Measurement and Characterization of Various Outdoor 60 GHz
Diffracted and Scattered Paths
Jonathan S. Lu1,2, Patrick Cabrol2, Daniel Steinbach2 and Ravikumar V. Pragada2
Polytechnic Institute of New York University1, InterDigital Communications LLC2
firstname.lastname@example.org, Patrick.Cabrol@interdigital.com, Daniel.Steinbach@interdigital.com and
Abstract— This paper investigates diffracted and scattered waves
in unlicensed millimeter wave mobile-to-mobile, access and
backhaul radio links. Narrowband 60 GHz measurements of
diffraction at building corners, and scattering by a car, lamppost
and building, as well as blocking by humans are presented. Semi-
analytical corner diffraction and human blocking models are
proposed and verified based on the measurements. Analysis of
the diffraction and scattering shows that the contributions from
vehicular and lamppost scattered paths can be dominant
compared to corner diffracted paths. Measurements also show
that the majority of power from building scattering arrives in
and near the horizontal plane containing the transmit and
Keywords—60 GHz; Backhaul; Diffraction; Millimeter Wave;
mmW; Mobile-to-Mobile; IEEE 802.11ad; IEEE 802.11aj; NLOS;
The 57–64 GHz millimeter wave (mmW) unlicensed band,
also known as the 60 GHz band, allows for multi-gigabit data
rates  with high spatial reuse. This has prompted the
attention of short-range wireless personal area networks
(WPAN) standards (e.g., Wireless HD, IEEE 802.15.3c and
ECMA 387), and wireless local-area networks (WLAN)
standards (e.g., WiGIG, IEEE 802.11ad and IEEE 802.11aj).
Many indoor applications have been proposed, such as indoor
cable-replacement for home and office multimedia streaming.
Outdoor applications have also gained popularity. Currently
backhaul is the predominant point-to-point outdoor use-case
for mmW frequencies with the focus slowly moving towards
mobile broadband systems. The 802.11ad standard allows for
multiple simultaneous direct mobile-to-mobile
communications . It is envisioned that in mmW mobile
wireless systems, mmW cells can be deployed utilizing
existing street furniture, building corners or building surfaces
avoiding the need for expensive dedicated mmW cell towers.
There is a plethora of literature summarized in ,  on
the wideband and narrowband channel parameters of 60 GHz
indoor links. In comparison, there is a smaller amount of
applicable literature ,  on the channel parameters of 60
GHz outdoor radio links and even fewer on the site-specific
interactions with common outdoor radio link obstructions (e.g.,
buildings and cars). In  and , it was found that there was
large variability in the channel parameters due to these site-
specific features. Understanding the strong dependence of the
channel parameters on these features requires further
investigation into the propagation characteristics of the
Whether a mmW system has sufficient SNR for a non-line-
of-sight (NLOS) link where one end of the radio link is
shadowed is dependent on the rays propagating around and
through the obstruction. For shadowing by a building,
transmission loss through building materials at 60 GHz is very
high , so it is expected that the diffraction at the building
corner and scattering from objects near the corner will be the
dominant modes of propagation. Diffraction of simple objects
such as wooden and metal blocks  has been studied, but to
the best of the authors’ knowledge, there are no 60 GHz
measurements characterizing building corner diffraction.
Therefore, we have made measurements on corner diffraction
and found that an absorbing screen diffraction coefficient best
models our measurements.
For human shadowing, significant fades up to 50 dB 
have been observed. Thus human blockers must be accounted
for in RF prediction tools. Human blockers have been modeled
as finite absorbing screens , , and water cylinders .
