TELKOM
NIKA Indonesia
n
Journal of
Electrical En
gineering
Vol.12, No.7, July 201
4, pp
. 5514 ~ 55
2
1
DOI: 10.115
9
1
/telkomni
ka.
v
12i7.481
8
5514
Re
cei
v
ed O
c
t
ober 7, 20
13;
Revi
se
d Ma
rch 22, 20
14; Acce
pted April 7, 2014
A Study
of Cognitive Technology OFDM System and
Frame Structure
Hua Hou, Wei Zhang*
Hebe
i Univ
ersi
t
y
of Engi
ne
eri
ng, schoo
l of
in
formation & en
gin
eeri
ng, He
b
e
i Ha
nda
n Ch
i
n
a
*Corres
p
o
ndi
n
g
author, e-ma
i
l
: z
w
e
i
h
ebe
i@1
63.com
A
b
st
r
a
ct
For mob
ile
co
mmu
n
icati
o
n
s
ystem w
i
th
mul
t
i-service
of multipl
e
users,
s
pectru
m
utili
z
a
t
i
on
rate i
s
low
and
user'
s
QoS req
u
ire
m
e
n
ts ne
ed to
be i
m
prov
ed.
T
he p
aper
pr
opos
ed
a cros
s-layer
base
d
o
n
cogn
itive ra
dio
techno
logy
an
d OF
DM techn
o
lo
gy mod
e
l a
nd d
e
sig
n
e
d
th
e core tec
hno
l
ogy of this fra
m
e
structure
mo
d
e
l
such
as
service
div
i
sio
n
, spec
tru
m
s
ensi
ng
an
d s
pectru
m
ag
gregati
o
n
in
d
e
tail
.
Co
mpre
he
nsiv
e ju
dg
me
nt thr
oug
h the s
e
rvi
c
e ne
eds
of
dif
f
erent users, a
nd the
s
pectru
m
h
o
l
e
s ju
dg
ment,
not only
m
e
et different user
’
s
QoS, but also im
prov
e spectrum
utili
z
a
tion and increase the syste
m
suitab
ility. Fina
lly, the simulati
on an
alysis of the mo
de
l
’
s pe
rforma
nce
s
h
o
w
s that the
mo
del
can
n
o
t o
n
l
y
reaso
nab
le us
e of the spectrum h
o
l
e
s, and
better meet the
user
’
s
QoS re
quir
e
ments.
Ke
y
w
ords
:
cognitiv
e
radio; OFDM; syst
em
m
o
del; fram
e s
t
ructure
Copy
right
©
2014 In
stitu
t
e o
f
Ad
van
ced
En
g
i
n
eerin
g and
Scien
ce. All
rig
h
t
s reser
ve
d
.
1. Introduc
tion
In re
ce
nt yea
r
s,
with th
e
rapid
develo
p
m
ent of
mobi
le commu
nication te
chn
o
l
ogy, the
deman
d for u
s
er
data tra
n
s
missio
n rate
s and b
and
wi
dth has in
cre
a
se
d. At the same time, t
h
e
probl
em of
radio sp
ectru
m
re
so
urce
s scarcity ha
s b
een
mo
re an
d mo
re
se
riou
s
and
the
authori
z
e
d
ba
ndwi
d
th is un
derutili
zed. T
he LTE (L
ong
Term Evolution, LTE) sy
stem uses MIM
O
(Multiple
Inpu
t Multiple
Out
put)/OF
DM
(Orthog
onal
F
r
equ
en
cy Divi
sion
Multiplex
i
ng)
as the
key
techn
o
logy t
o
effectively
improve
the
quality
of se
rvice of
the 3GPP
(T
he 3rd Gen
e
ration
Partnershi
p
Proje
c
t) syst
em
[1].
And the
u
s
e of
cognitive radi
o (Cog
nitive
Radi
o, CR)
can
effectively improve the
sit
uation of la
ck of
spe
c
tru
m
re
sou
r
ces [2]. Cogniti
ve Radi
o users
(CRUs) dynamically sense spectr
um
holes to access on condition
that they will not affect the
norm
a
l com
m
unication of a
u
thori
z
ed u
s
e
r
s [3].
OFDM te
chn
o
logy ca
n n
o
t only be more flexible
to dynamically allocate
available
spe
c
tru
m
, bu
t also dyna
mically adj
ust modulation,
demod
ulatio
n and e
n
cod
i
ng metho
d
s on
each sub
-
cha
nnel b
a
sed o
n
the fadi
ng
on ea
ch
su
bcarri
er,
whi
c
h
make
s th
e O
F
DM te
chn
o
l
ogy
one of th
e preferred
key t
e
ch
nolo
g
ies for mo
bile
co
mmuni
cation system of
the
next
gene
rat
i
on.
