Indonesian
Journal
of
Electrical
Engineering
and
Computer
Science
V
ol.
7,
No
.
1,
J
uly
2017,
pp
.
164
169
DOI:
10.11591/ijeecs
.v7.i1.pp164-169
164
Estimation
of
Millimeter
W
a
ve
Atten
uation
Due
to
Rain
Using
2D
Video
Distr
ometer
Data
in
Mala
ysia
Manhal
Alhilali
1
,
Jafri
Din
1*
,
Mic
hael
Sc
h
¨
onhuber
2
,
and
Hong
Yin
Lam
3
1
Wireless
Comm
unication
Centre
,
F
aculty
of
Electr
ical
Engineer
ing,
Univ
ersiti
T
eknolo
gi
Mala
ysia
81310
Johor
Bahr
u,
Johor
,
Mala
ysia
2
Joanneum
Research
Gr
az,
A
ustr
ia
3
Depar
tment
of
Electr
ical
Engineer
ing
T
echnology
,
F
aculty
of
Engineer
ing
T
echnolog
y
,
Univ
ersiti
T
un
Hussein
Onn
Mala
ysia
86400
Batu
P
ahat,
Johor
,
Mala
ysia
1
*Corresponding
author
,
e-mail:
jafr
i@utm.m
y
Abstract
The
increasing
use
of
millimeter
w
a
v
e
frequency
bands
requires
a
good
understanding
of
the
atmo-
spher
ic
channel.
In
equator
ial
regions
,
r
ain
pla
ys
the
centr
al
role
in
the
impair
ment
of
millimeter
w
a
v
e
prop-
agation.
Using
large
amounts
of
precise
data
collected
b
y
a
tw
o-dimensional
video
distrometer
in
Mala
ysia,
the
r
ain-specific
atten
uation
of
both
v
er
tically
and
hor
iz
ontally
polar
iz
ed
w
a
v
es
at
the
38
GHz
frequency
w
as
computed
b
y
applying
the
T
-matr
ix
technique
.
Good
ag
reement
is
obser
v
ed
betw
een
these
computations
and
fit
ted
po
w
er
la
w
models
from
neighbor
ing
areas
,
b
ut
the
ITU-R
Recommendation
P
.838-3
significantly
underestimates
the
r
ain-specific
atten
uation.
The
impor
tance
of
including
r
aindrop
axial
r
atio
in
the
calcula-
tion
is
re
v
ealed
b
y
diff
erences
among
the
local
fitted
coefficients
f
or
the
v
er
tically
polar
iz
ed
estimations
.
The
po
w
er
la
w
fit
is
pro
vided,
and
the
measurement
is
v
er
ified.
K
e
yw
or
ds:
Millimeter
W
a
v
e
,Rain
Atten
uation,
Equator
ial
Regions
,
Raindrop
Siz
e
Distr
ib
uti
on
Cop
yright
c
2017
Institute
of
Ad
v
anced
Engineering
and
Science
.
All
rights
reser
ved.
1.
Intr
oduction
As
the
w
or
ld
increasingly
demands
the
higher
bandwidths
that
millimeter
w
a
v
es
can
pro-
vide
[1],
precise
prediction
and
estimation
of
their
atten
uation
b
y
atmospher
ic
eff
ects
is
cr
ucial
[2].
In
equator
ial
regions
lik
e
Mala
ysia,
hea
vy
precipitation
is
the
dominant
f
actor
that
reduces
link
quality
and
a
v
ailability
[3,
4].
T
o
address
this
issue
,
a
thorough
understanding
of
precipitation
drop
siz
e
distr
ib
ution
(DSD),
shape
,
f
all
v
elocity
and
macro-ph
ysical
st
r
ucture
is
required.
The
DSD
is
par
ticular
ly
impor
tant
,
because
r
aindrops
ar
e
compar
ab
le
in
siz
e
to
w
a
v
elengths
in
the
millimeter
w
a
v
e
r
ange;
it
is
also
kno
wn
that
h
ydrometeors
are
ob
late
spheroids
with
flattened
bases
,
causing
the
r
ain-specific
atten
uation
of
millimeter
w
a
v
es
to
depend
on
their
polar
ization.