Verification of these models has generally only been done for a
single mobile-to-mobile blocker scenario. In this work, we
further verify the absorbing screen model for multiple humans
blocking a mobile-to-mobile and a single human blocking an
access link using uniform theory of diffraction (UTD) and
For line-of-sight (LOS) communications, propagation paths
other than the LOS path may need to be used because of
temporary obstructions such as the aforementioned human
blocking. In , it was found that NLOS paths near the LOS
path generally had smaller delay spread and less loss relative to
the LOS. These NLOS paths may arise from scattering from
lamppost and other street furniture. Similarly for NLOS
communications caused by building shadowing, this street
furniture may give significant contributions for turning a
corner as observed in UHF communications . We have
therefore performed a 60 GHz empirical study on vehicular,
lamppost and building scattering.
Section II describes our measurement setup and scenarios.
Simple diffraction models used to compare with our
measurements are given in Section III. The measurements are
presented and analyzed, and compared with the models of
Section II in Section IV.
2013 IEEE Military Communications Conference
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2013 IEEE Military Communications Conference
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II. MEASUREMENT SETUP AND PROCEDURE
For all of our 60 GHz measurement scenarios, the same
measurement equipment was used to record the received
power. In the individual scenarios, the antenna heights and
positioning varied as discussed below.
A. Measurement Equipment Setup
A diagram of our 60 GHz measurement equipment setup is
shown in Fig. 1. In the transmit system (TX), the SMF100A
microwave signal generator provides a 10 GHz sine wave to
the SMZ90 frequency multiplier, which multiplies the
frequency by six. The resulting 60 GHz signal then travels
through a straight section waveguide to the V-band horn
antenna with 24 dBi of gain and an 11 degree 3 dB beamwidth
whose normalized antenna pattern is shown in Fig. 2. In the
receive system (RX), the signal is received with an identical
horn antenna that is connected to the N12-3387 low noise
amplifier (LNA) with a straight waveguide section. The
amplified signal is sent to the FS-Z90 harmonic mixer where it
is down-converted and captured on the FSQ26 vector signal
B. Measurements from Building, Car, and Lamppost
To perform outdoor measurements on buildings, cars, and
lampposts shown in Fig. 3, the transmit (TX) and receive (RX)
systems illustrated in Fig. 1, were each placed on push carts.
To accurately point the antennas, the antennas were placed on
pan-tilt motors of 0.0032� angle resolution, which were
attached to the carts. Laptops on both carts ran a C++ program
that was developed to control the motors, query the VSA for
the received signal power and store measurement data.
The antennas’ heights hTX and hRX relative to the ground for
these measurement scenarios were 1.33 m and characterize a
mobile-to-mobile radio scenario. Because the building
scattering measurements were performed for sufficiently short
link lengths in which the contribution from ground reflections
was severely attenuated by the antenna pattern, these
measurements should also apply to backhaul radio links. To
apply the diffraction results to access links, an additional
cosine angle dependence should be included  to account for
the oblique incidence caused by the height difference.
1) Building Corner: To investigate the path loss for a NLOS
link in which the RX is shadowed by a building, diffraction
measurements around two different corners were recorded.
The geometries of the corners are shown in Fig. 4. The first
corner considered was composed of concrete. The TX cart was
placed so that the TX distance from the corner rTX = 3.75 m
and �’ = 18 degrees. The RX was moved in an arc in the
shadowed region. The radius of the arc which is the distance
to the corner rRX = 2.8 m. Measurements were recorded for
angles � = 200 to 260 degrees at intervals of 10 degrees.
Measurements were also performed on another corner
shown in Fig. 3.a, composed of concrete with windows located
near the corner. The TX cart was placed so that rTX = 6.1 m and
�’ = 10 degrees. The RX was again moved in an arc with
radius rRX = 4.0 m in the shadow region. Measurements were
recorded for � = 200 to 260 degrees at intervals of 15 degrees.
Figure 1. Block diagram of 60 GHz measurement setup
Figure 2. H-Plane and E-Plane normalized antenna gains.
Figure 3. (a) Corner 2, (b) Car, (c) Lamppost and (d) Building
Figure 4. Diffraction around a building corner.
