Indonesian
J
our
nal
of
Electrical
Engineering
and
Computer
Science
V
ol.
25,
No.
1,
January
2022,
pp.
358
∼
364
ISSN:
2502-4752,
DOI:
10.11591/ijeecs.v25.i1.pp358-364
❒
358
Recongurable
intelligent
surfaces
assisted
wir
eless
communication
netw
orks:
er
godic
capacity
and
symbol
err
or
rate
Dinh-Thuan
Do,
Chi-Bao
Le
F
aculty
of
Electronics
T
echnology
,
Industrial
Uni
v
ersity
of
Ho
Chi
Minh
City
,
Ho
Chi
Minh
City
,
V
ietnam
Article
Inf
o
Article
history:
Recei
v
ed
Apr
19,
2021
Re
vised
No
v
15,
2021
Accepted
No
v
25,
2021
K
eyw
ords:
Er
godic
capacity
Recongurable
intelligent
surf
aces
Symbol
error
rate
ABSTRA
CT
By
enabling
recongurable
intelligent
surf
aces
(RIS),
we
can
deplo
y
intelligent
re-
ecting
signals
from
the
base
station
to
des
tinations.
Dif
ferent
from
traditional
relay-
ing
system,
RIS
relies
on
programmable
metasurf
aces
and
mirrors
to
impro
v
e
system
performance
of
destinations.
W
e
deri
v
e
the
form
ulas
of
main
system
performance
metrics
suc
h
as
er
godic
capacity
and
symbol
error
rate
(SER).
Based
on
types
of
mod-
ulation,
we
need
to
demonstrate
other
parameters
which
mak
e
inuence
to
system
per
-
formance.
W
e
sho
w
analytically
that
the
number
of
reecting
elem
ents
along
with
the
transmit
po
wer
at
the
source
can
impro
v
e
system
performance.
Moreo
v
er
,
we
check
the
e
xactness
of
deri
v
ed
e
xpressions
by
matching
Monte-Carlo
with
analyti
cal
simu-
lations.
Finally
,
we
nd
the
best
performance
can
be
achie
v
ed
at
specic
parameters
and
results
are
v
eried
by
e
xplicit
simulations.
This
is
an
open
access
article
under
the
CC
BY
-SA
license
.
Corresponding
A
uthor:
Dinh-Thuan
Do
F
aculty
of
Electronics
T
echnology
,
Industrial
Uni
v
ersity
of
Ho
Chi
Minh
City
12
Nguyen
V
an
Bao
Street,
Go
V
ap
District,
Ho
Chi
Minh
City
700000,
V
ietnam
Email:
dodinhthuan@iuh.edu.vn
1.
INTR
ODUCTION
T
o
implement
ne
xt-generation
wireless
communications,
one
can
deplo
y
recongurable
int
elligent
surf
aces
(RISs)
to
enable
current
systems
with
solid
requirements
such
as
lo
w
cost,
high
ener
gy-ef
cienc
y
and
higher
bandwidth
ef
cienc
y
.
RISs
e
xhibit
their
appealing
ability
by
adjusting
the
propag
ation
of
the
electro-
magnetic
w
a
v
es
[1]–[3].
By
inte
grating
of
passi
v
e
and
reecting
units,
the
RIS-aided
systems
can
adjust
phases
and
amplitudes
independently
for
the
incident
signals.
Further
,
RIS
pro
vides
a
massi
v
e
connections
and
e
x-
ploits
a
full-duple
x
scheme
to
reect
signals
to
destinations.
As
main
adv
ances,
the
RIS
sho
ws
benets
when
we
compare
it
with
the
contemporary
relaying
systems.
First,
to
a
v
oid
po
wer
-hungry
radio
frequenc
y
process-
ing,
the
RIS
is
deplo
yed
as
a
passi
v
e
de
vice
and
thus
less
ener
gy
is
acquired
to
conduct
the
reection.
Second,
to
introduce
lo
w-cost
deplo
yment,
the
RIS
can
be
easily
deplo
yed
on
v
arious
en
vironmental
objects,
for
e
x-
ample
b
uilding
f
acades,
street
signs
and
adv
ertisement
boards
[4].
Furthermore,
in
percepti
v
e
of
information
transfer
,
the
reection
pattern
is
implemented
at
the
RIS
to
impro
v
e
system
performance
[5]–[7].
Specically
,
Rehman
et
al.
