0 GHz, the RMS delay spread is typically modelled at
around 50-500 ns, the RMS azimuth angle spread of departure (from the AP) at around 10-30°, and
the RMS azimuth angle spread of arrival (at the UE) at around 50-80° [3GPP TR36.873]. There are
measurements of the delay spread above 6 GHz which indicate somewhat smaller ranges as the
frequency increases, and some measurements show the millimeter wave omnidirectional channel to be
highly directional in nature.
4.2 UMa Channel Characteristics
Similar to the UMi scenario, the LOS path loss behaves quite similar to free space path loss as
expected. For the NLOS path loss, the trends over frequency appear somewhat inconclusive across a
wide range of frequencies. The rate at which the loss increases with frequency does not appear to be
linear, as the rate is higher in the lower part of the spectrum. This could possibly be due to diffraction,
which is frequency dependent, being a more dominating propagation mechanism at the lower
frequencies. At higher frequencies reflections and scattering may be more predominant. Alternatively,
the trends could be biased by the lower dynamic range in the measurements at the higher frequencies.
More measurements are needed to understand the UMa channel.
From preliminary ray-tracing studies, the channel spreads in delay and angle appear to be weakly
dependent on the frequency and are generally 2-5 times smaller than in [3GPP TR36.873].
The cross-polar scattering in the ray-tracing results tends to increase (lower XPR) with increasing
frequency due to diffuse scattering.
4.3 InH Channel Characteristics
In LOS conditions, multiple reflections from walls, floor, and ceiling give rise to waveguiding.
Measurements in both office and shopping mall scenarios show that path loss exponents, based on a 1
m free space reference distance, are typically below 2, leading to more favorable path loss than
predicted by Friis’ free space loss formula. The strength of the waveguiding effect is variable and the
path loss exponent appears to increase very slightly with increasing frequency, possibly due to the
relation between the wavelength and surface roughness.
Measurements of the small scale channel properties such as angular spread and delay spread have
shown remarkable similarities between channels over a very wide frequency range. It appears as if the
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