2) Car: Vehicular scattering measurements on a 2006 Subaru
Forrestor shown in Fig. 3.b, were recorded in an empty
parking lot. The TX antenna was placed at distance rTX = 23 m
from the car. The TX antenna bore sight was centered on the
side of the car and was normal (�i = 0 degrees) to the car’s
surface. Measurements were recorded as the RX antenna was
moved in an arc of approximate radius rRX = 23 m, so that the
scattering angle �s relative to the normal of the car surface,
spanned 14 to 75 degrees.
3) Lamp Post: Power measurements on an isolated 3.7 m high
lampost shown in Fig. 3.c, with a square 0.1 m x 0.1 m cross
section were performed. The TX antenna was placed at a
distance rTX = 5 m from the lamppost. Measurements were
recorded as the RX antenna was moved in an arc of radius rRX
= 5.5 m around the lampost so that the angle between the
incident and scattered ray �s spanned 7 to 151 degrees.
4) Building Surface: To investigate the reflection/scattering of
features on a building surface, power angle profile
measurements from a 4-story office building shown in Fig.
3.d, were performed. The TX and RX antennas were placed so
that they were separated from each other by 8 m, and were 8.5
m from the building surface. Using the pan-tilt motors the TX
antenna illuminated different portions of the building surface.
For each portion of the building surface, the RX antenna
illuminated the same surface, so as to measure the received
power from that surface.
C. Human Blocking Measurements
Human blocking measurements were performed for mobile
to mobile and access link scenarios. These measurements are
later compared with predictions found from assuming the
blockers are absorbing screens and then using UTD and
physical optics to compute the diffraction loss.
1) Mobile to Mobile: In mobile to mobile communications the
TX and RX antennas are typically at the same height or lower
than normal human height. From , the majority of human
blocking cases involved three blockers at most. Thus, we
investigated two and three human blocking scenarios of a 7 m
LOS link. The antenna heights were hTX = hRX = 1 m. A more
detailed presentation of the setup and results is found in .
2) Access: For office or outdoor access radio links, the TX
antennas are typically located on ceilings, light posts, etc.,
above human height. To investigate this radio scenario, one
human blocking measurements of a 7 m LOS link were
performed. The antenna heights were hTX = 2.65 m and hRX =
0.9 m. Measurements were recorded as the human blocker
moved from the TX toward the RX antenna. During the entire
experiment, the human blocker’s body faced the RX antenna
and was centered on the direct line between the TX and RX
For each of the mobile-to-mobile and access link human
blocking configurations, five measurements were recorded
over a 5 second time period. These measurements were then
time-averaged in an attempt to mitigate the inadverdent
movement of the human blockers.
III. DIFFRACTION FROM SINGLE AND MULTIPLE EDGES
A diffracting corner is modeled as a conducting right-angle
wedge and an absorbing screen with a knife-edge in our
comparison with measurements. Human blockers are modeled
as semi-infinite absorbing screens with knife-edges. The
following sub-sections give expressions for the path gain and
diffraction loss around a conducting wedge, and single and
multiple absorbing screens.
A. Diffraction Around a Single Edge
The received power PR in watts from diffraction around a
vertical edge  can be expressed in the form
1 2 1 2
4 ( ) cosR T RX TX
D r rP P G G
r r r r
� � +
Here PT is the transmitted power in watts, and GRX and GTX are
the antenna gains of the TX and RX antennas, respectively. � is
the wavelength in meters, � and �’ are the angles in radians
defined in Fig. 4, �/2 - � is the acute angle the incident wave
makes with the edge in radians, and D(�, �’) is the diffraction
coefficient. Note that when � = 0, the incident wave is incident
normal to the edge. r1 and r2 are the distances of the TX and
RX antennas to the edge in meters, respectively. The received
power can be separated into two terms. The first term is the
LOS power along the diffracted path. The second term in the
square bracket is the diffraction loss incurred from diffracting
around the corner.