[8]
studied
e
xpressions
of
the
outage
probability
and
a
v
erage
sum-rate
by
assuming
that
the
RIS-aided
system
is
optimized
when
the
system
can
achie
v
e
the
highest
instantaneous
end-to-end
signal-to-noise
ratio
(SNR).
RIS
thus
is
deplo
yed
to
impro
v
e
the
current
systems
in
terms
of
in-
terference
cancellation,
s
ecure
transmission,
wireless
co
v
erage,
throughput
enhancement
,
wireless
information
and
po
wer
transfer
.
Importantly
,
P
an
et
al.
[9]
proposed
the
system
to
allo
w
the
angle
of
reection
of
each
RIS
J
ournal
homepage:
http://ijeecs.iaescor
e
.com
Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian
J
Elec
Eng
&
Comp
Sci
ISSN:
2502-4752
❒
359
element
can
be
adjusted
to
enhance
the
co
v
erage
performance
signicantly
.
While
the
amplify-and-forw
ard
(AF)
sho
ws
high
comple
xity
in
signal
processing,
and
w
orks
in
full-duple
x
with
de
graded
performance
due
to
self-interference,
RIS
only
reects
the
recei
v
ed
signals
passi
v
ely
which
is
prominent
compared
to
the
con-
v
entional
relaying
systems.
As
a
result,
RIS-aided
systems
enhance
the
system
ener
gy
ef
cienc
y
(EE)
with
high
spectral
ef
cienc
y
(SE)
without
additional
transmission
po
wer
consumption.
By
combining
both
non-
orthogonal
multiple
access
(NOMA)
[10]–[14]
and
RIS,
the
NOMA-RIS
is
proposed
to
impro
v
e
the
system
performance
in
specic
system
metrics.
Research
e
xplored
RIS
system
by
combining
the
phas
e
shifts
at
the
RIS
and
the
joint
optimization
of
the
beamformer
at
the
base
station,
then
system
performance
can
be
optimized
[15],
[16].
In
[17]–[21],
v
arious
system
models
are
presented
to
demonstrate
benets
of
RIS.
F
or
e
xample,
in
[17],
Jiang
and
Shi
considered
the
assistance
of
a
multi-element
RIS
to
boost
the
performance
of
o
v
er
-the-air
computation.
Research
presented
secure
transmission
in
the
presence
of
ea
v
esdroppers
[18]–[20].
The
y
considered
the
system
that
multi-antenna
base
station
serv
ers
multiple
single-antenna
le
gitimate
users
with
the
assistance
of
a
multi-element
RIS.
Y
an
et
al.
[21]
proposed
that
a
multi-element
RIS
is
required
to
assist
the
primary
communication
between
a
multi-antenna
base
station
and
a
single-antenna
user
.
Moti
v
ated
by
recent
studies
[18]–[21],
this
article
aims
to
consider
tw
o
main
system
metrics,
i.e.
er
godic
capacity
and
symbol
error
rate
for
point-to-point
RIS-aided
system.
The
main
notations
of
this
paper
is
sho
wn
as
follo
ws:
E
[
•
]
denotes
e
xpectation
operation;
f
X
(
•
)
and
F
X
(
•
)
denote
the
probability
density
function
(PDF)
and
the
cumulati
v
e
distrib
ution
function
(CDF)
of
a
random
v
ariable
X
;
G
m,n
p,q
(
•
|•
)
denotes
the
Meijer
-G
function
of
a
single
v
ariable;
Γ
(
•
)
is
the
Gamma
function;
γ
(
•
,
•
)
is
the
lo
wer
incomplete
Gamma
function;
Q
(
•
)
is
the
Gaussian
error
function.
2.
SYSTEM
MODEL
W
e
consider
the
do
wnlink
from
the
base
station
(BS)
which
is
required
to
serv
e
a
destination
(D)
with
the
help
of
RIS,
sho
wn
in
Figure
1.
In
particular
,
the
point-to-point
RIS-assisted
wireless
s
ystem
in
this
scenario
is
studied
with
single-antenna
design
for
BS
and
D
nodes,
while
K
metasurf
aces
is
required
at
RIS.
W
e
represent
the
baseband
equi
v
alent
f
ading
channels
between
t
he
BS
and
the
k
th
metasurf
ace
of
the
RIS,
¯
h
k
.
In
the
second
hop,
the
channel
between
the
k
th
metasurf
ace
and
node
D
is
denoted
as
¯
g
k
.
