Internati
o
nal
Journal of Ele
c
trical
and Computer
Engineering
(IJE
CE)
Vol
.
5
,
No
. 3,
J
une
2
0
1
5
,
pp
. 53
9~
54
7
I
S
SN
: 208
8-8
7
0
8
5
39
Jo
urn
a
l
h
o
me
pa
ge
: h
ttp
://iaesjo
u
r
na
l.com/
o
n
lin
e/ind
e
x.ph
p
/
IJECE
Alleviating Interference th
rough Cognitive Radio for LTE-
Advan
ced Network
Tsung-Hui
Chuang*,
Gu
an
-H
on
g Chen
*,
Men
g
-Hsu
n
Tsai*,
Chun
-Lung Lin
*
*
*Departm
ent
of
Com
puter Scien
ceand
Inform
ati
on E
ngin
eering
,
Nationa
l Cheng
Kung Universit
y
, T
a
iwan
** Industrial
Technolog
y
R
e
sear
ch Institute (ITR
I), Taiwan
Article Info
A
B
STRAC
T
Article histo
r
y:
Received
Ja
n 14, 2015
Rev
i
sed
Ap
r
18
, 20
15
Accepte
d
May 2, 2015
In the LTE-Ad
vanced ne
twork, som
e
fem
t
ocells are deplo
y
e
d
within a
macroecell for
improving through put of
indo
or user equipments (UEs),
which are referr
ed to as fem
t
ocell UEs (FUEs).
Cross-tier interf
erenc
e
is an
im
portant issue in this deplo
y
m
e
nt
, which may significan
tly
impact signal
qualit
y
be
tween
M
acroc
ell
Ba
s
e
S
t
ations
(M
BS
s
)
and M
acr
ocel
l Us
er
Equipm
ents
(M
UEs
)
, es
pecia
l
l
y
for MUEs
near
the fem
t
oce
ll. T
o
reliev
e
this
problem, the
Third Generation
Partne
rship Project Long Ter
m
Evolution-
Advanced (3GP
P LTE-Advan
c
ed) def
i
ned
the
cognit
i
ve
radi
o enhan
ced
femtocell to
coo
r
dinate interfer
e
nce
for
LTE-Advanced
Network
.
Cognitive
radio femtocells
have the
ability to
sense radio
environment to
obtain rad
i
o
parameters
. In
this pap
e
r, we inve
s
t
i
g
at
ed th
e perform
an
ce
of exis
t
i
ng
schemes based
on fraction
a
l
frequency
reuse. Th
erefor
e, w
e
proposed
aschem
e with
cognitive radio
t
echnolog
y
to i
m
p
rove the per
f
orm
a
nce of
fractional fre-q
uency
r
e
use scheme. Si
mulation results showed that our
scheme can ef
fectiv
ely
enhan
c
e aver
age downlink throughput o
f
FUEs as
well
as th
e to
tal
downlink throug
hput in
LTE-Ad
vanced
Network
s
.
Keyword:
Co
gn
itiv
e rad
i
o
Femto
cell
Fract
i
o
nal
f
r
eq
uency
re
use
In
ter-cell in
terferen
c
e
co
ord
i
n
a
tion
LTE-Adva
nce
d
networks
Copyright ©
201
5 Institut
e
o
f
Ad
vanced
Engin
eer
ing and S
c
i
e
nce.
All rights re
se
rve
d
.
Co
rresp
ond
i
ng
Autho
r
:
Tsun
g-
Hu
i C
h
u
a
ng
,
Depa
rt
m
e
nt
of
C
o
m
put
er Sci
e
nce a
n
d
I
n
f
o
rm
at
i
on E
n
gi
nee
r
i
n
g
,
Natio
n
a
l
C
h
eng
Kung
Un
i
v
ersity,
No1
,
Un
iv
ersity Ro
ad, Tainan City, Taiwan,
ROC.
Em
a
il: h
u
e
i@im
s
l
ab
.csie.n
c
ku
.ed
u
.tw
1.
INTRODUCTION
In orde
r t
o
acc
omm
odate the
rapi
d
growt
h
of
wireless tra
f
fic, it is essenti
a
l to im
prove
t
h
ecapacity
o
f
cu
rren
t
cellu
lar n
e
two
r
k
s
for
pro
v
i
d
i
ng
h
i
gh
er d
a
ta rat
e
s and
b
e
tter
q
u
a
lityo
f
serv
ice (Qo
S
). Thus, th
e
fo
urt
h
ge
nerat
i
on
(4
G) m
obl
i
e
net
w
o
r
k
us
e a prom
i
s
i
ng
m
odul
at
i
o
n t
echn
o
l
o
gy
, i
t
sai
d
t
h
at
Ort
h
og
o
n
al
Freq
u
e
n
c
y
Div
i
sion
Mu
ltip
l
e
x
(OFDM
)
.
Th
e
4G m
o
b
ile co
mm
u
n
i
catio
n
system
s, in
clu
d
i
n
g
th
e
Th
ird
Gene
rat
i
o
n Pa
rt
ner
s
hi
p P
r
o
j
ect
Lon
g
Ter
m
Evol
ut
i
o
n
-
Ad
va
nced
(
3
GPP
LTE
-A
d
v
ance
d
)
[
2
]
a
n
d
IEE
E
8
0
2
.
16
m
[3
].
OFDM tech
nolo
g
y
sp
lited
a h
i
gh
-rate d
a
ta stream in
to
sev
e
ral lower rat
e
p
a
rallel stream
s
th
at
are transm
i
tted
si
m
u
ltan
e
o
u
s
ly o
v
e
r a larg
e n
u
m
b
e
r
o
f
o
r
t
h
ogo
n
a
l sub
carriers. Becau
s
e
o
f
its orthog
on
ality
feature
,
the intra-cell interfe
re
ncecan be
a
voi
ded.
The m
acrocell
user e
qui
pm
ent (MUE) fa
r from
macr
ocel
l
base st
at
i
on (
M
B
S
) i
n
cu
rre
d
po
or i
n
d
o
o
r
capaci
t
y
i
n
cel
l
u
l
a
r
net
w
or
ks,
beca
use t
h
e
M
U
E s
u
f
f
ere
d
fr
om
hi
ghe
r
p
o
we
r
de
gra
d
at
i
o
n
(i
.e
., t
h
e
pa
t
h
l
o
ss
an
d p
e
n
e
tration
lo
ss of
walls are si
g
n
i
fican
t).
Altho
ugh
d
e
p
l
o
y
in
g m
o
re m
acro
cells see
m
s to
so
l
v
e th
is
p
r
ob
lem
,
th
e p
r
ob
lem
co
u
l
d
no
t b
e
actu
a
lly so
lv
ed
du
e to
t
h
e ex
tra in
terferen
ce in
trod
u
c
ed
b
y
th
ese
n
e
w b
a
se
st
at
i
ons (B
Ss
).
Furt
he
rm
ore,
t
h
e cost
i
s
also ot
he
r cri
t
i
cal
concer
n t
o
t
h
e ope
rat
o
r.