For a semi-infinite absorbing screen with a knife edge
corner, the UTD expression for D(�, �’) is
( ) 2 1 cos( ) 2 2
S S SD f jg
θ π ππ
� � � �+
= − +
Here � = � + �’ - � as seen in Fig. 4, and f, g, and S are defined
in [12, chapter 5].
For a conducting right angle wedge corner with E-field
parallel to the edge, the geometric theory of diffraction (GTD)
diffraction coefficient is expressed as
( ) 1 ( ) ( ), cot cot
3 33 2
( ) ( ) cot cot
π ϕ ϕ π ϕ ϕϕ ϕ
π ϕ ϕ π ϕ ϕ
− � + − + +
� � � �
′ = +
− − − + �
� � � �
B. Diffraction Around Multiple Absorbing Screens
To compute the diffraction loss, defined as free-space
power to diffracted power, from an arbitrary number of screens
parallel to the y = 0 plane, we use a physical optics method
developed by Piazzi -. This method is based on the
same principles of physical optics used in .
Assuming a) the knife-edges are of infinite length and are
parallel, and b) the additional diffraction loss for a point source
on a plane that is perpendicular to the screens is the same as
that for a line source that is parallel to the screens and
intersects the plane at the source point, the physical optics
description of diffraction around an absorbing screen is
expressed as multiple integrations in the x–z planes containing
the absorbing screens. The integrations in the coordinate along
a z-plane knife-edge can be approximated analytically so that
we are left with integration in the x-coordinate away from the
knife-edges. This is seen in the following expression for the
magnetic field H(xn+1, yn+1) in the plane containing the n + 1
absorbing screen :
( ) ( )/ 41 1, ,2
n n n n n
k eH x y e H x y dx
Here � is the distance from the secondary source point (xn, yn)
on plane x = xn to receiver point (xn+1, yn+1) on plane x = xn+1,
and k is the free-space wave number. The field on plane x = xn
containing the nth screen is given by H(xn, yn). To arrive at an
expression with multiple integrals, we substitute H(xn, yn) in (4)
with H(xn-1, yn-1), which is the field on plane x = xn-1 containing
the n - 1 screen and can similarly be written in integral form.
To predict the diffracted power from multiple screens, the
integrals must be carried out numerically. The integral in (4)
must be terminated with finite upper and lower limits (for the
right and left sides of the screen), and the integration must be
replaced by a discrete summation. The Piazzi method involves
simple linear approximations of the amplitude and phase and
introduces a smoothing procedure that uses a Kaiser-Bessel
function to terminate the integration without introducing
spurious diffraction –.
IV. RESULTS AND ANALYSIS
The recorded measurements are presented and compared
with theoretical models in this section.
A. Building Corner Diffraction
The magnitude of the diffraction coefficient values are
computed from building corner measurements using (1), and
are plotted in dB versus � = � + �’ - � in Fig. 5. Also plotted
are the UTD absorbing screen diffraction coefficient (2) and
the conducting GTD right-angle wedge diffraction coefficients
(3) for �’ = 10 and 18 degrees. As seen in Fig. 5, the
conducting wedge gives a pessimistic prediction to the
diffraction coefficient, while the absorbing screen gives a more
reasonable prediction. To quantify the accuracy we define the
error as the predicted diffraction coefficient magnitude in dB
minus the measured. The absorbing screen diffraction
coefficient for �’ = 10 and 18 degrees gives mean errors of -1
and 2.79 dB, respectively. The standard deviations of error are
1.56 and 2.6 dB respectively.
-70 -60 -50 -40 -30 -20 -10 0
Corner 1 Measurements φ' = 18 degrees
Corner 2 Measurements φ' = 10 degrees
Conducting Wedge φ' = 18 degrees
Conducting Wedge φ' = 10 degrees
Figure 5. Comparison of diffraction coefficient measurements
and theoretical diffraction coefficients.