In ord
e
r to
make
the
users’
data
rat
e
high
er, it i
s
p
o
ssible
to
increa
se
th
e u
s
ers’
access
band
width
a
nd al
so
avo
i
d the
wa
st
e of
sca
ttered
spe
c
tru
m
by ad
optin
g the
sp
ect
r
u
m
aggregatio
n (Spectrum Ag
greg
ation, SA) techn
o
l
ogy [4]. Especially
, the DOFDM
(Disco
ntinuo
us
Orthog
onal
Freq
uen
cy Divisio
n
Mul
t
iplexing) te
chn
o
logy in
the SA h
a
s go
od sp
ectral
comp
atibility and it
can
provide g
r
eate
r
band
width
for u
s
e
r
s who
need
hig
h
q
uality of se
rvice
(Quality of Service, QoS
)
.
In view of the
present situa
t
ion of the mob
ile co
mmu
nicatio
n
that the QoS req
u
i
r
eme
n
ts
of multi-user with multi-servic
e
continually increase while t
he radio spe
c
tru
m
resource
s are
seri
ou
sly sca
r
ce
an
d
con
s
ide
r
ing
the
mentione
d
te
chni
cal fa
cto
r
s
above, i
n
this p
ape
r,
we
prop
ose a
ne
w O
F
DM
system mod
e
l b
a
se
d o
n
cog
n
itive radi
o a
nd the
corre
s
pondi
ng
syst
em
frame st
ru
ctu
r
e.
2.
Sy
stem Model and Ass
o
ciated Imple
m
enta
tion
2.1. Sy
stem
Model
Figure 1
sho
w
s th
e p
r
op
ose
d
OF
DM
system
ba
sed on
co
gnit
i
ve radio
cro
s
s-laye
r
model. Th
e model in
co
rp
orate
s
the
sp
ectru
m
ag
gr
e
gation, service division
s a
nd othe
r fact
ors
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
2302-4
046
A Study of Cognitive Tech
nolog
y OF
DM
System
an
d Fram
e St
ru
cture (Hua
Hou)
5515
and can be
more flexible
to adapt to multiservi
ce
m
u
ltiuse
r syste
m
. In this model, the spe
c
trum
hole
s
of the current wirele
ss network en
vir
onme
n
t wa
s se
nsed an
d
judged throu
gh the sp
ectrum
sen
s
in
g te
ch
nology
at first. And the
n
p
a
ss o
n
the
a
v
ailable
sp
ect
r
um i
n
form
ation to t
he
OF
DM
system to all
o
cate
su
bcarri
ers a
nd po
wer
acco
rdin
g to t
he cu
rrent chan
nel
state and t
h
e
spe
c
tru
m
use
status. At last the data stre
am is tran
smi
tted by the OFDM sy
stem.
Figure 1. Pro
posed OF
DM
System Based
on Cogniti
ve Radio
Cro
s
s-laye
r Mod
e
l
The mo
del
con
s
i
s
ts of f
i
ve module
s
,
namely: CR configu
r
ati
on mod
u
le,
servi
c
e
judgme
n
t module, sch
e
d
u
ling alg
o
rith
m module,
sub
c
a
rri
ers module
s
an
d
OFDM syst
em
module. Th
e followin
g
se
cti
ons d
e
scri
be
the basi
c
fun
c
tion
s of these five module
s
:
(1)
CR conf
iguratio
n mo
dule: jud
ge
the cu
rrent
spe
c
tru
m
re
sou
r
ce then
cont
rol
pro
c
e
ssi
ng
b
a
se
d on
the j
udgme
n
t re
sult, so that
cognitive u
s
e
r
s
can
use th
e CR p
e
rcep
tion
res
u
lt rea
s
o
n
ably
.
(2) Servi
c
e
s
judgme
n
t module: acco
rdi
ng to
the existing se
rvice
s
type (name
l
y, voice
servi
c
e
s
, data servi
c
e
s
an
d streami
ng
media serv
ices) a
nd different requi
rem
ent of data rates,
maximum tol
e
rabl
e d
e
lay
and m
a
ximu
m pa
cket e
r
ror
rate
s, etc.
of them, d
o
t
he
sched
ulin
g an
d
allocation for
use
r
re
so
urce
to meet the
QoS req
u
ire
m
ents of diffe
rent users.
With refere
n
c
e to the IE
EE802.1d
standa
rd [5], the u
s
ers’ Q
o
S req
u
ire
m
ents fo
r
different type servi
c
e
s
are sho
w
n in Ta
b
l
e 1.
(3) Scheduli
n
g alg
o
rithm
m
odule: m
u
lti-u
s
er
scheduli
n
g an
d
sub
c
a
r
rier all
o
cation,
ba
sed
on spe
c
ific algorith
m
s a
nd
optimi
z
ati
on
fun
c
ti
on
s, the spe
c
tru
m
inform
atio
n CR m
odul
e
perceived, u
s
er se
rvices in
formation a
n
d
t
he current radio chan
nel
informatio
n st
atus.
