Khảo sát ảnh hưởng của dịch tần đến hệ thống MB-OFDM
Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (1.71 MB, 81 trang )
ĐA
̣
I HO
̣
C QUÔ
́
C GIA HA
̀
NÔ
̣
I
TRƯƠ
̀
NG ĐA
̣
I HO
̣
C CÔNG NGHÊ
̣
LƯU VĂN HOAN
KHO ST NH HƯNG CA DCH
TÂ
̀
N ĐÊ
́
N HÊ
̣
THÔ
́
NG MB-OFDM
LUÂ
̣
N VĂN THA
̣
C SI
̃
H Ni - 2011
-OFDM
2011
n:
-OFDM
:
:
: 60 52 70
:
- 2011
iv
i
ii
T iii
iv
vi
viii
ix
x
1:
1.1.
- 1 -
1.1.1.
- 1 -
1.1.2. - 1 -
1.1.3. - 4 -
1.2. - 5 -
1.3. - 5 -
1.4.
- 6 -
2:
-OFDM
2.1.
-OFDM - 7 -
2.1.1.
- 7 -
2.1.2.
- 8 -
2.1.2.1.
- 9 -
2.1.2.2. 10 -
2.2. 12 -
2.3.
14 -
2.4.
-OFDM 17 -
2.4.1. 18 -
2.4.2. 18 -
2.5.
-OFDM
20 -
2.6. -OFDM 24 -
2.6.1. 30 -
2.6.2. 31 -
v
3: -OFDM
3.1.
35 -
3.2.
39 -
3.3. 47 -
3.4. 52 -
4:
4.1.
54 -
4.2.
55 -
4.2.1. 55 -
4.2.2. MIMO Multiband OFDM 55 -
- 56 -
: g MB-OFDM - 58 -
vi
1.1.
. - 2 -
1.2.
. - 2 -
1.3. . - 3 -
1.4. : (a)
(b)
. - 4 -
2.1.
. - 7 -
2.2.
. - 8 -
2.3.
-OFDM. - 9 -
2.4.
-OFDM. - 9 -
2.5.
-OFDM. 11 -
2.6.
-OFDM. 11 -
2.7.
-
. 13 -
2.8.
15 -
2.9.
. 16 -
2.10. G. 19 -
2.11. . 21 -
2.12. 1. 22 -
2.13. 2. 22 -
H2.14. 3. 23 -
2.15. 4. 23 -
2.17.
. 26 -
2.18. = 0.04 % . 27 -
2.19. = 0.5 % . 27 -
2.20. = 1 % . 28 -
2.21. = 0.1%. 28 -
2.22. AWGN khi CFO = 2%. 29 -
2.23. 1 khi CFO = 0.1%. 29 -
2.24.
1 khi CFO = 2%. 30 -
2.25. . 31 -
2.26. = 0.04%. 33 -
2.27. = 0.1%. 33 -
2.28. = 0.5%. 34 -
3.1. CM1 CM4
. 36 -
3.2. . 37 -
vii
3.3. 1
. 37 -
3.4. 2
. 38 -
3.5. 3
. 38 -
3.6. 4
nhau. 39 -
3.7.
-
-368 39 -
3.8.
CP preamble. 40 -
3.9.
3 1. 41 -
3.10.
3 2. 41 -
3.11.
3 3. 42 -
3.12.
3 4. 42 -
3.13.
. 46 -
3.14. = 0.04% 0.5%. 47 -
3.15. = 0.1% 2%. 48 -
3.16. = 0.1%,
(),
(). 48 -
3.17. m sao trên kênh AWGN khi CFO = 2%,
(),
(). 49 -
3.18. 1
= 0.04% 0.5%. 49 -
3.19. 1
= 0.1% 2%. 50 -
3.20. 1 khi CFO = 2%,
(),
().
50 -
3.21. . 51 -
3.22. , CM1, CM2
= 2 %. 51 -
3.23. , CM3, CM4
= 2 %. 52 -
3.24.
SNR = 18 dB. 53 -
viii
2.1. - 8 -
2.2. . 12 -
2.3.
. 14 -
2.4. . 20 -
2.5.
1. 21 -
2.6. . 25 -
ng 3.1. . 39 -
3.2. 1. 40 -
g 3.3.
. 41 -
ix
STT
1
BER
Bit Error Rate
2
CFO
Carrier Frequency Offset
3
CM
Channel Model
Mô h
4
CRLB
Rao Lower Bound
- Rao
5
DSS
Direct-Sequence Spreading
6
ECMA
European Computer Manufactures
Association
7
FFT
Fast Fourier Transform
8
IFFT
Invert Fast Fourier Transform
9
MAC
Multi Access Control layer
10
MB-OFDM
Multiband OFDM
11
MSE
Mean Square Error
12
OFDM
Orthogonal Frequency-Division
Multiplexing
13
PAM
Pulse Amplitude Modulation
14
PHY
Physical layer
15
PLCP
Physical Layer Convergence
Protocol
16
PPM
Pulse Position Modulation
17
PSDU
PHY Service Data Unit
18
TFC
Time-Frequency Code
-
19
UWB
Ultra-Wideband
B
20
WPAN
Wireless Personal Areal Network
21
WUSB
Wireless Universal Serial Bus
x
.
b
(CFO)
b
b
b
arg .
.E
(.)Var
(.,.)f
Re .
Im .
- 1 -
1.1.
g
(UWB)
1960
,
[1].