Linear
ly
polar
iz
ed
w
a
v
es
are
atten
uated
to
a
g
reater
deg
ree
when
the
polar
izatio
n
is
hor
iz
ontal
r
ather
than
v
er
tical
[5],
and
depolar
ization
of
the
signal
occurs
when
the
polar
ization
is
or
thog-
onal.
A
tw
o-dimensional
video
distrometer
(2D
VD)
can
capture
cross-sections
of
the
drops
[6],
and
theref
ore
allo
ws
accur
ate
measurement
of
these
eff
ects
.
Ho
w
e
v
er
,
that
accur
acy
depends
on
the
a
v
ailability
of
not
only
r
ain
data
b
ut
also
models
that
can
estimate
the
introduced
atten
u-
ation
as
w
ell
as
atten
uation
da
ta
to
v
alidate
these
estimates
.
This
ar
ticle
presents
the
estimated
r
ain-specific
atten
uation
of
linear
ly
polar
iz
ed
millimeter
w
a
v
es
f
or
terrestr
ial
links
,
using
a
y
ear
of
data
collected
b
y
a
f
our
th-gener
ation
2D
VD
installed
at
the
souther
nmost
city
of
peninsular
Mala
ysia
[7].
Data
gathered
b
y
co-located
meteorological
station
and
the
older
38
GHz
link
[8]
are
used
to
v
alidate
the
measurements
.
Receiv
ed
F
ebr
uar
y
19,
2017;
Re
vised
Ma
y
26,
2017;
Accepted
J
une
18,
2017
Evaluation Warning : The document was created with Spire.PDF for Python.
IJEECS
ISSN:
2502-4752
165
2.
Distr
ometer
Measurements
The
2D
VD
uses
tw
o
line-scanning
camer
as
to
capture
contour
images
and
f
all
v
elocities
of
an
y
par
ticles
pass
through
its
10
10
cm
sensing
area,
pro
viding
inf
or
mation
about
shape
,
axial
r
atio
,
and
canting
angle
.
The
relationship
of
r
aindrop
axial
r
atio
to
equiv
alent
diameter
has
been
the
f
ocus
of
man
y
studies
[9,
10,
11,
12].
The
2D
VD
data
computed
from
natur
al
r
aindrops
,
sho
wn
in
red
in
Figure
1,
ag
ree
with
[11]
in
tha
t
the
axial
r
atio
lies
along
the
upper
bound
of
the
Beard-Chung
model
[10]
and
with
[12]
in
that
drops
are
slightly
more
spher
ical.
0
1
2
3
4
5
6
7
8
9
Eq. diameter [mm]
0.4
0.5
0.6
0.7
0.8
0.9
1
Mean axis ratio
Measured Mean Axis Ratio
BC with upper and lower bounds
Figure
1.
Relationship
betw
een
natur
al
r
aindrop
mean
axial
r
atio
and
equiv
alent
diameter
,
com-
pared
with
the
upper
and
lo
w
er
bounds
of
the
Beard-Chung
model
[10].
The
DSD
,
N
(
D
i
)
,
is
the
n
umber
of
drops
per
unit
v
olume
per
unit
drop
diameter
,
which
can
be
calculated
from
the
drop
data
recorded
b
y
the
2D
VD
using
N
(
D
i
)
=
1
t
D
m
k
X
k
=1
1
A
k
v
k
;
(1)
where
t
is
the
integ
r
ation
time
per
io
d
(in
this
case
,
one
min
ute),
m
k
resemb
les
the
n
umber
of
drops
within
th
e
drop
siz
e
inter
v
al
D
,
and
A
k
and
v
k
are
the
eff
ectiv
e
area
and
the
measured
f
all
v
elocity
of
the
drops
,
respectiv
ely
.
While
,
the
r
ainf
all
r
ate
R
in
mm/h
calculated
b
y
dividing
the
r
ain
amount
computed
from
t
he
quotient
of
the
drop’
s
v
olume
and
eff
ectiv
e
area
b
y
the
corresponding
time
inter
v
al
using
R
=
3600
1
t
n
X
i
=1
V
i
A
i
;
(2)
where
n
represents
the
total
n
umber
of
the
visib
le
drops
within
the
per
iod
t
and
V
i
is
the
drop
v
olume
.