(4) Su
bcarrie
r
s a
g
g
r
egati
on mod
u
le: this dia
g
ram
contai
ns t
w
o
different su
bca
rri
er
aggregatio
n module
s
: direct ban
dwi
d
th aggregat
io
n module a
nd multi-carrier agg
re
gati
o
n
module. Th
e former a
pplie
s to contin
uo
us or
small
e
r spa
c
ing
sub
c
arrie
r
s; Th
e latter applie
s
to
the la
rge
r
sp
acin
g
sub
c
a
r
riers [6].
Whi
c
h
mod
e
sh
ould Su
b-ca
rrier ag
gre
gati
on m
odule
u
s
e
depe
nd
s on the cu
rrent scattered de
gre
e
of the sub-
carrie
rs. Th
ere are three case
s: (i) if the
sub
c
a
rri
ers a
llocate
d are
contin
uou
s o
r
small
e
r sp
acin
g, the direct ba
nd
wid
t
h aggre
gatio
n
module
sho
u
l
d be used and the mul
t
i-ca
rrie
r
ag
g
r
egatio
n mo
dule shielde
d
; (ii) wh
en
the
subcarri
ers al
located with l
a
rge
i
n
terval
s, the multi-carrier aggr
egat
ion module will be activated
and
the dire
ct
band
width a
ggre
gation m
odule shiel
d
e
d
; (iii) if both
contin
uou
s a
nd large inte
rvals
sub
c
a
rri
ers a
r
e allo
cated,
two m
odul
es
sho
u
ld
be e
n
abled
sim
u
lta
neou
sly. The
dire
ct ba
nd
wi
dth
aggregatio
n module i
s
re
spon
sible fo
r
continuo
us o
r
smalle
r interv
al sub
c
a
rri
ers and the mult
i-
carrie
r agg
re
gation mod
u
l
e
for larg
er in
terval sub
c
a
r
riers.
(5) OF
DM
sy
stem m
odul
e
:
Set the u
s
e
r
nu
mbe
r
K
and th
e
sub
c
arri
er
num
be
r N an
d
sup
p
o
s
e ea
ch use
r
only h
a
s on
e type of service
s
o
r
has ma
ny types of se
rvice
s
. On the transmit
side,
k u
s
ers’ data flow t
a
ke
ch
annel
codi
ng
an
d i
n
terleavin
g separately an
d ch
ange i
n
to K
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 23
02-4
046
TELKOM
NI
KA
Vol. 12, No. 7, July 201
4: 5514 – 55
21
5516
parall
e
l
d
a
ta strea
m
to
be
modulate
d
. Under c
ontrol of
the adapti
v
e
allo
cation
algorith
m
,
the
K
parall
e
l data
strea
m
is
ma
pped to
different su
bcarrie
r
s and
m
odul
ated.
N m
o
d
u
lated
symbo
l
s
are p
r
o
c
e
s
se
d by IFFT to
obtain time d
o
main
si
gnal.
After adding cycle g
uard intervals a
nd
up-
conve
r
ting,
t
he signal
is transmitted. The re
ce
ivin
g si
de of
m
u
ltiuse
r O
F
DM syste
m
h
a
s K
different u
s
ers. Wh
en the
sign
al re
ach
the k-th
u
s
e
r
throug
h the
fading chan
n
e
l, the receiving
side
processing p
r
o
c
ed
ure reverse t
o
the
se
ndi
ng
side.
Th
e receive
r
i
m
pleme
n
t d
o
wn
conve
r
si
on,
remove th
e g
uard
inte
rval
and
then
ca
rry o
n
F
FT.
And un
de
r th
e control of t
h
e
allocation al
gorithm, the
k-th
user
o
n
ly demo
dul
ates
sub
c
a
rri
ers which a
ssi
gne
d to h
i
m,
transfo
rm
the
pa
rallel
data
into serial
dat
a st
ream
flow, and fin
a
lly d
e
-inte
r
leaved
and
de
cod
e
t
o
obtain the u
s
er’s info
rmati
on data.
Table 1. The
Key Performa
nce Pa
ramet
e
rs of
Differe
nt Service
s
Service ty
p
e
appl
ication
Data rates
Dela
y
Information loss (
P
LR)
Conversational voice
4~64kbit/s
<150ms pref
erred;
<400ms limit
<3% PLR
Voice Messaging
4~32kbit/s
<1s play
back;
<2s r
e
cor
d
<3% PLR
Video 16~384
kbit/s
<150ms
prefer
red;
<400ms record
<1% PLR
Streaming
Audio/voice
16~128 kbit/s
16~384 kbit/s
<10s <1%
PLR
Data
10kb~1Mb
<15s prefer
red;
<60s acceptable
0
2.2. Spectru
m Sensing Algorithm
Spectrum se
nsin
g
m
a
inly perceived
sp
ectru
m
h
o
le
s.
Co
gnitive users
a
nalysi
s
a
nd judge
authori
z
e
d
u
s
ers’ tran
smit
ter sign
al to determi
ne whether the a
u
thori
z
ed u
s
ers’ tra
n
smitter in
workin
g cond
ition. If the authori
z
ed
use
r
s’ tran
smitte
r is not in
wo
rking
co
nditio
n
, that is to
say
the spectrum is idle.