W
e
assume
characteristic
of
channels
such
as
independent,
identical
and
slo
wing
v
arying.
D
B
S
B
l
o
c
k
i
n
g
o
b
j
e
c
t
s
R
I
S
R
e
f
l
e
c
t
e
d
L
i
n
k
R
e
f
l
e
c
t
e
d
L
i
n
k
k
h
k
g
Figure
1.
The
point-to-point
RIS-assisted
system
W
e
denote
P
S
ass
the
normalized
transmission
po
wers
at
the
BS.
The
recei
v
ed
signal
at
user
D
is
gi
v
en
by:
¯
y
=
p
P
S
K
X
k
=1
¯
h
k
¯
g
k
v
k
¯
x
+
ω
,
(1)
where
the
metasurf
ace
has
v
k
=
|
v
k
|
exp
j
¯
θ
k
,
¯
θ
k
stands
for
the
phase
shift
related
to
k
th
reecti
v
e
units
in
the
RIS
and
ω
represents
the
additi
v
e
white
Gaussian
noise
(A
WGN)
and
such
a
noise
is
considered
as
a
zero-mean
comple
x
Gaussian
(ZMCG)
process
with
v
ariance
equal
N
0
.
In
this
case,
unit
po
wer
is
assumed
for
signal
x
,
i.e,
E
n
|
x
|
2
o
=
1
.
Recongur
able
intellig
ent
surfaces
assisted
wir
eless
communication
networks
...
(Dinh-Thuan
Do)
Evaluation Warning : The document was created with Spire.PDF for Python.
360
❒
ISSN:
2502-4752
In
our
study
,
we
assume
|
v
k
|
=
1
which
is
in
line
with
real
deplo
yment
[22].
It
is
assumed
that
the
RIS
has
perfect
kno
wledge
of
the
phase
of
¯
h
k
,
¯
θ
¯
h
k
and
the
one
¯
g
k
,
¯
θ
¯
g
k
,
and
selects
the
optimal
phase
shifting,
i.e.
¯
θ
k
=
−
¯
θ
¯
h
k
+
¯
θ
¯
g
k
.
(2)
T
o
easier
manipulations,
we
denote
A
=
K
P
k
=1
¯
h
k
|
¯
g
k
|
as
baseband
equi
v
alent
channel
coef
cient.
Then,
we
can
compute
the
recei
v
ed
signal
as
(3).
¯
y
=
A
x
+
ω
.
(3)
T
o
further
achie
v
e
other
system
metrics,
we
need
to
obtain
the
instantaneous
the
signal-to-noi
se-ratio
(SNR)
as
(4).
.
¯
γ
=
|A|
2
P
S
N
0
,
(4)
W
e
can
re
write
(4)
as:
¯
γ
=
|A|
2
ρ
S
,
(5)
in
which
ρ
S
=
P
S
/
N
0
represents
for
the
BS
in
term
of
signal-to-noise
radio
(SNR).
It
is
better
e
xamine
important
system
performance
at
destination
and
the
other
system
performance
metrics
can
be
determined
by
e
xploiting
such
SNR.
W
e
e
xpect
that
high
SNR
leads
to
better
system
performance.
3.
AN
AL
YSIS
OF
ERGODIC
CAP
A
CITY
Since
er
godic
capacity
plays
an
important
role
to
e
v
aluate
system
performance,
we
deri
v
e
a
closed-
form
e
xpression
for
the
er
godic
capacity
(EC)
as
(6).
¯
C
=
E
[log
(1
+
¯
γ
)]
=
∞
Z
0
ln
(1
+
x
)
f
¯
γ
(
x
)
dx.
(6)
In
this
step,
ln
(1
+
x
)
can
be
formulated
with
the
help
of
[23,
Eq.
(8.4.6.5)]:
ln
(1
+
x
)
=
G
1
,
2
2
,
2
x
1
,
1
1
,
0
,
(7)
where
G
m,n
p,q
(
•
|•
)
denotes
the
Meijer
-G
function
of
a
single
v
ariable.
So,
we
can
e
xpress
the
PDF
and
CDF
of
¯
γ
dene
in
(6)
as
[24,
Eq.
(24)],
[24,
Eq.