3.
Rain-Specific
Atten
uation
Calculation
The
r
ain-specific
atten
uation
depends
on
r
ain
r
ate
,
one-min
ute-integ
r
ated
DSD
,
drops
shape
,
and
w
a
v
elength
and
polar
ization
of
the
oper
ating
frequency
.
The
f
orw
ard
scatter
ing
ampli-
tude
can
be
computed
using
the
T
-matr
ix
method
[13],
assuming
drop
shape
is
an
ob
late
spheroid
with
an
axial
r
atio
as
discussed
in
section
2.,
atten
uation
f
or
hor
iz
ontal
and
v
er
ti
c
a
l
(
H
and
V
)
po-
lar
ization
in
dB/km
can
be
defined
as
H
;V
=
8
:
686
10
3
41
X
i
=1
Im(
f
H
;V
(
D
i
))
N
(
D
i
)
D
i
;
(3)
Estimation
of
mmW
a
v
e
Atten
uation
Due
to
Rain
Using
2D
VD
data
in
Mala
ysia
(Manhal
Alhilali)
Evaluation Warning : The document was created with Spire.PDF for Python.
166
ISSN:
2502-4752
where
is
the
w
a
v
elength
and
f
H
(
D
i
)
and
f
V
(
D
i
)
are
f
orw
ard
scatter
ing
amplitudes
f
or
H
and
V
polar
ization,
respectiv
ely
.
Figure
2
sho
ws
an
e
xample
of
r
ain-specific
atten
uation
time
ser
ies
f
or
the
38
GHz
fre-
quency
from
one
e
v
ent
occurred
on
29
th
of
Apr
il
2016.
At
the
top
of
the
figure
,
one-min
ute
r
ain
in-
tensity
calculated
from
distrometer
data
is
sho
wn
in
mm/h,
f
ollo
w
ed
b
y
the
calculated
r
ain-specific
atten
uation
f
or
H
and
V
polar
ization
at
38
GHz
in
the
middle
of
the
figure
and
finally
the
diff
erence
betw
een
the
tw
o
(
H
V
)
at
the
bottom
of
the
figure
.
06:30
06:45
07:00
07:15
07:30
Apr 29, 2016
0
50
100
150
200
Rainrate[mm/h]
06:30
06:45
07:00
07:15
07:30
Apr 29, 2016
0
20
40
60
Sp. atten. (H-pol) [dB/km]
06:30
06:45
07:00
07:15
07:30
Apr 29, 2016
0
20
40
60
Sp. atten. (V-pol) [dB/km]
06:30
06:45
07:00
07:15
07:30
Time [UTC]
Apr 29, 2016
0
2
4
6
Sp. diff. atten.[dB/km]
(a)
(b)
(c)
(d)
Figure
2.
2D
VD
measurements
of
one
e
v
ent
at
38
GHz;
(a)one-min
ute
r
ainf
all
intensity
,
(b)
r
ain-
specific
atten
uation
f
or
H
P
olar
ization,
(c)
r
ain-specific
atten
uation
f
or
V
polar
ization
and
(d)
dif-
f
erential
r
ain-specific
atten
uation.
Alter
nativ
ely
,
the
r
ain-specific
atten
uation
can
be
appro
ximated
using
a
po
w
er
la
w
rela-
tionship
,
which
uses
coefficients
as
a
function
of
w
a
v
elength
and
polar
ization
to
relate
the
cal-
culated
r
ain-specific
atten
uation
in
dB/km
to
the
calculated
one-min
ute
r
ain
r
ate
in
mm/h,
giv
en
as
H
;V
=
k
H
;V
R
H
;V
;
(4)
where
k
and
are
the
po
w
er
la
w
coefficients
and
R
is
the
r
ain
r
ate
in
mm/h.
The
ITU-R
Rec-
ommendation
P
.838-3
[14]
also
p
ro
vides
a
set
of
k
and
v
alues
f
or
the
frequency
r
ange
from
1
-
1000
GHz.