The de
pl
oy
m
e
nt
and
ope
rat
i
n
g ex
pe
nses
of
fem
t
ocel
l
are m
u
ch l
o
we
r t
h
a
n
t
h
at of m
acro
cells. To
so
lv
e th
is prob
lem
,
3
G
PP
propose
d
a sm
all cell, called
Femtocell. The fem
t
oce
ll
with
a low power, short rang
e, an
d
l
o
w co
st b
a
se
st
at
i
on.
D
u
e t
o
s
h
o
r
t
ra
n
g
e,
t
h
e
fem
t
ocel
l use
r
e
qui
pm
ent
(F
UE
) c
o
ul
d
not
i
n
t
e
rfe
re
d
by
F
U
Es i
n
ot
he
r
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-87
08
IJEC
E V
o
l
.
5, No
. 3,
J
u
ne 2
0
1
5
:
53
9 – 5
4
7
54
0
fem
t
ocell. The sam
e
channel c
oul
d
be efficiently reuse
d
for
m
u
l
tip
le ti
mes b
y
d
i
fferen
t femto
cells. Th
erefore,
fem
t
ocel
l
s
coul
d e
ffi
ci
ent
l
y
i
m
prove i
n
d
o
o
r
co
vera
ge
a
n
d
enha
nce t
h
e ca
paci
t
y
of
cel
l
u
l
a
r
net
w
or
ks.
Fem
t
ocel
l
net
w
o
r
k
s
are seen
as end-
use
r
h
o
t
spot
s p
o
si
t
i
o
n
e
d u
nde
r pl
a
n
n
e
d m
acrocel
l
net
w
o
r
ks a
n
d
o
p
e
rated in
m
acro
cellu
lar
p
r
ov
id
er’s licen
sed
sp
ectru
m
[4
, 5
]
. Th
e
fem
t
o
cell b
a
se station
co
nn
ected to co
re
net
w
or
k t
h
r
o
u
g
h
ca
bl
e o
r
di
g
i
t
a
l
subsc
r
i
b
e
r
l
i
n
e (
D
SL
)
bac
kha
ul
.
The
fe
m
t
ocel
l
base st
at
i
on
was a
pl
ug
-a
nd
-
pl
ay
de
vi
ce
a
n
d
c
oul
d be de
pl
oy
ed
by
som
e
su
bsc
r
i
b
er
s. W
i
t
h
t
h
i
s
, het
e
ro
ge
neo
u
s net
w
o
r
k
s
(Het
Net
s
) was
form
ed
. In
terferen
ce ex
isted
wh
en
two
UEs u
s
ed
a co
mmo
n
freq
u
e
n
c
y resou
r
ces in
cel
ls. Fig
u
re 1
illu
strates
a HetNet whe
r
e a m
acrocell
was
ove
rlaid with two
fem
t
oc
e
lls. In t
h
is Het
N
et, interfere
n
ce coul
d
be classifie
d
in
to
th
ree types:Femto
cell t
o
Fem
t
o
cell
i
n
terferen
ce
(Fi
g
ure 1
(1
)),
Macro
cell to
Femto
cell in
te
rferen
ce
(Fi
g
ure 1
(
3
) and (5
))
,
an
d Fem
t
oce
ll to
Macro
cell in
terferen
ce
(Figure 1
(2) and
(4
)). Th
e first typ
e
o
f
in
terferen
ce
was co
-tier i
n
terferen
c
e, wh
i
c
h
o
c
cured
between
n
e
ighb
oring
fem
t
o
cells. It was
u
s
ually
negl
ect
e
d
due
t
o
l
o
w t
r
ansm
it
po
we
r a
n
d
t
h
e pe
net
r
at
i
o
n l
o
ss
o
f
wal
l
s
. T
h
e
ot
he
r t
w
o
t
y
pes
of
i
n
t
e
r
f
e
r
enc
e
were
cr
oss
-
t
i
e
r
i
n
t
e
r
f
ere
n
ce,
whi
c
h c
o
ul
d
se
verel
y
deg
r
a
d
e
d
t
h
e ca
pacity of Het
N
ets.
The distance
between a
n
MUE and
an
MBS were u
s
ually
larg
er th
an
th
at o
f
a MUE and afem
tocell base st
ati
o
n
(FBS),
so
th
e MU
E
co
u
l
d
b
e
in
terfered
fo
rm
femto
cells. Th
e cro
ss-tier in
te
rferen
ce
was a im
p
o
r
tan
t
issu
e in
Het
N
ets.
In
th
is
p
a
p
e
r, we m
a
in
ly fo
cu
s
o
n
th
e in
terfere
n
ce mitig
atio
n
for cro
ss-tier in
terferen
ce.
M
a
ny
sol
u
t
i
o
n
s
have
bee
n
p
r
op
ose
d
f
o
r t
h
e i
n
t
e
rfe
rence m
i
t
i
g
at
i
on schem
e
si
n rece
nt
y
ears [
6
, 7]
.
In
strict fractional
fre
que
ncy re
use (St FFR) sc
hem
e
, each
m
a
cr
ocell only us
ed a half
ba
nd. On the
othe
r hand,
i
n
ot
her
f
r
act
i
o
nal
f
r
e
que
ncy
r
e
use
(i
.e.
S
o
F
F
R
,
a
n
d
FFR
-3
), eac
h
fem
t
ocel
l
used
i
n
s
u
ffi
ci
ent
su
b
b
an
ds
. T
h
e
abo
v
e sc
hem
e
s
m
a
y
severel
y
deg
r
a
d
ed t
h
e c
a
paci
t
y
of
Het
N
et
s. T
o
sl
o
v
e
t
h
i
s
pr
o
b
l
e
m
,
t
h
i
s
pa
per
pr
o
p
o
se
d a
reso
u
r
ce m
a
nagem
e
nt
schem
e
fo
r FU
Es. T
h
e FB
S wa
s d
e
si
gne
d t
o
ha
ve t
h
e cap
abi
l
i
t
y
t
o
sel
f-or
g
ani
ze.
Co
gn
itiv
e rad
i
o
(CR)
was an effectiv
e techn
i
qu
e to
pr
o
v
i
d
e
th
e cap
ab
ility o
f
self-o
rg
an
izatio
n
.
CR-en
h
a
n
ced
fem
t
ocells could obtain the i
n
form
a
tion of
m
acrocells by spectrum
se
nsing a
nd acces
s
the cha
nnels
without
co
op
eratin
g wi
th
m
acro
cells [8
,
9
,
10
].
In th
i
s
way
,
fem
t
ocel
l
s
coul
d
use s
u
bba
n
d
s e
ffi
ci
en
t
l
y
.
The rest
of t
h
e
pape
r was
or
gani
ze
d as f
o
l
l
o
ws
. I
n
Sect
i
o
n II
, t
h
e R
e
l
a
t
e
d w
o
r
k
wa
s p
r
esent
e
d.
I
n
Sect
i
o
n
I
II,
w
e
p
r
ese
n
t
e
d
de
t
a
i
l
s
of
o
u
r
p
r
op
ose
d
sc
hem
e
t
o
ha
ndl
e i
n
t
e
rfere
nce.
Si
m
u
l
a
t
i
on re
sul
t
s were
prese
n
t
e
d
i
n
Sect
i
on
IV
t
o
eval
uat
e
d sy
s
t
em
perf
orm
a
nce
of
o
u
r
p
r
op
ose
d
sc
hem
e
. Fi
nal
l
y
, Se
ct
i
on
V
concl
ude
d
t
h
i
s
pape
r.