(25)]:
f
¯
γ
(
x
)
=
x
(
a
−
1)/2
2
b
a
+1
Γ
(
a
+
1)
ρ
(
a
+1)/2
S
exp
−
1
b
r
x
ρ
S
,
(8)
and
F
¯
γ
(
x
)
=
1
Γ
(
a
+
1)
γ
a
+
1
,
1
b
r
x
ρ
S
,
(9)
where
a
=
K
π
2
(16
−
π
2
)
−
1
and
b
=
8
π
−
π
2
,
Γ
(
•
)
is
the
Gamma
function
and
γ
(
•
,
•
)
is
the
lo
wer
incomplete
Gamma
function.
W
ith
the
aid
of
[25,
Eq.
(8.350.1)],
(9)
can
be
claimed
by
(10).
F
¯
γ
(
x
)
=
1
Γ
(
a
+
1)
∞
X
l
=0
(
−
1)
l
x
(
a
+
l
+1)/2
l
!
(
a
+
l
+
1)
ρ
(
a
+
l
+1)/2
S
b
a
+
l
+1
.
(10)
Then,
substituting
(8)
and
(7)
into
(6),
the
er
godic
capacity
can
be
e
xpressed
as
(11).
Indonesian
J
Elec
Eng
&
Comp
Sci,
V
ol.
25,
No.
1,
January
2022:
358–364
Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian
J
Elec
Eng
&
Comp
Sci
ISSN:
2502-4752
❒
361
¯
C
=
∞
Z
0
G
1
,
2
2
,
2
x
1
,
1
1
,
0
f
¯
γ
(
x
)
dx
=
1
2
b
a
+1
Γ
(
a
+
1)
ρ
(
a
+1)/2
S
∞
Z
0
x
(
a
−
1)/2
G
1
,
2
2
,
2
x
1
,
1
1
,
0
exp
−
1
b
r
x
ρ
S
dx
(11)
Let
t
=
√
x
→
t
2
=
x
→
2
tdt
=
dx
and
by
applying
the
[26,
Eq.
(3.3.12)],
the
closed-form
solution
of
¯
C
for
the
er
godic
capacity
can
be
determined
as
(12).
¯
C
=
1
b
a
+1
Γ
(
a
+
1)
ρ
(
a
+1)/2
S
∞
Z
0
t
(
a
+1)
−
1
exp
−
t
b
√
ρ
S
G
1
,
2
2
,
2
t
2
1
1
,
1
1
,
0
dt
=
2
a
√
π
Γ
(
a
+
1)
G
1
,
4
4
,
2
4
b
2
ρ
S
−
a
/2
,
(1
−
a
)/2
,
1
,
1
1
,
0
.
(12)
4.
SYMBOL
ERR
OR
RA
TE
Let
denote
α
and
β
as
constants.
In
particular
,
the
modulation
types
depend
on
v
alues
of
α
and
β
.
W
e
treat
the
binary
phase-shift
k
e
ying
(BPSK)
modulation
corresponding
to
α
=
1
,
β
=
2
.
If
v
alues
are
α
=
2
,
β
=
1
,
the
y
represent
for
quadrature
phase
shift
k
e
ying
(QPSK)
and
4-quadrature
amplitude
modulation
(4-
QAM)
in
[27],
Q
(
•
)
is
the
Gaussian
error
function.
F
or
the
RIS-aided
point-to-point
system,
t
he
Symbol
Error
Rate
(SER)
need
be
computed
as
[27]:
S
=
α
E
n
Q
p
β
¯
γ
o
=
a
2
π
∞
Z
0
F
¯
γ
x
2
b
e
−
x
2
2
dx
t
∆
=
x
2
/
b
=
α
√
β
2
√
2
π
∞
Z
0
e
−
β
2
x
√
x
F
¯
γ
(
t
)
dt.
(13)
substituting
(10)
into
(9),
the
SER
of
RIS-aided
system
can
be
e
xpressed
as
(14).
S
=
α
√
β
2
√
2
π
∞
Z
0
e
−
β
2
x
√
x
F
¯
γ
(
t
)
dt
=
∞
X
l
=0
α
√
β
(
−
1)
l
l
!2
√
2
π
Γ
(
a
+
1)
(
a
+
l
+
1)
ρ
(
a
+
l
+1)/2
S
b
a
+
l
+1
∞
Z
0
e
−
β
2
x
x
(
a
+
l
)/2
dt.
(14)
W
e
then
use
the
result
from
[25,
Eq.
(3.351.3)],
the
closed-form
e
xpression
can
be
obtained
to
indicate
the
SER
performance.
