S. L. H. Nguyen et al., “Comparing Radio Propagation Channels Between 28 and 140 GHz Bands in a Shopping Mall,”
to be published in 2018 European Conference on Antennas and Propagation (EuCAP), London, UK, April 2018.

Comparing Radio Propagation Channels Between
28 and 140 GHz Bands in a Shopping Mall
Sinh L. H. Nguyen† , Jan Järveläinen†‡ , Aki Karttunen† , Katsuyuki Haneda† , and Jyri Putkonen∗
Aalto University, School of Electrical and Engineering, Finland
{sinh.nguyen, katsuyuki.haneda, aki.karttunen}@aalto.fi
‡
Premix Oy, Finland
jan.jarvelainen@premixgroup.com
∗
Nokia Bell Labs, Finland
jyri.putkonen@nokia-bell-labs.com

I. I NTRODUCTION
Millimeter-wave bands, referred as frequency bands from
30 GHz−300 GHz, have been exploited for 5G radio communications in recent years [1], [2]. However, the majority
of the propagation channel studies and experiments has been
focused only to bands up to 100 GHz [3]–[7]. While above-100
GHz bands experience higher path loss, at the same time wider
unused bandwidth chunks are available in those bands, making
them also possible candidates for future wireless systems. For
example, in Finland a bandwidth of 7.5 GHz (141 − 148.5
GHz) in D-band is currently unused and could be exploited
for future fixed and mobile radio communications [8].
Shopping mall is among the scenarios where mobile broadband experiences are expected to be supported in 5G, i.e.,
“great service in a crowd” [9]. Propagation channels in the
shopping mall environment were studied in [10] at 28 GHz
band, and in [11], [12] for 15, 28, 60, and 73 GHz bands.
Literature on the channel measurements at above 100 GHz
frequencies is in general very limited, and has not been found
for the shopping mall environment in particular. Only one previous work on very short range indoor pathloss measurement
has been found in the literature, where line-of-sight (LOS)
pathloss was measured as the antenna separation varied from
20 to 180 cm [13].
In this paper, for the first time in the literature we report
microcell directional channel measurements at 140 GHz for

a large indoor shopping mall environment. Furthermore, we
compare the 140 GHz channel characteristics with its counterparts at 28 GHz using the data measured at the same links
in the same manner. The wideband (4 GHz) and directional
measurements and data processing were conducted in such
a way allowing us to make a fair comparison of large- and
small- scale channel parameters between the two bands. The
similarity and difference in pathloss, and large- and smallscale parameters between the two bands are then analyzed to
investigate the possibility of using the 140 GHz frequencies
for future mobile radio communications.
II. M EASUREMENT SETUP AND ENVIRONMENT
The wideband directional channel measurements were performed using the same approach reported in [11], [14], [15].
Specifically, two similar setup radio channel sounders were
used to perform channel measurements in the 28 and 140 GHz
frequency ranges, where the RF signals were generated using
the Ka-band (26.5 − 40 GHz) and D-band (110 − 170 GHz)
up- and down-converters, respectively. The schematic diagram
of the measurement system is shown in Fig. 1. The details of
the channel sounder can be found in [11].
Rx horn antenna
(19 dBi)
Waveguide

Tx bicone antenna
(2 dBi)
RF signal
Up
converter

Abstract—In this paper, we compare the radio propagation
channels characteristics between 28 and 140 GHz bands based
on the wideband (several GHz) and directional channel sounding
in a shopping mall environment. The measurements and data
processing are conducted in such a way to meet requirements for
a fair comparison of large- and small- scale channel parameters
between the two bands. Our results reveal that there is high
spatial-temporal correlation between 28 and 140 GHz channels,
similar numbers of strong multipath components, and only small
variations in the large-scale parameters between the two bands.
Furthermore, when including the weak paths there are higher
total numbers of clusters and paths in 28 GHz as compared to
those in 140 GHz bands. With these similarities, it would be very
interesting to investigate the potentials of using 140 GHz band
in the future mobile radio communications.
Index Terms—5G, 28 GHz, 140 GHz, Channel modelling, Dband, Millimeter-wave.

Down
converter

arXiv:1712.09438v1 [] 26 Dec 2017

†

Rotator

30 dB
amp

Tripod
O/E

Control
PC

Vector network
10 MHz sync
analyzer
Signal
Generator
LO signal
IF signal

Optical fiber
cable 200m

Splitter
E/O

Fig. 1. Channel sounding system: Tx (Rx) includes a frequency multiplier
(factor of 2 in 28-GHz and 12 in 140-GHz bands) and a mixer for upconverting (down-converting) the IF (RF) signal.