Fi
gu
re
1.
I
n
t
e
r
f
ere
n
ce sce
n
a
r
i
o
of
Het
e
r
o
gen
e
ou
s
net
w
or
k
2.
RELATED WORKS
In t
h
i
s
cha
p
t
e
r
,
we i
n
t
r
od
uce
po
pul
a
r
fract
i
onal
f
r
eq
ue
nc
y
reuse schem
e
s [8]
[6]
[
12]
. The
n
we
in
trodu
ce a cog
n
itiv
erad
i
o
tech
no
log
y
in my literatu
re.
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
ECE
I
S
SN
:
208
8-8
7
0
8
Al
l
evi
at
i
ng
Int
e
rf
erence t
h
ro
ug
h C
o
gni
t
i
ve
Ra
di
o f
o
r L
T
E-
Adv
ance
d
N
e
t
w
ork
(Tsung
-Hu
i
Chua
ng
)
54
1
2.
1. T
r
adi
t
i
o
n
a
l
Freq
uenc
y
Pl
anni
n
g
In the traditional freque
n
cy pl
anni
ng sc
hem
e
, the
MUEs a
n
d FUEs can
us
e entire spectrum
in each
cel
l
.
M
U
Es an
d F
U
Es ca
n u
s
e ent
i
r
e sp
ect
r
u
m
wi
t
hout
a
n
y
i
n
t
e
r-cel
l
i
n
t
e
rfe
rence c
o
or
di
nat
i
o
n sc
he
m
e
s, so
th
is sch
e
m
e
is
also
called
No ICIC sch
e
m
e
.
Th
is si
m
p
le f
r
equ
e
n
c
y p
l
ann
i
ng
sch
e
m
e
max
i
m
i
zes
th
e to
tal
cellu
lar n
e
twork
cap
acity and
sp
ectru
m
u
tiliz
atio
n
,
b
u
t
fails to
gu
aran
tee the MUEs' p
e
rform
a
n
ce su
rroun
d
i
n
g
fem
t
o
cells. (e.g
., wh
en
th
e M
U
Es
u
s
e t
h
e same PRB with
FUE
surrou
nd
i
n
g fem
t
o
cells)
2.
2. Frac
ti
on
a
l
Frequenc
y R
e
use
2.
2.
1 S
t
ri
ct
Fr
acti
on
al
Freq
uency
Re
use
(
S
t F
F
R
)
In
Strict Fracti
o
n
a
l Frequ
e
n
c
y Reu
s
e (St FFR), a
m
acro
cell is
p
a
rtitio
ned
in
to
cell-center an
d
cell
-
edge
according to Re
fere
nc
e Signal
Receiving Powe
r
(RSRP)
reporte
d
by MUE
pe
riodically. An RSRP
t
h
res
hol
d i
s
de
ned
fo
r cel
l
-
ce
nt
er.
IfR
SR
P
r
e
p
o
r
t
e
d
by
t
h
e
M
U
Es are
hi
g
h
er t
h
e R
S
R
P
t
h
res
hol
d, t
h
e
M
B
S
considers that
theMUE
s
belong t
o
t
h
e cel
l-center.Others
MUEs
are
co
nside
r
ed as ce
ll-edge
MUEs
. The
available frequencyba
n
d is partitione
d i
n
to
4 subba
nds. B
ecause the
cell-
center MUEs
are not interfe
r
edby
any
ot
her cel
l
-
cent
e
r M
U
Es
, t
h
e cel
l
-
cent
e
r
M
U
Es use t
h
e
com
m
on subba
nd
. Ont
h
e ot
he
r han
d
, t
h
e cel
l
-
ed
ge
MUEs are clos
e to other cell-edge MUEs. In this case,
th
ecell-ed
g
e
MUEs sh
ou
ld
u
e
s th
e d
i
eren
tsu
b
b
a
nd
s in
d
i
ern
e
tm
acro
cell. To
mitig
atecro
s
s-tier in
t
e
rferen
c
e,
FB
Ss lo
cated
in th
e cell-cen
t
e
r cho
o
se sub
b
a
nd
s
assi
gne
d t
o
t
h
e M
U
Es i
n
t
h
e cel
l
-
ed
ge,
and
vi
ce ve
rs
a. Fo
r suc
h
a
sub
b
a
nd al
l
o
cat
i
on, t
h
e c
r
oss-t
i
e
r
in
terferen
c
e is
eectiv
ely
m
i
t
i
g
a
ted
.
2.
2.
2 S
o
f
t
Fra
c
ti
on
al
Freq
u
e
ncy
Reus
e (
S
o FF
R
)
Th
e cell p
a
rtitio
n
i
n
g
tech
n
i
q
u
e o
f
th
is sch
e
me is si
milar t
o
th
at of th
e St FFR.Ho
w
ev
er, th
e cell-
cen
ter MUEs
o
f
an
y
m
acro
c
ellisallo
wed
to u
s
e th
e sub
b
a
n
d
s
o
f
cell-ed
ge MUEs o
f
n
e
ig
hbo
ri
n
g
cells with
i
n
t
h
e cl
ust
e
r. F
o
r
a cl
ust
e
r
of
3
m
acrocel
l
s
, t
h
e
t
o
t
a
l
avai
l
a
bl
e
ba
nd
i
s
di
vi
de
d i
n
t
o
3 s
u
bba
nds
. T
h
ree s
u
b
-
b
a
n
d
assi
gne
dt
o t
h
e
t
h
ree cel
l
-
ed
ge t
o
a
voi
d i
n
t
e
rfe
re
n
ce be
tween m
acroc
ells. The cell-center MUEsof any
macrocell choose the s
u
bba
nd
s o
f
cel
l
-
e
dge
M
U
Es o
f
ne
igh
boring
cells with
in
th
e cl
u
s
t
e
r. To
m
i
tig
ate cro
s
s-
tier in
terferen
c
e, FBSs lo
cated
in
th
e cell-cen
ter n
e
ed
to
cho
o
s
e th
e sub
b
a
n
d
s
th
at are assig
n
i
ng
to
th
e
MUE in
the cell-edge,
and
vice
vers
a. In this sc
he
m
e
, the
FUEs in
m
acro
cell cell-cen
ter suffer fro
m
cro
s
s-tier
interfe
rence
.
T
h
ere
f
ore, the
SINR
of t
h
e
FUE i
n
m
acrocell cell-cen
ter is lower
t
h
an that of t
h
e FUEi
n
macrocell cell-edge
. Beca
use
the dista
n
ce
be
tween t
h
e
FU
E a
n
d
th
e
s
e
r
v
in
g
F
B
S
i
s
sh
o
r
te
r
t
h
an
th
e
d
i
s
t
a
n
ce
betwee
n the
FUE a
n
d the
MBS, the
SINR
of th
e
FUE
inmacrocell cell-center is a
cceptable.
2.
2.