The sign
als can be affect
ed
by
multip
ath
fadi
ng
a
nd shad
ows
effects, et
c. in actu
al
cog
n
itive rad
i
o environm
e
n
t. So CR system might
misjudg
e a
nd gene
rate
interfere
n
ce
to
authori
z
e
d
u
s
ers. T
he
co
operative sp
ectru
m
se
n
s
i
ng alg
o
rithm
pro
p
o
s
ed
h
e
re
enh
an
ce
s the
overall pe
rcei
ved perfo
rma
n
ce g
r
eatly b
y
using a
plu
r
ality of spatial differences o
f
users [7].
Spectrum hol
es d
e
tectio
n
is ge
nerally based
o
n
the
results of
sp
ectral
estim
a
tion for
judgin
g
. In th
is p
ape
r, we
divided
sp
e
c
trum
hol
es i
n
to the
white
hole
(can
b
e
fully used
by
cog
n
itive use
r
s), the g
r
ay
hole (ca
n
b
e
sele
ctiv
ely used by cogniti
ve use
r
s) a
n
d
the bla
c
k h
o
le
(occu
p
ied
by authori
z
e
d
u
s
ers
so
ca
n n
o
t be u
s
ed
b
y
cognitive u
s
ers) a
c
cordi
ng to the current
use
status of the spectrum.
For the
current low
spectrum utilization rate,
we adopt the followi
ng
cooperative
spectrum sensing al
gorithm to effectiv
ely improve the spectrum
utilization i
n
the
pape
r.
Firstly, Ju
dg
e the white
hole by com
parin
g pe
rce
p
tive signal
power
spe
c
trum with
setting maxi
mum po
wer
spectrum.
In the cog
n
itive radio
system with ba
ndwi
d
th
B
,the maximum tol
e
rabl
e interfe
r
en
ce
power spe
c
trum wa
s set a
s
ma
x
. There are followin
g
expression.
ma
x
mi
n
s
P
N
SN
R
(1)
ma
x
ma
x
N
B
(2)
Whe
r
e
s
P
repre
s
ent
s tran
smi
ssi
on po
we
r of cognitive radio sy
stem,
max
N
represents
maximum accepta
b
le interferen
ce po
we
r unde
r en
su
ring com
m
uni
cation q
uality in CR
system
.
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
2302-4
046
A Study of Cognitive Tech
nolog
y OF
DM
System
an
d Fram
e St
ru
cture (Hua
Hou)
5517
mi
n
SN
R
repre
s
e
n
ts the syste
m
minimum si
gnal
to noise ratio
.
If user’
s
sen
s
ing
sign
al po
wer
spe
c
tru
m
do
se not excee
d
the maximum
allowa
ble interferen
ce po
wer
spe
c
trum
ma
x
, we c
an
judge
with cu
rre
nt band
wh
ite hole. Then
judge gray
hole und
er the
premi
s
e of no
n-white hole.
The judg
ment
algorithm i
s
expre
s
sed a
s
follows.
(1) With
ban
dwidth
B
, limit
CR user interference si
g
nal power spectrum whi
c
h i
s
greate
r
th
an t
he maxim
u
m
interferen
ce
power
sp
ect
r
um
s
B
, namely, we
de
mand
that the b
and
o
c
c
u
pa
nc
y r
a
te
is
les
s
than the s
e
tting thres
hold
th
. It is expre
s
sed
as follo
ws:
s
th
B
B
(3)
3
th
B
B
(4)
Whe
r
e
B
repre
s
ent
s allo
wed
sen
s
ing n
a
rrow ba
nd
width
.
(2)
As
sum
e
repre
s
e
n
ts th
e
ratio
of CR
u
s
er inte
rfere
n
ce
sig
nal p
o
wer
spe
c
trum
pea
k
and
ma
x
. Order
th
, where
th
repre
s
ents setting thre
shol
d.
(3)
Th
en defi
ne ratio of
the cog
n
itive use
r
’s inte
rfe
r
en
ce
si
gnal
averag
e p
o
wer
and
ma
x
N
as
,
th
,
th
repre
s
ent
s set thresh
old. We
can cal
c
ul
ate power spe
c
trum
ˆ
()
Sf
throug
h WOS
A
(Weighte
d
Overlap
ped S
egment Averaging
)
[8]
, then calcul
ate interferen
ce sig
nal
averag
e po
wer by the following formula.
1
ˆ
()
fB
PS
f
d
f
B
(5)
In non
-white
hole
ban
d, if t
he frequ
en
cy
band
me
ets f
o
rmul
a
(3),
(4
) a
nd
(5
), the
n
it
can
be jud
ged
as gray h
o
le
so
can
be
sel
e
ctive use
by
CR u
s
e
r
s, oth
e
r
wi
se th
e fre
quen
cy ba
nd
is
black hol
e.