The venue for the shopping mall measurements was the
Sello shopping mall in Leppävaara, Espoo, Finland, presented

Tx7

Tx5

Tx20
Tx21

Tx19
Tx4
Tx17

Tx22

Tx18

Tx2

Tx23
Tx12

50
Tx17

Rx1
Tx1

40
30

Tx13
Tx16

20

Tx24

Tx15
10
Tx14
0
10
-10

Fig. 2. 3-D map of the Tx and Rx positions in the 3rd floor of the Sello shopping mall in the 140-GHz measurement, overlaid with the 3-D point cloud
model of the environment. The green triangles present the Tx locations that were also measured at 28 GHz in the same day in November 2016; the yellow
triangles present the Tx locations that were also measured at 28 GHz but in March 2015; the orange triangles present the Tx locations that were measured in
140 GHz band only.

measurements in [11], [14].
To compare 140 GHz channels with its 28 GHz counterpart,
8 links (5 LOS and 3 obstructed LOS) that were measured
in the same day are used for the comparison. As can be seen
from Table II and Fig. 4, measurement specifications including
bandwidth and antenna patterns were ensured to meet the
requirements for comparability of channel’s parameters across
different frequencies, as defined in [6].

TABLE II
C OMPARABILITY BETWEEN TWO FREQUENCY BANDS .

Fig. 3. Photo from the Sello shopping mall.

28-GHz band
140-GHz band
28.5 GHz
143.1 GHz
4 GHz
4 GHz
2 dBm
−7 dBm
123 dB
130 dB
1.9 /1.9 m
3 − 65 m
horn, 19 dBi, 10◦ az./40◦ el. HPBW
bicone, 0 dBi, 60◦ el. HPBW

in Fig. 3. The shopping mall is a modern, four-story building
with a large open space in the middle and approximate
dimensions of 120×70 m2 . The floorplan of the channel
measurements are shown in Fig. 2. In total, 18 Tx antenna
locations were measured at 140 GHz, with antenna heights
of 1.9 m and the Tx-Rx distance ranging from 3 to 65 m,
approximately. The Tx were moved a long the corridor and
around open space in the middle of the shopping mall. In
three Tx locations, the LOS path was obstructed by the pillar
or the escalator. The antenna locations were chosen such that
human blockage could be avoided in order to maintain the
repeatability of the measurements at both frequency bands.
At each Tx location, the Rx horn antenna was rotated in the
azimuth plane with 5◦ step, as similarly done in the directional

Comment
3
Approximately (in the same day)
3
3
0.25 ns
10◦ in azimuth, 40◦ in elevation
3
3

Elevation cut

Azimuth cut
5

0

0
-5

Normalized gain (dB)

Parameter
Center frequency
Bandwidth
Transmit power
PDP dynamic range
Tx / Rx height
Link distance range
Rx antenna
Tx antenna

Requirement
Same environment
Same measurement time
Same antenna locations
Comparable antenna patterns
Equal delay resolution
Equal spatial resolution
Same post processing method
Same power range

Normalized gain (dB)

TABLE I
S UMMARY OF THE MEASUREMENTS .

-10

-20

-30
28.5 GHz
143 GHz

-40

-10
-15
-20
-25
-30
-35

28.5 GHz
143 GHz

-40
-45

-20

0

20

-20

-10

0

10

20

Fig. 4. Comparison of Rx radiation patterns in (left) azimuth plane and (right)
elevation plane between 28-GHz and 140-GHz bands.

Link Tx18Rx1

Link Tx17Rx1
90

90

-80dB

120

60

Link Tx19Rx1
90

-100dB

120

60

Link Tx20Rx1
90

-90dB

120

60

-90dB

120

60

-100dB

-100dB

-110dB

-100dB

-110dB

30

150

30

150

-110dB
30

150

30

150

-120dB

-120dB

-120dB

-120dB

-130dB
180

0

210

180

210

330

240

0

240

300

0

210

240

300

(a)

60

210

330

300

240

300
270

(b)