3 Fr
acti
on
al
Freq
uenc
y
Reuse
-
3
(F
FR
-3
)
In
th
is sch
e
m
e
, th
e m
acro
cell co
v
e
rag
e
is p
a
r
titon
e
d
in
t
o
cell-cen
terand cell-ed
g
e
, inclu
d
i
ng
three
sect
ors eac
h. T
h
e ent
i
r
e
fre
q
u
e
ncy
i
s
di
vi
ded
i
n
t
o
f
o
ur s
u
b-
b
a
nd
s O
n
es
ub
ba
nds i
s
as
si
g
n
ed
t
o
M
U
E i
n
t
h
e
cel
l
-
cen
ter,
wh
ile th
e o
t
h
e
rs are assig
n
e
d
to
M
U
E in
cell-ed
ge.
To
di
m
i
ni
shcr
oss-t
i
e
r i
n
t
e
rf
e
r
ence
, FB
Ss c
h
o
o
se
subba
n
ds that
are not ue
sd
by the MUEs in thesam
e
macrocell subare
a
.
For exam
ple, whe
n
a
FBS is
located
i
n
a suba
rea, i
t
wo
ul
d
onl
y
us
e sub
b
an
d A
,
B
,
and D a
nd
excl
u
d
e su
b
b
a
nd C
si
nce su
b
b
an
d C
i
s
used
by
t
h
e
MUEs in th
is
su
barea. Co
mp
ared
with
So FFR, t
h
e
F
U
Es i
n
m
acroce
l
l
cel
l
-
cent
e
rw
oul
d
not
s
u
f
f
e
r
f
r
om
cross
-
tier interfere
n
ce since the MUEs
in
cell-ed
g
e
an
d
t
h
e FUEs in
m
acrocell cell-center are notus
i
ng the
sam
e
subba
nd
.
2.
3 Co
gni
t
i
v
e Ra
di
o
Co
gn
itiv
e rad
i
o
h
a
s b
e
en
consid
ered
as
a k
e
y
tech
no
log
y
fo
r in
terferen
ce m
i
tig
atio
n
i
n
fu
ture m
o
b
ile
n
e
two
r
k
.
C
o
gnitiv
e rad
i
o
is an
in
tellig
en
t rad
i
o
th
at is
aware of its su
rrou
n
d
i
ng
en
v
i
ron
m
en
t, wh
ich
sen
s
es
usef
ul
i
n
f
o
rm
at
i
on
fr
om
t
h
e
envi
ro
nm
ent
s
wi
t
h
u
s
er'
s
cha
nnel
cha
r
acteri
zation. The
n
,
BSs analyze it
and
ad
ju
st th
e syst
e
m
p
a
ram
e
ters
co
nfo
r
m
i
n
g
to certain
po
licies an
d
reg
u
l
ation
s
.
In
t
h
is p
a
per, we con
s
id
er th
at
FBS sh
av
e t
h
ree ab
ilities: rad
i
o
env
i
ron
m
e
n
ts sense,
rad
i
o
env
i
ron
m
en
t
s
an
alyzatio
n
,
an
dsyste
m
p
a
ra
m
e
ter
ad
ju
stm
e
n
t
. These th
ree ab
ilities are
d
e
scrib
e
d
in th
e
fo
llo
wi
n
g
threesub
sectio
n
s
.
2.
3.
1 Ra
di
o
E
n
vi
ro
nmen
ts Sense
FB
S can se
ns
e som
e
dow
nl
i
nk
refe
rence
si
gnal
s
t
o
m
oni
t
o
r t
h
e d
o
w
nl
i
nk t
r
ans
-
m
i
ssi
on
. Am
on
g
these downli
n
k refe
re
nce signals, the Refe
re
nce Si
gnal Re
ceiv
e Po
wer
(RSRP) is m
o
st im
p
o
r
tan
t
fo
r
reso
urce
man
a
g
e
m
e
n
t
an
d in
terferen
ce m
i
tig
atio
n
.
Th
eRSRP is
t
h
e a
v
era
g
e
power of RE
that carry cell-s
p
ecific
R
e
fere
nce Si
g
n
a
l
s
(C
R
S
) ove
r
t
he ent
i
r
e ban
d
w
i
d
t
h
. The C
R
S
are pre
dne
d
si
gnal
s
occ
u
py
i
ng speci
fi
c res
o
u
r
ce
ele-m
e
n
t
s fo
r
ch
ann
e
l estim
a
tio
n
.
Th
e CRS tran
sm
itted
in
ev
ery down
l
i
n
k su
bfram
e
an
d in
ev
ery reso
urce
bl
oc
k i
n
t
h
e f
r
e
que
ncy
d
o
m
a
i
n
, t
h
us co
veri
ng t
h
e ent
i
r
e c
e
l
l
band
-wi
d
t
h
. The R
S
R
P
p
r
o
v
i
d
es i
n
f
o
rm
at
i
on
about si
gnal st
rengt
h that im
plies the
di
stance
betwee
n
recei
ver and tra
n
sm
itter.
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-87
08
IJEC
E V
o
l
.
5, No
. 3,
J
u
ne 2
0
1
5
:
53
9 – 5
4
7
54
2
2.
3.
2 Ra
di
o
E
n
vi
ro
nmen
ts An
al
yz
ati
o
n
Aft
e
r
FB
S se
n
s
es radi
o e
nvi
r
onm
ent
s
, FB
S
can o
b
t
a
i
n
usef
ul
i
n
f
o
rm
at
i
on fr
om
it
s surr
o
u
ndi
ng cel
l
s
.
Th
en
, FBS an
alyzes th
ese in
fo
rm
atio
n
s
to
ob
tain
p
a
ram
e
te
rs th
atcan
b
e
used
in
resou
r
ce allo
catio
n
sch
e
m
e
.
In [4], the a
u
thor
s propose
d a non-cooperative path l
o
ss estim
a
tion
m
e
thod. T
h
e
FUEs inde
pe
nde
ntly
esti
m
a
te th
e p
a
th
lo
ss
b
e
tween
itself and
M
U
Es i
n
h
i
erar
c
h
ical net
w
ork.
The
basic i
d
ea
is that the
FUE
sens
es
t
h
e b
r
oa
dcast
i
ng
si
g
n
al
f
r
om
t
h
eM
B
S
, a
n
d
dem
odul
at
es t
h
e c
h
an
nel
ass
i
gnm
ent
i
n
f
o
r
m
at
i
on an
d a
d
apt
i
v
e
m
odulationa
nd coding (AMC
) settings for t
h
e MUE.
Ad
a
p
tive
m
odulation and coding is a keytechnology for
channel quality
m
a
intenance
.
AMC
provides the exibility to
m
a
tchthe
m
odulation-c
odi
ng sc
hem
e
to the
avera
g
e c
h
a
nnel conditions
for each
user.
ThisAMC is
used t
o
c
o
nstruct m
odulation
and c
odi
ng sc
hem
e
(MCS). The
MCS containst
h
e
path l
o
ss
between MBS a
n
d MUE in
formatio
n
.