In
particular
,
the
e
xpression
of
S
can
be
achie
v
ed
as
(15).
S
=
∞
X
l
=0
α
(
−
1)
l
2
(
a
+
l
)/2
β
(
−
a
−
l
)/2
Γ
((
a
+
l
+
1)/2)
l
!
√
2
π
Γ
(
a
+
1)
(
a
+
l
+
1)
ρ
(
a
+
l
+1)/2
S
b
a
+
l
+1
.
(15)
Remark:
As
our
observ
ation,
(15)
depends
on
v
alues
of
both
α
and
β
.
Therefore,
by
adjusting
the
modulation
type,
we
can
obtain
dif
ferent
performance.
W
e
e
xpect
to
compare
the
SER
performance
by
comparing
tw
o
types,
i.e.
BPSK
and
QPSK.
Further
,
the
SNR
at
the
BS
plays
k
e
y
role
to
indicate
impro
v
ement
of
SER
since
(15)
also
contains
ρ
s
.
Recongur
able
intellig
ent
surfaces
assisted
wir
eless
communication
networks
...
(Dinh-Thuan
Do)
Evaluation Warning : The document was created with Spire.PDF for Python.
362
❒
ISSN:
2502-4752
5.
NUMERICAL
RESUL
TS
This
section
is
conduced
to
v
erify
e
xpressions
obtained
in
the
pre
vious
sections.
Monte
Carlo
simu-
lations
are
conducted
to
e
xamine
e
xactness
of
mathematical
e
xpressions
of
performance
analysis.
W
e
focus
on
the
RIS-assisted
wireless
system
by
e
xamining
these
metrics
such
as
er
godic
capacity
and
SER.
Monte-Carlo
results
are
performed
by
run
of
10
7
independent
channel
realizations.
Figure
2
sho
ws
the
er
godic
capacity
performance
when
we
change
the
number
of
metasurf
aces
K
.
As
our
observ
at
ion,
K
=
100
sho
ws
the
corresponding
er
godic
capacity
as
the
highest
case
among
v
e
cases.
It
can
be
seen
that
the
analytical
results
are
matched
well
with
Monte
Carlo
simulations
in
the
whole
range
of
SNR.
W
e
also
observ
e
that
the
er
godic
capacity
increases
by
increasing
SNR
at
the
BS
ρ
s
.
This
is
because
the
end-to-end
SNR
depends
on
SNR
at
the
BS,
then
the
corresponding
er
godic
capacity
can
be
impro
v
ed
at
high
SNR
ρ
s
re
gion.
The
performance
g
aps
among
v
e
cases
are
the
same
in
whole
range
of
ρ
s
.
In
Figure
3,
the
er
godic
capacity
can
be
enhanced
at
higher
num
ber
of
metasurf
aces
K
of
the
RIS.
It
can
be
seen
clearly
the
er
godic
capacity
only
increase
v
ery
f
ast
when
K
changes
from
0
to
400.
After
this
point,
the
er
godic
capacity
just
increase
slightly
.
The
er
godic
capacity
performance
of
RIS-assisted
s
ystem
for
the
destination
is
compared
with
set
of
SNR
at
the
BS,
i.e.
ρ
s
=
20
,
30
,
40
,
50
.
W
e
observ
e
that
with
the
increase
of
ρ
s
and
K
,
the
er
godic
capacity
performance
of
the
considered
system
is
impro
v
ed
signicantly
at
lo
w
re
gion
of
SNR.
Therefore,
the
design
of
man
y
metasurf
aces
K
is
unnecessary
.
-20
-10
0
10
20
30
40
50
0
5
10
15
20
25
K = 100, 70, 40, 20, 10, 5
Figure
2.
Increasing
SNR
to
look
at
curv
es
of
er
godic
capacity
0
200
400
600
800
1000
12
14
16
18
20
22
24
26
28
S
= 20, 30, 40, 50 (dB)
Figure
3.
The
number
of
meta-surf
ace
mak
es
inuence
to
er
godic
capacity
Indonesian
J
Elec
Eng
&
Comp
Sci,
V
ol.
25,
No.
1,
January
2022:
358–364
Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian
J
Elec
Eng
&
Comp
Sci
ISSN:
2502-4752
❒
363
Figure
4
demonstrates
SER
performance
for
the
case
of
BPSK
modulation
when
we
v
ary
the
SNR
at
the
BS
ρ
s
from
-40
dB
to
10
dB.