2.3. Spectru
m Aggreg
ati
on
Cog
n
itive ra
d
i
o technol
ogy
ha
s g
r
eatly i
m
prov
e
d
spe
c
trum
efficie
n
c
y. In a
c
tual
study,
cognitive radi
o still faces m
any chall
enges, incl
uding the followi
ng aspects:
(1) If CR u
s
e
r
s
sp
ect
r
um
obtaine
d by t
he
spe
c
tru
m
sen
s
in
g is no
t contin
uou
s
(in time
)
or irre
gula
r
(in sp
ace), in
ord
e
r to
avoid wa
ste
of these
scatt
e
red
spe
c
tru
m
and to f
u
rther
improve
sp
ectrum effici
en
cy, how to
ag
greg
ate the
s
e spe
c
trum t
ogethe
r i
s
a
major challen
ge
recogni
ze
d cognitive radi
o
.
(2) O
w
ing
to
multi-u
s
e
r
s
have diffe
ren
t
se
rvice
s
i
n
cog
n
itive sy
stem, ho
w to
con
s
id
er
cog
n
itive use
r
s’
se
rvice
s
with the d
e
te
cted
spe
c
tru
m
hole to
geth
e
r, for in
stan
ce, meeting
user’s
QoS requi
re
ments
as well
as effe
ctively
improving th
e spe
c
trum
ut
ilization
is
an
other i
s
sue
to
be
resolved. Li
m
i
ted to
cu
rre
nt re
se
arch
on
spe
c
tru
m
aggregatio
n t
e
ch
niqu
es,
we take a
si
m
p
ly
spe
c
tru
m
agg
regatio
n tech
nology in this
pape
r.
In this pap
er,
spe
c
trum
ho
les a
r
e divide
d into co
ntinuou
s and di
scontin
uou
s spectrum
by time; by space divide
d
into re
gula
r
a
nd irre
g
u
la
r spectrum. Fo
r
regul
ar
co
ntin
uou
s spe
c
tru
m
,
we
can u
s
e t
he traditio
nal
method of
spectrum
allo
cation, otherwi
se u
s
e
DOF
D
M technol
o
g
y
pro
c
e
ssi
ng fo
r irre
gula
r
no
n-continu
o
u
s
spe
c
tru
m
.
3.
Sy
stem Frame Structur
e
In the contex
t of LTE-A, we h
a
ve p
r
o
posed
a ne
w
model of
O
F
DM system based
o
n
cog
n
itive radi
o in the se
co
nd se
ction. In this
se
ction
,
a new OFDM frame stru
cture b
a
sed
on
cog
n
itive ra
di
o is
pro
p
o
s
e
d
. It is ba
se
d on th
e sy
stem modul
e,
multi-u
s
er’
s
service
s
and t
h
e
possibility of spe
c
tru
m
agg
regatio
n.
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046
TELKOM
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KA
Vol. 12, No. 7, July 201
4: 5514 – 55
21
5518
The fram
e structure is give
n as follo
wing
Figure 2.
Figure 2. The
Frame Stru
ct
ure Di
ag
ram
The frame
structure incl
ud
es 10 differe
nt se
ction
s
which can be d
i
vided into four part
s
:
the leade
r
se
quen
ce, the i
n
formatio
n field (in
c
ludi
ng
sen
s
in
g field, carrie
r ag
gre
gation field, the
servi
c
e type,
the rate field,
length field,
che
c
k and
a
dditional bit
)
, data field, a
nd FCS
(Fra
me
Che
c
k Seque
nce
)
field.
The frame
st
ructu
r
e
is un
der the
pre
m
i
s
e
of 10
24
subcarrier nu
mber,
maxim
u
m multi
-
path d
e
lay for 200
ns an
d th
e fram
e le
ngt
h 5m
s [9]. Th
e ratio
of
dat
a dete
c
tion
transmi
ssion
time
and the sensi
ng time i
s
1/21 accordi
ng t
o
IEEE
802.22.2 standard
[10]
and literature [11]. Each
se
ction fun
c
tion and o
c
cup
i
ed bits are d
e
scrib
ed a
s
followin
g
.
(1) P
r
ea
mble
: 4 OFDM symbols. Its f
unctio
n
is to
achi
eve fra
m
e dete
c
tion
, frame
synchro
n
ization, AGC, freq
uen
cy offset estima
tion a
n
d
cha
nnel e
s
t
i
mation functi
ons, etc. [12].
(2) Sen
s
in
g field: 7 bits. Re
pre
s
ent
the n
u
mbe
r
of all subcarriers.