Fo
r
exa
m
p
l
e, th
e sm
all p
a
th
l
o
ssl
eads t
o
hi
ghe
r si
g
n
al
-t
o-
i
n
t
e
rfe
rence
-
pl
us-
n
oi
se rat
i
o
(SI
N
R
)
, an
d
vi
ce ver
s
a. T
h
e
M
C
Scan be
m
a
ppi
n
g
t
o
pat
h
l
o
ss, a
l
t
hou
g
h
M
C
S
sel
ect
i
on m
a
y
al
so be a
ffect
e
d
by
s
o
m
e
ot
her fact
o
r
s
(e.
g
.,
fadi
ng
, sha
d
o
w
i
n
g,
noise
, and som
e
tim
e
s
interference). The M
U
E'
s transm
it
po
we
r can
be estim
a
ted from
the M
C
S info
rm
atio
n
by SINR form
ula, while FUE can se
nse received
powe
r from
MUEs dir
ectly. In t
h
is way, the FUE can
esti
m
a
te
th
e v
a
l
u
e
o
f
th
e
p
a
th lo
ss
b
e
tween
FUEs and
MUEs.
2.3.3 Sys
t
em
Par
a
meter
Adjustment
In
ord
e
r to
imp
r
ov
e cellu
lar
n
e
two
r
k
cap
aci
ty, BS
h
a
s t
o
ad
ju
st cellu
lar network
syste
m
p
a
ram
e
ters
(i
e., FB
S t
r
a
n
s
m
i
t
powe
r
,
UE
t
r
ansm
it
powe
r
, an
d R
B
sche
dul
e
)
eci
ent
l
y
. Aft
e
r B
S
se
nse
s
radi
o e
nvi
ro
n
m
ent
s
and analyze it,
BS obtains
use
f
ul
pa-ram
eters about
ra
di
o e
n
vi
r
onm
ent
s
. F
o
r e
x
am
pl
e, i
n
[
4
]
,
t
h
e
FB
S
o
b
t
ai
ns
th
e p
a
th
lo
ssbetween
th
e FB
S an
d
in
terfered
MUEs
, s
o
the FBS can schedule
uno
ccupied
RB b
y
MU
Es to
FUEs
or adjust its tran
sm
i
t
p
o
wer to
d
i
min
i
sh
cro
ss-
t
i
er in
terferen
c
e. FBSscan
ad
ju
st th
ese p
a
ram
e
ters
p
e
ri
o
d
i
cally to
o
p
tim
ize th
e HeNet.
3.
SYSTE
M
MO
DEL
Th
e syste
m
m
o
d
e
l o
f
ou
r sch
e
me is
il
lu
strated
in
Fi
g
u
re 2
,
i
n
clud
ing
illu
strate a h
i
erarch
ical n
e
two
r
k
wi
t
h
o
u
r
pr
o
p
o
se
d schem
e
depl
oy
m
e
nt
and
a
m
acrocel
l
wi
t
h
o
u
r
pr
o
p
o
se
d schem
e
depl
oy
m
e
nt
.The
sy
st
e
m
m
odel
cont
ai
n
e
d se
ven M
B
Ss wi
t
h
t
h
ree
12
0°
di
rect
i
o
nal
t
r
an
sm
it
ant
e
n
n
as at
t
h
e
cent
e
r
of eac
h cel
l
respect
i
v
el
y
,
a
s
sho
w
n i
n
Fi
gu
re 3.
A R
e
f
e
rence Si
gnal
R
eci
eved P
o
w
e
r (R
SR
P) [
1
1
]
i
s
defi
ne
d fo
r cel
l
-
centerin every
cell. If RSRP reported by
the
MUEs a
r
e
hi
g
h
er
R
S
R
P
t
h
re
shol
d,
t
h
e
M
B
S co
nsi
d
ere
d
t
h
at
t
h
e
MUEs bel
o
ng to the cell-center. Othe
rs MUEs are c
ons
i
d
ere
d
as cell-edge MUEs
[4
].
I
n
th
is w
a
y,
ev
ery
macrocell cove
rage
is pa
rtitioned into cell-c
e
nt
er a
n
d cell-edge
, incl
udi
ng three sect
ors
each.
Fi
gu
re
2.
Sy
st
em
m
odel
Thi
r
t
y
FB
Ss a
r
e depl
oy
ed
uni
fo
rm
ly
i
n
every
m
acrocel
l
.
Th
e M
U
E w
o
ul
d
suf
f
er
fr
om
seri
ous c
r
o
ss-
tier in
terferen
ce b
ecau
s
e th
e MU
E
is
c
l
o
s
ed
to
F
B
Ss
.
T
h
e
r
e
f
o
r
e,
in
ter
f
e
r
e
n
c
e
c
o
u
l
d be
c
o
n
s
id
er
ed
in
th
e
achi
e
va
bl
e cha
nnel
ca
paci
t
y
of M
U
E.
The
achi
e
va
bl
e cha
nnel
ca
paci
t
y
of M
U
E c
o
ul
d
be c
o
m
put
ed
by
t
h
e
Sha
n
non’s
capacity form
ula as
)
1
(
log
10
x
x
SINR
BW
C
(1
)
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
ECE
I
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:
208
8-8
7
0
8
Al
l
evi
at
i
ng
Int
e
rf
erence t
h
ro
ug
h C
o
gni
t
i
ve
Ra
di
o f
o
r L
T
E-
Adv
ance
d
N
e
t
w
ork
(Tsung
-Hu
i
Chua
ng
)
54
3
whe
r
e
x
C
indicated the theoretically ach
ievabl
e channel capacity ofMUE
x
.
BW
indicated t
h
e
available
ban
d
w
i
d
t
h
fo
r
com
m
uni
cat
ion
.
x
SINR
indicated the signal-to-i
n
terfe
re
nce-
pl
u
s
-n
oi
se rat
i
o
of t
h
eM
UE
x
.Thesi
gnal
-
t
o
-i
nt
erfe
re
nce-
pl
u
s
-n
oi
se rat
i
o
of
t
h
e
M
U
E
x
can be re
prese
n
ted a
s
K
i
L
j
j
x
j
i
x
i
m
x
m
x
G
P
G
P
N
G
P
SINR
11
,
,
,
(2
)
whe
r
e
m
P
indicated the transm
iting power
of M
B
S
m
.
m
x
G
,
ind
i
cated th
ech
an
n
e
l
g
a
in
b
e
tween
the MUE
x
an
d
its serv
ing MBS
m
.
N
i
ndi
ca
t
e
dt
he t
h
erm
a
l
noi
se
po
wer
.
i
P
indicated t
h
e transm
it
powe
r
of i
n
t
e
r
f
er
i
n
g
MBSs
i
.
K
in
d
i
cated
th
e to
tal n
u
m
b
er o
f
in
terfering
MBSs.
L
i
ndi
cat
ed t
h
et
ot
a
l
num
ber of i
n
t
e
rfe
ri
n
g
FUE
s
with
in
th
e sam
e
MBS.
j
P
i
ndi
c
a
t
e
dt
he t
r
a
n
sm
i
t
powe
r
o
f
i
n
t
e
rfe
ri
n
g
FB
Ss
j
.
i
x
G
,
indicated t
h
e channel
gai
n
bet
w
ee
n t
h
e M
U
E
x
an
d interfe
rin
g
M
B
S
i
, and
j
x
G
,
is the channel gai
n
between the M
U
E
x
and
interfe
rin
g
FB
S
j
.
In [8
],
th
e
au
tho
r
s assu
med
th
at
no
o
t
he
r cell in
terfers th
is se
nse
d
MUE. The
r
efore,
K
i
L
j
j
x
j
i
x
i
G
P
G
P
11
,
,
canbe
i
g
no
re
d.