Ho
w
e
v
er
,
due
to
high
diff
erences
in
the
regional
precipitation
char
acter
istics
,
plenty
of
authors
recommended
diff
erent
local
alter
nativ
es;
within
the
study
region,
locally
der
iv
ed
v
alues
are
presented
f
or
K
uala
Lumpur
[3]
and
Sin
gapore
[15].
F
or
the
one
y
ear
of
2D
VD
measurements
IJEECS
V
ol.
7,
No
.
1,
J
uly
2017
:
164
169
Evaluation Warning : The document was created with Spire.PDF for Python.
IJEECS
ISSN:
2502-4752
167
the
one-min
ute-integ
r
ated
DSD
is
used
to
der
iv
e
the
specific
atten
uation
at
38
GHz
f
or
H
and
V
polar
ization,
and
the
resulted
po
w
er
la
w
fits
presented
in
T
ab
le
1
and
compared
in
Figure
3
with
ITU-R
P
.838-3
and
the
locally
der
iv
ed
coefficients
v
alues
.
T
ab
le
1.
P
o
w
er
la
w
cur
v
e-fitting
coefficients
and
their
goodness
of
fits
f
or
the
relationship
betw
een
r
ain
r
ate
and
r
ain-specific
atten
uation
at
38
GHz
computed
from
2D
VD
data.
P
olar
ization
k
R
2
Hor
iz
ontal
0.400
0.935
0.997
V
er
tical
0.367
0.928
0.987
0
50
100
150
Rainrate [mm/h]
0
10
20
30
40
50
Sp. atten. (H-pol) [dB/km]
2DVD data (38 GHz H)
Singapore (38 GHz H)
Fitted (38 GHz H)
ITU-R P.838-3 (38 GHz H)
Kuala Lumpur (38GHz H)
0
50
100
150
Rainrate [mm/h]
0
10
20
30
40
50
Sp. atten. (V-pol) [dB/km]
2DVD data (38 GHz V)
Singapore (38 GHz V)
Fitted (38 GHz V)
ITU-R P.838-3 (38 GHz V)
Kuala Lumpur (38GHz V)
Figure
3.
Specific
atten
uation
from
2D
VD
in
natur
al
r
ain,
with
der
iv
ed
po
w
er
la
w
fit,
compared
with
other
fits
from
the
ITU-R
Recommendation
P
.838-3
[14]
K
uala
Lumpur
data
[3]
and
Singapore
data
[15].
In
gener
al,
the
ITU-R
Recommendation
P
.838-3
r
ain-specific
atten
uation
v
alues
unac-
ceptab
ly
lo
w
compared
with
those
from
the
2D
VD
data,
while
a
closer
ag
reement
w
as
achie
v
ed
b
y
using
the
locally
der
iv
ed
coefficients
.
The
significant
diff
erences
can
be
accounted
f
or
b
y
the
use
of
theoretical
DSDs
f
or
diff
erent
regions
in
the
ITU-R
Recommendation
P
.838-3,
whereas
the
locally
der
iv
ed
v
alues
are
based
on
actual
DSDs
fitting
using
one-min
ute-integ
r
ated
data.
Fur-
ther
more
,
the
drop
axial
r
atio
significant
necessity
in
deter
mining
the
r
ain-specific
atten
uation
f
or
H
and
V
polar
ization,
leads
to
noticeab
le
diff
erences
in
V
polar
ization
v
alues
calculated
from
the
2D
VD
data
compared
with
other
locally
der
iv
ed
v
alues
.
Additionally
,
there
is
a
diff
erence
betw
een
the
K
uala
Lumpur
and
Singapore
v
alues
,
the
latter
of
which
are
in
line
with
the
2D
VD
hor
iz
ontal
v
alues;
w
e
attr
ib
ute
this
to
the
closer
pro
ximity
of
the
2D
VD
to
Singapore
than
K
uala
Lumpur
.
Estimation
of
mmW
a
v
e
Atten
uation
Due
to
Rain
Using
2D
VD
data
in
Mala
ysia
(Manhal
Alhilali)
Evaluation Warning : The document was created with Spire.PDF for Python.
168
ISSN:
2502-4752
4.
Comparison
of
Atten
uation
Measurements
The
data
sho
w
that
the
ITU-R
Recommendation
P
.838-3
underestimates
the
r
ain-specific
atten
uation
b
y
6-25%.