0 20 40 60 80 100 120 140 160
Scattering Angle θs, ψs [degrees]
Figure 6. Scattering loss from a car with incident angle �i = 0
degrees, and lamppost.
From , the structure of a diffracting corner has a
significant impact on the diffraction coefficient of the corner.
For example, rays traveling through the windows near to a
corner may have a larger contribution to the received power
than those diffracted by the corner. In our measurements, we
did not see this effect probably because the metal blinds of the
windows near the corner shown in Fig. 3.c were drawn down.
B. Scattering from Car and Lampost
The scattering losses from a car (blue triangles) are plotted
versus scattering angle �s in Fig. 6. The scattering loss is the
received power normalized to the free space power over the
scattering path length rTX + rRX. As expected, the scattering loss
is smaller nearer to the specular direction �s = 0 degrees.
The scattering losses from a lamppost (red squares) are
plotted versus the scattering angle �s between the incident and
reflected waves in Fig. 6. Again, the scattering loss is the
received power normalized to the free space power over the
scattering path length rTX + rRX. The low loss at 144 degrees on
the lamppost curve corresponds to specular reflection from the
lamppost’s rectangular cross section.
C. Building Shadowing; Diffraction vs. Scattering
It is interesting to compare the contributions from scattered
rays and diffracted rays for the case of a NLOS mmW link in
which the TX and RX are located on the sidewalks of adjacent
sides of a building, and rTX = rRX = 23m from the corner. The
diffraction angle � is then close to -90 degrees, so that the
absorbing screen diffraction coefficient magnitude is
approximately 40 dB. Accounting for the distance dependence,
the diffraction loss (square brackets of (1)) is then
approximately 50 dB. Now assume there is a car near the
corner and the car is parked parallel to the building surface.
Using our measurements from Fig. 6, the scattering loss is then
on the order of 30 dB. For this case the vehicular scattering
gives a much larger contribution than the corner diffraction.
Now consider a similar case, but with a square cross-
section lamppost near the corner instead of a car and the RX
and TX distances to the corner and lamppost are rTX = 5 m and
rRX = 5.5 m, respectively. The diffraction loss for the corner is
44 dB, while the scattering loss from Fig. 6, will be less than
40 dB. Depending on how the lamppost is oriented, the
scattering loss can be on the order of 12 dB. Thus, for this
scenario, the contribution from the lamppost is expected to be
To extend these results to more general radio scenarios, we
would have to know the distance dependence of the received
power from the car and lamppost. Though, if we assume they
have similar distance dependence to corner diffraction, we can
conclude that the scattering will usually be dominant for the
short TX-RX separations under consideration.
D. Building Scattering
The received power angular profile minus the LOS power
in dBm at the RX antenna is plotted in Fig. 7. It can be seen
that the majority of power arrives in the horizontal plane
(elevation angle = 0 degrees) containing the TX and RX
antennas at 0, 25 and 40 degrees. The 0 and 40 degree humps
correspond to columns on the building surface, while the 25
degree hump corresponds to specular reflection. Other humps
outside this plane correspond to window sills and a triangular
prism feature on the building surface. Other results not shown
give similar results. These 60 GHz results are similar to UHF
band results presented in  and , where the features on
the building surface (e.g., balconies and columns) contributed
significantly to the received power angle profile.
E. Mobile to Mobile Link Human Blocking
In our measurements, the transmission loss through a single
blocker is greater than 50 dB, and reflection and scattering
from nearby objects are heavily attenuated by the TX and RX
antenna patterns. Therefore, the blocking loss, defined as the
power ratio between the unobstructed to the obstructed
received power, is essentially the diffraction loss around the
blockers. In this sub-section, our mobile-to-mobile human
blocking loss measurements are compared with diffraction loss
predictions found using the Piazzi method described in Section
III.B for human blockers modeled as semi-infinite absorbing
screens of infinite height similar to , .