The ac
hieva
b
le
cha
nnel c
a
pac
ity of FUE ca
n be
re
prese
n
ted as
)
1
(
log
10
y
y
SINR
BW
C
(3
)
whe
r
e
y
C
indicated the t
h
eoretically achie
va
ble
channel ca
paci
ty of
FUE
y
.
y
SINR
indicated t
h
e si
gnal-to-
i
n
t
e
rfe
rence
-
pl
us-
n
oi
se rat
i
o
of t
h
e
FUE
y
. T
h
esi
g
nal
-
t
o
-i
nt
erfe
rence
-
pl
us-
noi
se
rat
i
o
o
f
t
h
e FUE
y
can be
represe
n
ted as
K
i
L
j
j
y
j
i
y
i
f
y
f
y
G
P
G
P
N
G
P
SINR
11
,
,
,
(4
)
whe
r
e
f
P
indicated the transm
it p
o
we
r of FBS
f
.
f
y
G
,
indicated the channelgai
n be
tween the FUE
y
and
its serv
ing
FB
S
f
.
N
i
ndi
cat
ed
t
h
et
herm
al
noi
se po
we
r.
i
P
in
dicated
th
e transmit p
o
w
er
o
f
in
terferi
ng
MBSs
i
.
K
ind
i
cated
th
e to
tal
n
u
m
b
e
r
o
f
in
t
e
rfering
MBSs.
L
indicated t
h
e
t
otal num
b
er
of interferi
n
g
FUEs
with
in th
e sam
e
MBS.
j
P
is th
e transm
i
t
p
o
wer of in
terfering
FB
Ss
j
.
i
y
G
,
indicated t
h
e c
h
annelgai
n
bet
w
ee
n t
h
e F
U
E y
a
n
d i
n
t
e
rfe
ri
n
g
M
B
S
i
., a
n
d
j
y
G
,
i
s
t
h
e cha
nnel
gai
n
bet
w
ee
n t
h
e
FU
E
y
and
interfe
rin
g
FB
S
j
.
4.
PROP
OSE
D
SCHE
ME
Based
o
n
fractio
n
a
l freq
u
e
n
c
y reu
s
e (FFR) sch
e
m
e
, to
tal b
a
n
d
were
p
a
rtitio
n
e
d in
to sev
e
ral
subba
n
ds accordi
ng to t
h
e location of
eve
r
y UE. If the re
s
o
urce bl
ocks (RBs) were e
xhausted in
fem
t
ocells,
fem
t
ocel
l
s
woul
d
use ot
her
sub
b
a
n
ds. I
n
t
h
i
s
way
,
M
U
Es su
ffe
red
fr
om
cross-tier
interfe
rence
.
F
o
r this
reaso
n
, t
h
e
p
r
o
p
o
sed sc
he
m
e
i
n
t
r
od
uced
C
R
-
enha
nce
d
fem
t
ocel
l
s
to pr
o
v
i
d
e R
B
s l
i
s
t
s
of cross
-
t
i
e
r
i
n
t
e
rfe
rence
R
B
s. I
n
ou
r
p
r
o
p
o
se
d sc
hem
e
, we
defi
ned
si
x
set
s
o
f
R
B
s
:
M
：
Th
e set of t
o
tal RBs o
f
a macro
cell
i
M
：
The
set of R
B
s of m
acrocell suba
rea
ac
cording to FFR-3 sc
hem
e
, where
}
,
,
,
,
,
{
,
3
2
1
3
2
1
E
E
E
C
C
C
i
.
That is,
i
E
E
E
C
C
C
i
M
M
}
,
,
,
,
,
{
,
3
2
1
3
2
1
, a
s
s
h
ow
n i
n
Fi
gu
re
3.
j
F
：
The set of R
B
s of fem
t
ocell j according to FFR-3 s
c
hem
e
, where is the
fem
t
ocell sequence num
b
er per
macrocell.
'
j
F
：
The
set
o
f
R
B
s of
M
U
E
s
u
r
r
o
u
ndi
ng
fem
t
ocel
l
j
R
：
Th
e set of can
d
i
d
a
te RBs for fem
t
o
cell
U
：
The
set of R
B
s in
use
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-87
08
IJEC
E V
o
l
.
5, No
. 3,
J
u
ne 2
0
1
5
:
53
9 – 5
4
7
54
4
Wh
en
th
e RB
s were exh
a
usted
in
a fem
t
o
cell (i.e.,
U
F
j
),
t
h
e f
o
l
l
o
wi
ng
pr
oce
d
u
r
e wa
s
exercise
d at FBS:
Step1
:
Wh
en
U
F
R
j
j
, th
e FBS sen
s
ed
so
m
e
d
o
wn
lin
k
reference sig
n
a
ls to
mo
n
itor th
e
do
w
n
l
i
nk t
r
a
n
s
m
i
ssi
on. Acc
o
r
d
i
n
g t
o
t
h
e
no
n-c
o
ope
rat
i
v
e
pat
h
l
o
s
s
est
i
m
a
t
i
on m
e
t
hod [
8
]
,
t
h
e FB
S
ob
t
a
i
n
e
d
u
s
efu
l
link
param
e
ters. The lin
k
p
a
rameters in
cl
u
d
e
d th
e
d
o
wn
link
/
up
lin
k chann
e
l ind
e
x and
ad
op
t
do
w
n
l
i
nk/
upl
i
n
k m
odul
at
i
o
n a
nd c
o
di
n
g
sc
he
m
e
(M
C
S
) by
dem
odul
at
i
n
g
br
oa
dcast
i
n
g
si
gnal
fr
om
t
h
e M
B
S.
Ot
he
rwi
s
e,
t
h
e
pr
oce
d
u
r
e
pr
oc
eeds t
o
St
e
p
2.
Step2: T
h
e fe
mtocell analyzed above pa
ram
e
te
rs accordi
ng to t
h
e
non-
cooperative path los
s
esti
m
a
t
i
o
n
m
e
t
h
od
. Th
en
, th
e
FBS ob
tain
ed
t
h
e p
a
t
h
lo
ss
be
t
w
een M
U
Es a
nd i
t
s
el
f.
Ot
he
r
w
i
s
e, t
h
e
pr
oce
d
u
r
e
pr
ocee
ds t
o
St
e
p
3.
Step
3
:
Ob
tain
ed
j
R
fr
om
U
F
M
R
j
j
'
If
j
R
, th
e
femto
cell r
eallocated a RB in
j
R
to F
U
E.
In
Fig
u
re
3
,
,
3
,
2
,
1
{
RB
RB
RB
R
j
}
3
{
}
5
,
4
{
}
2
,
1
{
}
5
,
4
RB
RB
RB
RB
RB
RB
RB
. The
r
efore, the fem
t
ocell rea
llo
cated
RB3
t
o
FUE3
.
After
th
e
fem
t
o
cell rello
cated
RBs, th
e p
r
o
c
ed
ure was termin
ated
. No
te th
at MUE3 an
d
FUE3
u
s
ed
th
e sam
e
RB
(i.e.,
R
B
3
). B
eac
use
FUE
3
was
far
fr
om
M
U
E3,
M
U
E3
co
ul
d
not
se
nse
t
h
e
d
o
w
n
l
i
n
k si
g
n
al
bet
w
ee
n
FUE
3
a
n
d
its serv
ing
FB
S. Th
us, t
h
e cro
ss-tier in
terferen
ce wasm
itig
ated
.