T
ab
le
2
compares
the
r
ain-specific
atten
uation
v
alues
estimated
f
or
se-
lected
r
ain
r
ates
using
the
fitted
coefficients
from
2D
VD
data
with
those
from
the
ITU-R
Recom-
mendation
P
.838-3
v
alues
.
T
ab
le
2.
Compar
ison
of
t
he
2D
VD
and
ITU-R
Recommendation
P
.838-3
estimations
of
r
ain-
specific
atten
uation
dB/km
at
38
GHz
f
or
H
and
V
polar
ization,
presented
according
to
r
ain
r
ate
mm/h.
Rain
r
ate
(mm/h)
P838-3,
H
2D
VD
,
H
P838-3,
V
2D
VD
,
V
1
0.400
0.400
0.384
0.387
5
1.654
1.801
1.522
1.634
10
3.0483
3.444
2.754
3.110
25
6.840
8.112
6.030
7.277
50
12.605
15.510
10.908
13.846
100
23.231
29.65
3
19.733
26.343
T
o
f
ur
ther
quantify
the
2D
VD
r
ain-specific
atten
uation
results
and
e
xamine
the
long-ter
m
eff
ect
of
r
ain
on
terrestr
ial
links
,
a
compar
ison
of
its
complementar
y
cum
ulativ
e
distr
ib
ution
func-
tion
(CCDF)
with
the
fitting,
as
w
ell
as
that
of
the
ITU-R
Recommendation
P
.838-3,
is
presented
in
Figure
4.
0
10
20
30
40
50
[dB/km]
10
-2
10
-1
10
0
Time Percentage [%]
Fitted
2DVD DSD
ITU-R 838-3
Singapore Fitting
Figure
4.
Compar
ison
of
r
ain-specific
atten
uation
CCDFs
of
H
P
olar
ization
at
38
GHz.
5.
Conc
lusion
This
ar
ticle
repor
ts
data
gathered
b
y
a
2D
video
distro
meter
in
Mala
ysia
f
or
the
first
time
.
The
r
ain-specific
atten
uation
of
hor
iz
ontally
and
v
er
tically
polar
iz
ed
millimeter
w
a
v
es
has
been
computed
from
actual
r
ain
data
using
T
-matr
ix
calculations
.
The
fitted
po
w
er
la
w
has
been
com-
pared
with
other
fits
from
neighbor
ing
areas
and
the
ITU-R
Recommendation
P
.838-3.
While
the
T
-matr
ix
calculations
fitted
po
w
er
la
w
are
in
good
ag
reement
with
the
local
fitted
la
ws
,
there
is
significantly
lo
w
er
ag
reement
with
the
ITU-R
recommendation,
which
might
be
due
to
the
high
v
ar
iability
of
DSD
in
equator
ial
regions
.
This
under
lines
the
impor
tance
of
local
po
w
er
la
w
coeffi-
cients
f
or
the
estimation
of
r
ain-specific
atten
uation.
The
r
aindrop
axial
r
atio
is
also
impor
tant;
the
discrepancies
appeared
in
other
fits
of
the
v
er
tically
polar
iz
ed
data
due
to
the
use
of
older
equip-
ment
and
modeled
axial
r
at
ios
which
do
not
represent
the
actual
shape
of
r
aindrops
.
The
local
estimations
can
theref
ore
pro
vide
b
etter
predictions
as
the
w
or
ld
mo
v
es
to
w
ards
higher-frequency
demands
.
IJEECS
V
ol.
7,
No
.
1,
J
uly
2017
:
164
169
Evaluation Warning : The document was created with Spire.PDF for Python.
IJEECS
ISSN:
2502-4752
169
Ac
kno
wledg
ement
This
w
or
k
has
been
funded
b
y
Ministr
y
of
Education
Mala
ysia
and
Univ
ersiti
T
eknologi
Mala
ysia
under
HICOE
Univ
ersity
Gr
ant
V
ot.
No
.
4J221
and
par
tially
de
v
eloped
in
the
fr
ame
w
or
k
of
the
ESA/ESTEC/Contr
act
4000106180/12/NL/NR.
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Evaluation Warning : The document was created with Spire.PDF for Python.