(3) Spe
c
tru
m
agg
re
gation:
14
bits. It i
s
u
s
e
d
to
re
pre
s
ent
sta
r
i
ng n
u
mbe
r
a
nd final
numbe
r of su
bca
rri
er. Sub
c
arrie
r
s a
r
e 1
024, unifo
rml
y
distributed i
n
the sub
c
arrier numb
e
r 0
on
both
side
s (n
ot incl
udin
g
0
)
, the
su
bcarrier
numb
e
r in
the
ran
ge f
r
om -512
to
5
12, the
sta
r
ting
and sto
ppin
g
sub
c
a
rri
er a
r
e expre
s
sed
with 7bi
t (in
c
l
uding 1
b
it po
sitive and ne
gative bit).
(4) Se
rvice ty
pe field: 2 bits. It is used t
o
re
p
r
e
s
ent u
s
er’
s
servi
c
e
type. It is shown a
s
Table 2.
Table 2. The
Conte
n
t of Service Type Fi
eld
Service ty
p
e
field
Service ty
p
e
00 Null
01 Audio
service
10 Data
service
11
Streaming media
service
(5) Rate field: 4 bits. Modulatio
n mo
de is divide
d into downl
ink and u
p
link data
modulatio
n i
n
LTE-A sy
stem, as sho
w
n in T
able
3. Downlin
k data modul
ation way m
a
inly
contai
ns
QP
SK, 16-QAM
and 6
4
-QAM. Uplin
k d
a
t
a modulatio
n way m
a
inl
y
applie
s
π
/2 s
h
ift
BPSK, QPSK, 8-PSK and 16-QA
M.
Table 3. The
Conte
n
t of Rate Field
Rate field
Modulation
Code ra
t
e
Coding bits
Data bits
1000(uplink) BPSK
1/2
1
1/2
1001(uplink) BPSK
3/4
1
3/4
1010(uplink) QPSK
1/2
2
1
1011(uplink) QPSK
3/4
2
3/2
1100(uplink)
16-QAM
1/2
4
2
1101(uplink)
16-QAM
3/4
4
3
0010(do
wnlink) QPSK
1/2
2
1
0011(do
wnlink) QPSK
3/4
2
3/2
0100(do
wnlink) 16-QAM
1/2
4
2
0101(do
wnlink) 16-QAM
3/4
4
3
0110(do
wnlink) 64-QAM
2/3
6
4
0111(do
wnlink) 64-QAM
3/4
6
9/2
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TELKOM
NIKA
ISSN:
2302-4
046
A Study of Cognitive Tech
nolog
y OF
DM
System
an
d Fram
e St
ru
cture (Hua
Hou)
5519
(6) Le
ngth fie
l
d: 16
bits. It i
s
u
s
e
d
to i
ndi
cate th
e total
numbe
r
of effective bit
s
ca
rried
by
data se
gment
.
(7)
Che
ck fiel
d: 1 bit.
It is u
s
ed to ch
eck
error in data rate segm
ent and length
se
gment
throug
h odd
-even ch
eck.
(8) Addition
al
bits: 4
bits. It
is
used to
en
sure frame
informatio
n field
ca
n o
c
cupy
all valid
bits wh
en vali
d bit in inform
ation field ca
n not be com
p
letely filled by other fields.
(9)
Data fiel
d
:
It is use
d
to
rep
r
e
s
ent th
at the fram
e
can
ca
rry the
numb
e
r of v
a
lid data
bits. The
r
e
are differe
nt da
ta bits fo
r diff
erent
se
rvice
s
(audi
o se
rvice ar
e
32
0 bit
s
, data
services
are 40
k-bits, strea
m
ing me
dia se
rvice
s
a
r
e 20 k-bit
s
).
(10
)
FCS: 4 b
i
ts. It is used to che
c
k wh
ether data i
s
co
rre
ct in the frame.
4. Simulation
Analy
s
is
In this paper, system model and fra
m
e st
ru
cture
are simul
a
ted unde
r m
a
tlab 7.0
simulatio
n
en
vironme
n
t, and export sp
ectrum test re
su
lts.
We a
s
sume
that the numbers of sub
c
arri
ers are 1024, system
band
width is 10MHz,
transmitted p
o
we
r is 0.5
W
, cyclic p
r
efix
length is
2
5
6
, and sym
b
ol rate i
s
25
Mbps i
n
multi
-
user
CR-OF
D
M d
o
w
nlin
k. In the
simulatio
n
, the numb
e
r
of
radio
cha
nnel
is 6 tra
c
ks, th
e larg
est m
u
lti-
path delay i
s
10us, and m
a
ximum
Doppler
shift
i
s
30Hz. Physi
c
al
layer uses QPSK modulati
on
and dem
odul
ation, and LT
E-A system si
mulation is
se
t to single-in
p
u
t single
-
outp
u
t. At
the sa
me
time, s
e
t
B
=39
980.01
Hz,
th
=3
dB
,
th
=
/
th
B
.