If it
wasun
f
o
r
t
u
n
a
tely,
j
R
, th
e fem
t
o
cell
coul
d n
o
t
ha
ve
any
can
di
dat
e
R
B
for
FUE
3
.
That
i
s
, n
o
m
a
t
t
e
r whi
c
h R
B
s
be use
d
by
t
h
e FU
E (i
.e.
,
FUE
3
)
,
o
t
h
e
r UEs will
b
e
in
terfered. Th
e p
r
o
c
ed
ure p
r
o
ceed
s
to
Step
4
.
Step
4
:
Ob
tain
ed
j
R
fr
om
U
M
R
j
Th
en
, th
e FBS sh
ou
ld
redu
ce d
o
wn
link
transmit p
o
w
er
.
In th
is way, th
e cro
s
s-tier in
terferen
ce is
al
so m
i
ti
gat
e
d.
5.
PERFO
R
MA
NCE E
V
ALU
A
TIO
N
We e
v
al
uat
e
d
sy
st
em
perf
orm
a
nce o
f
o
u
r
pr
o
p
o
s
ed
schem
e
t
h
ro
u
gh
si
m
u
l
a
ti
on.
The m
a
jo
r
si
m
u
latio
n
p
a
ra
m
e
ters are lis
ted
in
Tab
l
e 1
.
W
e
d
e
fi
n
e
d
cell-cen
ter MUE as th
e MUE with
d
i
stan
ce to
its
servi
n
g
B
S
l
e
s
s
t
h
a
n
or e
q
ual
t
o
40
0 m
e
t
e
rs.
Li
ke
wi
se
,
when
th
e UE is m
o
re th
an
4
0
0
meters away fro
m
th
e
BS, it is ca
lled
a cell-
ed
g
e
MU
E. Th
e pr
oposed
sch
e
m
e
is
co
m
p
ar
ed
w
ith St FFR, So
FFR, FFR-3
, and
No
in
ter-cell in
terferen
ce co
ord
i
natio
n
(IC
IC) sch
e
m
e
s. W
e
as
s
u
m
e
that 1/2 of RBs (i.e., 24
RBs) are allocated to
cel
l
-
edge
M
U
E
s
i
n
a
b
ove
FFR
schem
e
s.
Figure 3 showed the variation in avera
g
e FUE’s
thro
ugh
pu
t with
v
a
rying
av
erag
e nu
mb
er of FUEs
per
fem
t
ocell. Whe
n
t
h
e a
v
erage
num
ber
of FUE
s
ev
ery fe
m
t
ocell were
m
o
re than
10 FUE
s
, s
o
m
e
FUEs
waited
u
n
til some RBs were av
ailab
l
e. FFR sch
e
m
e
s (i.e. St FFR, So
FFR,
an
d
FFR-3) sev
e
rely d
e
grad
ed
th
e
FUE
’
s throughput as t
h
e ave
r
age num
b
er o
f
FUEs
per
fem
t
ocel
l
i
n
creasi
n
g.
Ho
we
ver
,
o
u
r
pr
o
pose
d
sc
hem
e
has
bat
t
e
r F
U
E
’
s t
h
r
o
u
g
h
p
u
t
whe
n
t
h
e a
v
era
g
e
num
ber
of
F
U
Es
pe
r fem
t
ocel
l
i
n
creasi
n
g.
Tabl
e 1. Si
m
u
lat
i
on
Pa
ram
e
t
e
rs
Evaluation Warning : The document was created with Spire.PDF for Python.
I
J
ECE
I
S
SN
:
208
8-8
7
0
8
Alleviating
Int
e
rference th
ro
ug
h C
o
gnitive
Ra
dio f
o
r L
T
E-
Adv
ance
d
N
e
t
w
ork
(Tsung
-Hu
i
Chua
ng
)
54
5
Fi
gu
re 4 sh
o
w
ed t
h
e cum
u
l
a
ti
ve di
st
ri
b
u
t
i
o
n
funct
i
on (C
D
F
) o
f
FUE t
h
r
o
u
g
h
p
u
t
wi
t
h
f
i
ve di
ffe
re
nt
schem
e
s. Thi
s
fi
g
u
re s
h
owe
d
t
h
at
ou
r
pr
o
p
o
s
ed sc
hem
e
has bat
t
e
r F
U
E
’
s
t
h
r
o
u
g
h
p
u
t
t
h
an St
FFR
, S
o
FFR
,
and FFR-3. T
h
e proposed s
c
hem
e
got the better perf
ormance of FUE
throughput
, because FUE coul
d use
m
o
re R
B
s
. Ho
weve
r,
N
o
IC
I
C
schem
e
had
bat
t
e
r t
h
ro
u
g
h
put
t
h
an
o
u
r
p
r
op
ose
d
sc
hem
e
beca
use FB
S
s
co
ul
d
allo
cate all R
B
s with
ou
t any ICIC sch
e
mes. Gen
e
rally sp
eak
i
ng
, No
ICIC sch
e
m
e
u
s
u
a
lly h
a
d
th
e larg
est
FUE
’
s t
h
roughput
(i.e.,
beca
use FBSs
can al
locate all
RBs
witho
u
t a
n
y
IC
IC sc
hem
e
s). M
U
Es s
u
ffe
re
d
fr
o
m
strong interference
from
femtocells, s
o
No
ICIC
is n
o
t
fair in
a HetNet.
T
h
ere
f
ore, No
ICIC was
not
practical
i
n
Het
N
et
s.
O
u
r
pr
o
pose
d
sc
hem
e
was cl
osed t
o
t
h
e F
U
E
’
s t
h
r
o
u
g
h
p
u
t
o
f
N
o
IC
IC
sc
h
e
m
e
. In ot
her
wo
rd
s,
ou
r
pr
o
pos
ed
s
c
hem
e
had
bet
t
e
r t
h
ro
u
g
h
p
u
t
i
n
F
U
E
’
s t
h
r
o
u
g
h
p
u
t
.
Fi
gu
re
3.
Ave
r
age F
U
E
t
h
r
o
u
g
h
p
u
t
(
K
bps
)
Fig
u
re 5
sho
w
ed
th
e CDF of MUE th
ro
ugh
pu
t with
differe
n
t schem
e
s. This figure s
h
owed that our
pr
o
pose
d
sche
m
e
has bat
t
e
r M
U
E’s t
h
r
o
u
g
h
p
u
t
t
h
an
No
IC
IC
, St
FFR
, and S
o
FF
R
.