It
can
be
seen
clearly
that
SER
can
be
impro
v
ed
signicantly
at
the
range
of
ρ
s
from
-40
dB
to
-10
dB.
The
main
reason
is
that
the
(15)
depends
on
ρ
s
.
Moreo
v
er
,
the
best
SER
performance
can
be
reported
as
K
=
20
.
W
e
can
conclude
that
by
designing
more
metasurf
aces
K
at
the
RIS,
we
can
achie
v
e
good
performance
in
term
of
SER.
Similarly
,
Figure
5
sho
ws
similar
performance
for
the
case
of
QPSK
modulation.
-40
-30
-20
-10
0
10
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
K = 5, 10, 15, 20
Figure
4.
SER
v
ersus
the
SNR
at
the
BS
usi
ng
BPSK
-40
-30
-20
-10
0
10
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
K = 20, 15, 10, 5
Figure
5.
SER
v
ersus
the
SNR
at
the
BS
using
QPSK
6.
CONCLUSION
W
e
considered
the
wireless
system
by
enabling
RIS
at
the
do
wnlink.
W
e
e
xamine
the
system
per
-
formance
at
tw
o
main
system
metrics,
i.e.
er
godic
capacity
and
SER.
W
e
deri
v
ed
cl
o
s
ed-form
e
xpressions
of
er
godic
capacity
and
SER.
Based
on
these
deri
v
ations,
we
nd
that
reecting
coef
cient
K
of
the
RIS
that
maximizes
the
the
system
performance
at
reasonable
v
alue
of
transmit
SNR
at
the
base
station.
Simulations
sho
wed
that
the
main
parameters
such
as
transmit
SNR
at
the
base
station
is
found
as
main
controlling
param-
eters
compared
with
the
number
of
metasurf
aces.
The
numerical
results
indicate
that
the
er
godic
capacity
still
has
limitations
although
we
increase
the
number
of
metasurf
aces
at
RIS.
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Mathematics,
v
ol.
348,
1st
ed.
Berlin,
German
y:
Springer
-V
erlang,
1973,
doi:
10.1007/BFb0060468.
[27]
A.
J.
Goldsmith,
W
ir
eless
Communications
.
Cambridge,
UK:
Cambridge
Uni
v
ersity
Press,
2005.
BIOGRAPHIES
OF
A
UTHORS
Dinh-Thuan
Do
(Senior
Member
,
IEEE)
recei
v
ed
the
B.S.,
M.Eng.,
and
Ph.D.
de
grees
in
communic
ations
engineering
from
V
ietnam
National
Uni
v
ersity
(VNU-HCM),
in
2003,
2007,
and
2013,
respecti
v
ely
.
His
research
interests
include
signal
processing
in
wireless
communications
net-
w
orks,
cooperati
v
e
com
munications,
nonorthogonal
multiple
access,
full-duple
x
transmission,
and
ener
gy
harv
es
ting.
He
w
as
a
recipient
of
the
Golden
Globe
A
w
ard
from
the
V
ietnam
Ministry
of
Science
and
T
echnology
,
in
2015
(T
op
ten
e
xcellent
young
scientists
nationwide).
He
has
serv
ed
as
a
guest
editor
for
eight
prominent
SCIE
journals.
He
is
currently
serving
as
an
associate
editor
for
six
journals,
including
EURASIP
Journal
on
W
ireless
Communications
and
Netw
orking,
Computer
Communications
(Else
vier),
and
KSII
T
ransactions
on
Internet
and
Information
Syst
ems.
He
can
be
contacted
at
email:
dodinhthuan@iuh.edu.vn.
Chi-Bao
Le
w
as
born
in
Binh
Thuan,
V
ietnam.
He
is
currently
pursuing
the
master’
s
de
gree
in
wireless
communications.
He
has
w
ork
ed
closely
with
Dr
.
Thuan
at
the
W
ireless
Commu-
nications
and
Signal
Processing
Research
Group,
Industrial
Uni
v
ersity
of
Ho
Chi
Minh
City
,
V
iet-
nam.
His
research
interests
include
electronic
design,
signal
processing
in
wireless
communications
netw
orks,
non-orthogonal
multiple
access,
and
ph
ysical
layer
security
.
He
can
be
contacted
at
email:
lechibao@iuh.edu.vn.
Indonesian
J
Elec
Eng
&
Comp
Sci,
V
ol.
25,
No.
1,
January
2022:
358–364
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