(c)
Link Tx23Rx1
90

-90dB

120

(d)
Link Tx24Rx1
90

-80dB

120

60

-100dB

0

270

Link Tx22Rx1
90

-90dB

120

180

330

270

Link Tx21Rx1
90

180

330

270

-130dB

60

-60dB

120

60

-100dB

-80dB

-100dB
-110dB

-110dB

150

30

150

30

-120dB

-130dB

-100dB

150

0

210

330

300

-120dB

180

0

210

330

240

30

-120dB

-130dB

180

240

150

30

-120dB

300

180

0

210

180

330

240

0

210

330

300

240

300

270

270

270

270

(e)

(f)

(g)

(h)

Fig. 5. Comparison of power-angular profiles between 28 GHz (dashed blue) and 140 GHz (solid red) for Tx positions from ((a) 17 to (h) 24. Tx positions
17, 19, 21, 23, 24 are in LOS and the rest are in obstructed LOS conditions.

III. C OMPARISON OF LARGE - SCALE PARAMETERS

From the measured power angular delay profiles (PADPs),
the multipath components (MPCs) in each measurement were
extracted using the peak search algorithm in [14]. The peak
detection algorithm is based on the assumption that the channel
is deterministic for at least the strong MPCs, i.e., the arriving
signals from discrete specular reflectors are completely resolvable either in delay or angular domain [16]. The assumption is
justified by the very wide channel measurement bandwidth of 4
GHz and narrow azimuth beamwidth of 10◦ of the receive horn
antennas at both measured frequencies. The azimuth angle of
arrival (AoA) and amplitude of each MPC are calculated using
the receive antenna pattern and subtracting the corresponding
antenna gain from the peak’s amplitude [14].

(a)

25

100
28 GHz
140 GHz

28 GHz
140 GHz

20

Number of MPCs

Number of MPCs

80

60

40

15

10

5

20

0

0
18

20

Tx position

(a)

22

24

18

20

22

24

Tx position

(b)

Fig. 7. Number of detected specular paths within a) 30-dB threshold and
b) 15-dB threshold in Sello shopping mall. The corresponding mean values
plotted with horizontal dotted lines
(b)
Fig. 6. PADPs of link Tx17-Rx1 and detected peaks (red dots) within 30-dB
range in (a) 28 GHz and (b) 140 GHz measurements.

One example of the PADPs and peak search is presented in
Fig. 6, which shows the measured channel for the Tx position
17 (LOS). It can be noticed that many deterministic paths

Delay spread [ns]

40
28 GHz
140 GHz
30
20
10
0

0

5

10

15

20

25

30

35

25

30

35

Link distance [m]

(a)

Azimuth spread [ ]

50
28 GHz
140 GHz

°

occur in both frequency bands. As depicted in Figs. 5 and
7, there are clearly more paths at 28 GHz than at 140 GHz
when considering a 30-dB threshold seen from the strongest
path amplitude. However, when 15-dB threshold is used, the
number of (strong) paths is very similar between the two bands
for all links, expect link Tx18-Rx1, which is OLOS. This
similarity in the multipath richness between the two bands,
especially in this indoor environment, can be explained by the
fact that the environment consists of many surfaces considered
smooth even at 140 GHz.
From the detected MPCs, omni-direction pathloss, delay and
angular spreads have been calculated for 28 and 140 GHz.
Due to the low dynamic range at 140 GHz, a 30 dB threshold
has been used. The results are presented in Figs. 8 and 9, and
Table IV. It can be seen that the average delay spread is almost
identical for the both frequency bands, and the azimuth spread
is 10% higher at 28 GHz. The small difference between the
bands can be explained by the fact that the most significant
paths are found in both bands. When comparing link by link,
noticeably higher DS and AS can be observed in 28 GHz in
the obstructed LOS link Tx18-Rx1.

40
30
20
10

0

5

10

15

20

Link distance [m]

(b)
Fig. 9. (a) Delay spread and (b) azimuth spread in the shopping mall. Mean
values plotted with dotted lines.

28 GHz fspl
28 GHz meas.
140 GHz fspl
140 GHz meas.

110

Path Loss [dB]

100

TABLE IV
M EAN OF DELAY AND AZIMUTH SPREADS OVER ALL COMMON T X -R X
LINKS IN THE SHOPPING MALL AT 28 AND 140 GH Z .

90

80

Frequency

Delay spread [ns]

Azimuth spread [◦ ]

28 GHz
140 GHz

19
19

33
29

70
10

0

1

10
Link Distance [m]

10

IV. C OMPARING NUMBER OF CLUSTERS AND
INTER - CLUSTER CHARACTERISTICS

2

Fig. 8. Measured omni-direction pathloss at 28 GHz (dots) and 140 GHz
(triangles) bands. The solid lines show the free-space pathloss (fspl) at
corresponding frequencies.