Firstly,
multiply
test
the
sp
ectrum
of
the real
stat
e. Since
the
ban
d u
s
e
condition
cha
nge
s ove
r
time, we de
ri
ved a dete
c
tion re
sult
ran
domly and a
part of sub
c
a
rrie
r
ba
nd sta
t
es
are
shown in
Figure 3. In
t
he figu
re, th
e
vertical
axi
s
rep
r
e
s
ent
s th
e sate of
det
ected
fre
que
ncy
band
s: 0
rep
r
ese
n
ts the
freque
ncy b
a
n
d
is
dete
c
ted
as white em
pty
state,0.5 rep
r
e
s
ent
s
g
r
a
y
state and 1
re
pre
s
ent
s bla
c
k state.
Figure 3. The
Detectio
n Re
sult of
a Ran
dom Sub
c
arri
er Freque
ncy
State
Table
4
sh
o
w
s that m
a
tlab exp
o
rt
s a
v
ailable
ban
d
s
p
e
rce
n
tage
in th
e different test
ca
se
s.
Table 4. Sub
c
arrie
r
Spe
c
trum State Detection Statisti
cs
Statue
Ti
me
White hole
Gra
y
hole
Black hole
Available
1 6.25%
57.03%
36.72%
63.28%
2 7.03%
53.91%
39.06%
60.94%
3 6.38%
55.47%
38.15%
61.85%
0
0.
5
1
1.
5
2
2.
5
3
3.
5
4
4.
5
5
-8
0
-7
0
-6
0
-5
0
-4
0
F
r
equenc
y
/
M
H
z
Po
w
e
r
Sp
e
c
t
r
a
l
D
e
n
s
i
t
y
/
d
B
0
0.
5
1
1.
5
2
2.
5
3
3.
5
4
4.
5
5
0
0.
5
1
F
r
equenc
y
/
M
H
z
S
ubc
ar
r
i
e
r
s
t
at
e
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 23
02-4
046
TELKOM
NI
KA
Vol. 12, No. 7, July 201
4: 5514 – 55
21
5520
Figure 3
an
d
Tabl
e 4
sho
w
that
cogniti
ve ra
dio
users
can
o
c
cupy
more th
an
6
0
% of
freque
ncy b
a
nds in a
ce
rta
i
n perio
d in which the g
r
ay
state occu
py more th
a
n
ha
lf of the band
s.
So we ca
n use spe
c
tru
m
s
aggregatio
n tech
niqu
es to
aggregate
so
me of the ban
ds.
Secon
d
ly, in
orde
r to
verify
syste
m
p
e
rfo
r
man
c
e, thi
s
pape
r to
ok si
mulation
and
analysi
s
on the
propo
sed
sy
stem
model
with th
e ne
w f
r
ame
stru
cture u
n
d
e
r th
e
conditi
ons of mi
nimi
zing
bit erro
r rate.
Unde
r different SNR, the
bit e
rror rate
and packet
error rate betwee
n
CR-b
a
s
ed
OFDM
sy
st
e
m
and
S
I
S
O
LTE
-
A
sy
st
e
m
ar
e
comp
a
r
ed
re
sp
ectiv
e
ly. As i
s
sho
w
n i
n
Fig
u
re
4 an
d
Figure 5.
Figure 4. The
Bit Error Rat
e
unde
r Different
Eb/N0
Figure 5. The
Packet Erro
r Rate un
der
Different Eb/
N
0
In Figure
4, the simulati
on re
sult
s show t
hat
with the sam
e
cha
nnel tran
smissio
n
con
d
ition
s
, th
e same m
o
d
u
lation m
ode
and
co
nst
r
ai
nts of
given t
r
an
smi
ssi
on
rate, the BER of
addin
g
CR m
e
ch
ani
sms
are always b
e
l
o
w the
not
joi
ned
CR
me
chani
sms und
er different S
NR.
This
i
ndicate
s
that
the pro
posed syste
m
model c
a
n
meet re
qui
re
ments
of the
bit error
rate
the
use
r
s’
QoS u
nder th
e
con
d
ition of u
s
in
g the ava
ila
bl
e lice
n
sed
sp
ectru
m
ration
ally. And Clo
s
e to
the theoreti
c
a
l
value.
The simul
a
tio
n
results in Figure 5 sho
w
that, with SNR increa
sin
g
, the packet erro
r rate
of the propo
sed system m
odel fr
am
e st
ructu
r
e
will gradually de
clin
e comp
ared with SISO frame
stru
cture of
LTE-A
syste
m
and
the
p
a
cket e
r
ro
r
rate of fra
m
e
stru
ctu
r
e m
eet u
s
er’
s
Q
o
S
requi
rem
ents
in different SNR.
Acco
rdi
ng to
the ab
ove
simulatio
n
re
sult
s, the
propo
sed
syst
em mod
e
l a
nd fram
e
stru
cture a
r
e
sup
e
rio
r
to th
e current
perf
o
rma
n
ce
of L
T
E-A sy
stem
that it ca
n bet
ter me
et u
s
ers’
QoS requi
re
ments. An
d t
he a
dding
sp
ectru
m
sen
s
i
ng a
nd
sp
ect
r
um
agg
reg
a
tion te
chn
o
log
i
es
can imp
r
ove
spe
c
tru
m
utilization to a ce
rtain ex
tent and provid
e users
with great
er ban
dwi
d
th.