Fig. 8 shows the time-averaged blocking loss
measurements for different two and three-person blocking
configurations in increasing order of blocking loss. The
predicted blocking losses from the Piazzi method are also
plotted. Depending on the configuration of the blockers, there
can be deep fades in the measurements where the blocking loss
is greater than 30 dB. The blocking loss in all scenarios ranges
from -2.7 dB to 43.5 dB. This range is much larger than those
presented in  and  and further justifies the need to
include human blocking models in 60 GHz channel simulators.
Fig. 8 also shows the errors in the predictions made using the
Piazzi method for the different blocking configurations.
Prediction error is defined as the predicted blocking loss minus
the time-averaged blocking loss. The mean and standard
deviations of the prediction error are -1 dB and 5.2 dB,
respectively. 70% of the configurations had prediction error
between ±5 dB. The majority of configurations with high
blocking loss typically have large positive prediction errors.
High blocking loss may be caused by large diffraction angles.
This suggests that another model, for example, a cylindrical
model, may better predict diffraction around blockers at large
diffraction angles. However, from the standard deviation, we
expect that the absorbing-screen model is sufficient to compute
blocking loss in most applications.
Figure 7. RX antenna received power angular profile relative to
LOS power with incident angle �i = 25 degrees on building.
0 20 40 60 80 100
0 20 40 60 80 100
Figure 8. Comparison of mobile-to-mobile blocking gain
measurements to Piazzi method predictions.
0 1 2 3 4 5 6
Distance from RX [m]
Figure 9. Comparison of access link blocking loss
measurements to UTD predictions.
F. Access Link Human Blocking
The time-averaged blocking loss measurements as a human
blocker walks toward the elevated TX antenna and away from
the RX antenna is plotted in Fig. 8 versus the distance x from
the TX antenna. To predict the blocking loss, the contributions
from transmission through the humans, and scattering and
reflection from nearby objects are again heavily attenuated, so
that the blocking loss is the diffraction loss. Similar to the
mobile-to-mobile case, two rays diffracting around the sides of
the human blocker were considered. Unlike the mobile-to-
mobile case, the absorbing screen modeling the blocker has
finite height, because the antennas are no longer low relative to
the blocker height. The predicted diffraction loss using the
human blocker’s actual width of 0.43 m and an effective height
of 1.61 m for the absorbing screen is also plotted in Fig. 9. This
effective height value was chosen so that mean prediction error
was approximately 0 dB, which corresponded to a standard
deviation of 3.2 dB.
Note that the actual height of the blocker is 1.72 m with a
head height of 0.25 m. From this and other access link blocking
measurements, we found that decreasing the blocker’s head
height by 35% to 45% gave the best prediction.
In this work, 60 GHz measurements of corner diffraction,
scattering from a car, lamppost and building, and human
blocking are presented. The absorbing screen diffraction model
is found to give good comparison with diffraction
measurements. Scattering measurements from cars and
lampposts are found to peak near the specular direction. For
building shadowed mmW links, comparisons of the scattering
measurements with the absorbing screen diffraction model
suggests that the scattering from cars and lampposts is
dominant compared to corner diffraction. This indicates the
need to include scattering models of common urban furniture
in millimeter wave propagation simulators.
The building scattering measurements show that the
majority of received power arrives in the horizontal plane
containing the TX and RX and peaks in the specular direction.
Non-specular contributions were found to originate from
features on the wall, such as ridges and columns. Based on this
result, we suggest utilizing a horizontal plane assumption in
smart beam-finding algorithms when searching for building
scattered paths to decrease complexity and acquisition time.
To account for human blocking in mmW propagation
simulators, several models were previously proposed in the
literature. In this work, we focused on the absorbing screen
model and proposed the use of an effective human height for
the screen height rather than the actual human height.
Validation of this absorbing screen model was performed using
human blocking measurements of single and multiple human
blockers of mobile-to-mobile and access links. Results show
that the absorbing screen model is quite accurate with standard
deviation of prediction error less than 5 dB.
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