Fitting the measured omni-directional pathloss data of each
of the two bands to the pathloss model equation
P L(d) = 10A log10 (d/1m) + B + N (0, σ 2 ),

(1)

we obtain the model parameters shown in Table III. It can be
seen from Fig. 8 and Table III that except some additional fspl
at 140 GHz, the slope and variations of the pathloss data of
two bands are similar.
TABLE III
PATHLOSS MODEL PARAMETERS IN THE SHOPPING MALL IN 28-GH Z AND
140-GH Z BANDS .
Parameter

28 GHz

140 GHz

A
B
σ

2.10
59.16
2.85

2.22
70.77
2.94

To obtain cluster parameters for each link of the two
bands, a hierarchical clustering algorithm [14] was used with
the detected MPCs. For the purpose of comparing cluster
model parameters between the two bands, the same multipath
component distance (MCD) threshold of 30 dB was used
for both 28 and 140 GHz band. Denoting the number of
clusters and the number of MPCs per cluster for a given link
as N and M , respectively, Table V presents the mean and
standard deviation values of N and M in the 28 and 140 GHz
measurements. It can be observed from the results that both
the number of clusters and the number of paths per cluster
are higher in the 28 GHz bands as expected from the higher
total number of detected paths when higher threshold value
is used. Comparing to the parameters adopted in 3GPP New
Radio (NR) model TR 38.901 for above 6 GHz Indoor Office
environment [4], that is, 15 clusters for LOS and 19for nonline-of-sight (NLOS) (each of them has 20 MPCs) scenarios,
our results in both frequency bands appear to have smaller
number of clusters and MPCs per cluster.
As far as the relation between the cluster power and cluster
propagation distance is concerned, Fig. 10 shows the empirical data obtained from the measurements and our clustering

TABLE V
M EAN AND STANDARD DEVIATION OF THE NUMBER OF CLUSTERS N AND
THE NUMBER OF MPC S PER CLUSTER M FOR SHOPPING MALL SCENARIO .
Parameter

28-GHz band

140-GHz band

N

µ
σ

7.9
3.6

5.9
2.1

M

µ
σ

5.4
6.0

3.8
2.5

Pn
= exp[−(φn /σ)2 ],
max(Pn )

process. Linear regression fits well with the empirical data in
both bands. The fitting model can be expressed as
(2)

Pc = A log10 (dc ) + B,

where Pc and dc are the cluster power in dB and cluster propagation distance in m, respectively. A simple liner regression
provides that (A, B) is equal to (−30.5, −58.0) in the 28-GHz
band and equal to (−24.8, −78.1) in the 140-GHz band.
-70
Powers vs. distance - 28GHz
Linear fit - 28GHz
Powers vs. distance - 140GHz
Linear fit - 140GHz

-80

Power [dB]

-90
-100
-110
-120
-130
0.6

0.8

1

1.2

1.4

1.6

1.8

log 10 (d) [m]

Fig. 10. Empirical cluster power [dB] versus cluster distance [log10 (m)],
and the linear fit at 28 and 140 GHz.

TABLE VI
M ODEL PARAMETERS AND FITTING ERROR FOR THE COMPOSITE PAS IN
AZIMUTH OF ALL CLUSTERS .
Model

28-GHz band

140-GHz band

Gaussian

[◦ ]

σ
RMSE

17.9
0.011

18.0
0.005

Von Mises

κ [◦ ]
RMSE

8.2
0.086

8.2
0.085

for the normalized cluster power Pn /max(Pn ) versus offset
AoA φn to both Gaussian and Von Mises distributions are

The generation of the cluster offset angle in 3GPP is based
on the distribution of the composite power angular spectrum
(PAS), and the AoAs can be determined via inverse Gaussian
[4] or inverse wrapped Gaussian functions. The latter can
be closely approximated by Von Mises distribution that is
mathematically simpler and more tractable. The fitting models

(3)

eκ cos φn
Pn
=
,
(4)
max(Pn )
2πI0 (κ)
respectively, where I0 (κ) is the modified Bessel function of
order 0, 1 ≤ n ≤ N is the clustering index, N is the total
number of clusters. The results in Table VI show that the
model parameters are similar between 28 and 140 GHz bands.
ACKNOWLEDGEMENT
The research leading to the results presented in this paper
received funding from Nokia Bell Labs, Finland.
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