5. Conclu
sion
In the co
ntext of LTE-A research b
a
ckg
r
ound,
a ne
w OFDM syste
m
ba
sed on cognitive
radio
cross-l
a
yer model a
n
d
a suitabl
e frame stru
ctu
r
e
are propo
se
d in this pape
r. The pro
p
o
s
ed
cro
s
s-l
a
yer model add
s function
s of servi
c
e
type
judgm
ent, spectrum hole
s
sen
s
in
g
a
n
d
spe
c
tru
m
ag
g
r
egatio
n. Its a
d
vantage
s a
r
e: (1) th
e
syst
em allo
ws
different u
s
e
r
s to have differe
nt
s
e
r
v
ic
es
an
d e
x
p
a
n
d
th
e s
y
s
t
em app
lic
a
t
ion
sco
pe; (2) th
e
fragm
ented
sp
ect
r
um
s
are
aggregate
d
a
nd used toge
ther. A
nd the
system ca
n meet use
r
s’ band
width re
quire
ment
s a
n
d
effectively improve the fre
quen
cy sp
ect
r
um utilizatio
n.
Comp
ared wi
th LTE-A sta
ndard frame
stru
cture,
the frame struct
ure of this pa
per ha
s
followin
g
advantage
s.
(1) Have
co
gnitive fun
c
tion to
se
nsi
n
g current
ba
ndwi
d
th u
s
e
co
ndition
a
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e usi
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range of spectrum hole and improve
the
utilization rate of spectrum
.
1
2
3
4
5
6
7
8
9
10
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10
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10
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1
2
3
4
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6
7
8
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Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
2302-4
046
A Study of Cognitive Tech
nolog
y OF
DM
System
an
d Fram
e St
ru
cture (Hua
Hou)
5521
(2) Fully
con
s
ider th
e differences i
n
rate
of differe
nt service
s
. Ado
p
t
appropri
a
te
codi
ng
rate and tran
smissio
n
rate
to specifi
c
se
rvic
e, so it ca
n better meet
the need
s of use
r
s.
(3) Carrier ag
greg
ation fiel
d of the
fram
e st
ru
cture
in
dicate
s
su
b-carri
ers’ p
o
siti
on
whi
c
h
contai
n information that n
eed
s to be re
ceived in th
e receiver
side.
It can simplif
y the comple
xity
of the receive facility and avoid blind re
ception.
(4) Th
e ch
eck field in the frame st
ru
ctu
r
e en
su
re
s in
formation a
ccura
cy of information
field and
len
g
th field. An
d FCS fiel
d i
s
to e
n
sure
accuracy
of tran
smitted d
a
ta and
imp
r
ove
transmissio
n quality.
Based
on th
is pa
per’
s
study, the sub
c
arrie
r
allo
ca
tion algo
rith
m unde
r in
crea
sing
different services,
sub
-
chann
el allo
cation
algo
rith
ms ba
se
d o
n
sp
ectrum
aggregatio
n
and
spe
c
tral
cha
r
acteri
stics an
alysis al
gorith
m
s, etc. wo
rth to research.
R
e
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W
ang,
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npi
ng
Li,
Ch
ao
shi
Cai. T
w
o
n
o
vel
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alg
o
rithms for
t
u
rbo
co
des
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sed
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ylo
r
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LT
E
s
y
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T
E
LKOMNIKA Indo
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u
r
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ip
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hang
Qin
y
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ang Y
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Qo
S bas
ed r
e
so
urce
all
o
catio
n
for OF
DM-ba
s
ed C
o
g
n
itiv
e
Radi
o Syste
m
s w
i
th mix
ed
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W
i
re
l
e
ss Comm
unic
a
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w
o
r
k
i
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puti
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h
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adi
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ang W
e
i, Z
han
g Z
h
ao
ya
n
g
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ang
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pi
ng. Sp
ec
trum
ag
greg
atio
n: overvi
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an
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all
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n
a
l T
e
leco
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[6]
3GPP T
R
36.814
v0.4.1. F
u
rther
adva
n
c
e
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r
E-
UT
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y
s
ic
al l
a
yer
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e
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t
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S
G RAN,
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ase 9. 2
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9
; 2.
[7]
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ng
qun,
Xu
n Jia
n
tao, F
eng Z
h
i
y
o
ng,
etc..
Parameters optimiz
atio
n for coop
erati
v
e spectru
m
sensi
ng in c
o
g
n
itive ra
dio
net
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o
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ttings for
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s
urin
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n
c
y
r
e
sp
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nctions
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i
t
h
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e
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hted
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hang Gu
o
y
i, Xu J
i
an,
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izati
on
w
i
th se
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g transmissi
on
time alloc
a
tio
n
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po
w
e
r
control
for coop
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i
rel
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ss
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y
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n
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a
dio-OF
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Evaluation Warning : The document was created with Spire.PDF for Python.