In FFR
-
3
,
l
a
rge
t
h
r
o
u
g
h
p
u
t
o
f
M
U
Es wa
s o
b
s
erve
d
due t
o
t
h
r
o
ug
h
put
wi
t
h
di
ffe
rent
sc
h
e
m
e
s. Ou
r p
r
o
pos
ed sc
hem
e
had t
h
e
larg
est to
tal th
rou
ghp
u
t
. The th
roug
hpu
t o
f
FFR-3
was s
m
aller th
an
No
ICIC du
e
to
li
m
i
ted
sp
ectru
m
allo
catio
n
of fe
m
t
o
cell. Wh
en
RBs were exh
a
usted
in
th
e
fem
t
o
cell, th
e
FBS d
i
d
n
o
t
al
lo
cate o
t
h
e
r RBs th
at
wo
ul
d
not
ca
us
ed st
ro
n
g
i
n
t
e
r
f
e
rence t
o
nei
g
h
b
o
r
M
U
Es
. H
o
weve
r, t
h
e t
h
r
o
ug
h
put
o
f
N
o
I
C
IC
i
s
sm
all
e
r t
h
an
our
propos
ed s
c
hem
e
because
MU
Es suffe
r from
strong
inte
rfe
re
nce
from
neighbor fem
t
ocell.
Fig
u
r
e
4
.
CD
F
o
f
FUE thro
ugh
pu
t
(
K
bp
s)
Fi
gu
re
5.
C
D
F
of
M
U
E t
h
r
o
u
g
h
p
u
t
(
K
bps
)
Tabl
e 2 sh
o
w
s
t
h
at
t
o
t
a
l
t
h
ro
ug
h
put
wi
t
h
di
ffe
rent
schem
e
s. Ou
r
p
r
o
p
o
se
d schem
e
has t
h
e l
a
rgest
to
tal th
ro
ugh
pu
tin
t
h
is tab
l
e. Th
e throug
hpu
t
o
f
FFR-3 was sm
allerth
a
n
No
ICIC
du
e to
lim
i
t
ed
spectru
m
allo
catio
n
o
f
femto
cell. Wh
en RBs were exhau
s
ted32
in
th
e
fem
t
o
cell, th
e FBS d
i
d
no
t allo
cate o
t
h
e
r RB
s th
at
Evaluation Warning : The document was created with Spire.PDF for Python.
I
S
SN
:
2
088
-87
08
IJEC
E V
o
l
.
5, No
. 3,
J
u
ne 2
0
1
5
:
53
9 – 5
4
7
54
6
wo
ul
d
not
ca
u
s
ed st
r
o
n
g
i
n
t
e
rfe
rence t
o
nei
g
h
b
o
r M
U
Es
.
Howev
e
r, th
e th
ro
ugh
pu
t of No
ICIC is smaller
thanour proposed
schem
e
because M
U
Es suffered
from
seri
ous
interference
from
neighboring fem
t
ocell.
Tabl
e 2.
T
o
t
a
l
Thr
o
ug
h
put
6.
CO
NCL
USI
O
N
In t
h
i
s
pape
r,
we p
r
o
p
o
sed
a no
vel
schem
e
for
d
o
w
n
l
i
n
k IC
IC
i
n
LT
E-ad
va
nced
ne
t
w
o
r
ks
. T
o
allev
i
ate in
terferen
ce, we
u
s
ed
cogn
itiv
e rad
i
o
tech
n
i
ques to
sen
s
e
rad
i
o
en
v
i
ron
m
en
t and
adju
st RB
allo
catio
n
.
In
ou
r propo
sed
sch
e
m
e
, w
e
sacri
f
iced
a
little MU
E’s through
pu
t
(i.e., 4.8%)
for
fem
t
o
c
e
ll. For a
fem
t
ocel
l
,
t
h
e
m
o
re R
B
s
coul
d be
use
d
. T
h
e
FUE’
s t
h
r
o
ug
hp
ut
was t
hus
im
pro
v
ed
(i
.e.,
13.
1%
). Si
m
u
l
a
t
i
o
n
resu
lts sh
owed th
at o
u
r
p
r
op
o
s
ed
sch
e
m
e
can
ach
iev
e
b
e
tter to
tal th
ro
ugh
pu
t co
m
p
ared
with
o
t
h
e
r ICIC
schem
e
s.
ACKNOWLE
DGE
M
ENTS
Th
e wo
rk
o
f
Men
g
-H
sun
Tsai w
a
s
spo
n
s
or
ed b
y
NSC
102
-22
21-
E-00
6-
113-
MY2
.
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e
d
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sal Ter
r
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.
2010
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L.
H.
H. Claussen
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l
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l
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t
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mt
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c
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e
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ire
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M.
D.
S.
R.
J.
G. Andrews
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,
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em
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K.
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Saquib,
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., “Fraction
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EEE
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Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE
ISS
N
:
2088-8708
Al
l
evi
at
i
ng
Int
e
rf
erence t
h
ro
ug
h C
o
gni
t
i
ve
Ra
di
o f
o
r L
T
E-
Adv
ance
d
N
e
t
w
ork
(Tsung
-Hu
i
Chua
ng
)
54
7
BIOGRAP
HI
ES OF
AUTH
ORS
Tsung-H
ui C
h
u
a
ng
is a Ph.D. Candidatein Dep
a
rtment
of Computer Science an
d Information
Engineering, National Cheng K
ung University
(NCKU). He re
ceiv
e
d the M.S degrees from
National Ping
Tung University
(
N
PU
). His current research
topic
includ
e cong
estion of
MTC dev
i
ces and
MTC
d
e
vices trigg
e
ring
.
Guan-Hong Chen
was gradu
a
ted from Department of
Computer Scien
ce and Information
Engineering, National Cheng
Kung University
(
N
C
KU). He is f
u
lfilling his
mandator
y
militar
y
service now.
M
e
ng-H
sun Ts
ai
is a
n
a
ssista
n
t profe
ssor in Depa
rtme
nt of Co
mputer Science
and Information
Engineering, National Ch
eng Ku
ng University
(
N
C
KU). He rec
e
ived
the B
.
S
.,
t
h
e M
.
S
.
and
the
Ph. D. degrees
from
National Chiao Tung
University
(NCTU) in 2002, 2004 and 2009,
res
p
ect
ivel
y.
He
was
a vis
iting s
c
holar
at Univ
er
sity
of
Southern
California (USC) during July
–
August 2012.
He was a recipient of the Exp
l
oration Res
earch Award of
Pan Wen Yuan
Foundation in 2
012 and th
e Outstanding Contr
i
b
u
ti
on Award fro
m IEEE Taip
ei
Section
in 2010.
His c
u
rre
nt re
se
arc
h
inte
re
sts in
clude design
and analy
s
is of mobi
le networks, mobile
computing
and perfo
rmance modeling.
Chu
n
-Lung Lin
rec
e
ived
th
e B.
S. degre
e
in
m
a
t
h
em
atics from
Nationa
l Tsing
Hua Universit
y
,
Hsinchu, T
a
iwa
n
, R.O.C
.,
in 20
01, the M.S. degree in
comput
e
r
scienc
e from
Nationa
l Chiao
Tung University, Hsinchu, Taiw
an, in 2003,
an
d the Ph.D. deg
r
eein co
mputer science from
National Tsing Hua Universit
y
,
in 2010. He join
ed
the Industri
a
l
Technolog
y
Research Institu
te
(ITRI), Hs
inchu
,
Ta
iwan, in 20
10 as
a res
ear
ch
er
.His
curren
t
re
s
earch int
e
res
t
s
includ
e im
age
processing,
video processing
, sensor ne
tworks and ICT for
disaster response.
Evaluation Warning : The document was created with Spire.PDF for Python.