(Ultra-WideBand)
1989
.
1990,
.
1.1.1.
(FCC) cho UWB.
,
n 500 MHz
B/f
c
> 0.2,
B = f
H
f
L
-10
f
c
=(f
H
+f
L
)/2 ; f
H
f
L
-10 dB
[1].
: 3.1 GHz
10.6
(PSD)
1.1.
,
1 MHz
-41.3 dBm.
1.2,
,
.
1.1.2.
,
cho
.
:
( ),
( )
(
).
(
7.5 GHz),
.
,
.
,
2
- 2 -
:
(
WPAN),
(,
).
,
.
1.1.
[1].
1.2.
[1].
( 5
10
) 100
500 Mbps trong
1.6
1.9
2.4
3.1
5.0
10.6
GPS
PCS
Bluetooth
802.11b
Cordless Phone
Microwave Ovens
802.11a
802.15
(GHz)
- 3 -
20 m.
(WUSB)
(PC) i,
,
(1.3).
(a).
.
(b).
, [22].
H1.3. CWPAN
.
- 4 -
1.1.3.
UWB
, 2 :
(single-band) (multiband) [1]. 1.4
(
) (
).
1.4. : (a)
(b)
[1].
i,
(impulse radio)
.
,
(pico second).
.
.
,
1 bit thông tin.
(PAM)
(PPM).
(time-hopping)
(DSS). ,
.
. Tuy nhiên,
,
thu
.
,
.
,
UWB
3.1
10.6 GHz th
(subband).
500 MHz theo
.
n ,
,
.
- 5 -
,
(MB-OFDM),
(OFDM),
.
.
,
(
).
:
,
. a
. -OFDM s
(frequency synthesizer) (frequency hopping). Khi s
-(TFC)
,
.
MB-OFDM
802.15.3
WPAN
(ECMA) -368.
1.2.
(MB-OFDM). (timing synchronization)
(frequency offset estimation)
-OFDM.
(Frequency Offset - FO)
:
,
(Carrier Frequency Offset - CFO),
(ADC) (Sampling Frequency Offset - SFO).
gây ra ICI.
, nên ta
(BER)
.
(Carier
Frequency Offset CFO)
kênh UWB. ,
3 .
1.3.
(CFO)
. Tuy nhiên, c
,
-
.
, 2
.
,
(Maximum
Likelihood ML) [2].
2 .
.
, trên mi,
[3]
2 (traning
symbol)
.
2
,
CFO.
,
2
CFO.
. N,
,
[13, 14, 15].
- 6 -
-OFDM,
CFO
. Yak [4]
C
[2],
2
(PS) trong
,
.
1 2. Tuy nhiên,
-
CFO. Sahu [5]
MB-
C
3. Li [6]
(Best Linear Unbiased Estimator BLUE)
C
-OFDM. Li
[16].
,
,
10 Hz.
con,
. Trong
[17], Debarati Sen
3
1 -OFDM.
. Debarati Sen [7]
C
[3]
-
trên
.
c so
[17].
1 2.
[17]
:
.
1.4.
. 2
-OFDM
-368,
802.15.3a.
.
.
,
ATLAB
kênh UWB (CM1
CM4)
C
sao. C
.
3 -OFDM.
lu (
)
.
theo,
.
,
. ,
MATLAB .
4
.
- 7 -
-OFDM
2.1.
-OFDM
-368 [10]
(PHY)
(MAC) cho
(WPAN),
3100 10600 MHz,
480 Mbps .
2.1.1.
n ECMA-368, p
14 (subband),
528 MHz
2.1.
, 12
(1
12)
4 (band group),
3 .
2 (13 14) .
9, 10 11 ,
.
1 trong 6 .
, 1 .
2.1.
[10].
f
c
n
b
2.1
. 2.1 .
f
c
(n
b
) = 2904 + 528 x n
b
(MHz),
n
b
(2.1)
#1
#2
#3
#4
#5
#6
#7
#8
#9
#10
#11
#12
#13
#14
#1
#2
#3
#4
#5
#6
3432
MHz
3960
MHz
4488
MHz
5016
MHz
5544
MHz
6072
MHz
6600
MHz
7128
MHz
7656
MHz
8184
MHz
8712
MHz
9240
MHz
9768
MHz
10296
MHz
- 8 -
2.1.
[10].
(n
b
)
(MHz)
(MHz)
(MHz)
1
1
3168
3432
3696
2
3696
3960
4224
3
4224
4488
4752
2
4
4752
5016
5280
5
5280
5544
5808
6
5808
6072
6336
3
7
6336
6600
6864
8
6864
7128
7392
9
7392
7656
7920
4
10
7920
8184
8448
11
8448
8712
8976
12
8976
9240
9504
5
13
9504
9768
10032
14
10032
10296
10560
6
9
7392
7656
7920
10
7920
8184
8448
11
8448
8712
8976
2.1.2.
-
.
-
(TFC) . 2.2
1.
2.2.
[10].
2.3 2.4
-OFDM.
chung, :
.
:
(data scrambler ),
(convolution encoder and
puncturer),
(bit interleaver),
(constellation mapper),
T
ZP
T
SYM
(ns)
3168
3696
4224
4752
#1
#2
D#3
T
FFT
(MHz)
Symbol 1
Symbol 2
Symbol 3
Symbol 4
Symbol 5
Symbol 6
- 9 -
(IFFT).
,
.
2.3.
MB-OFDM.
2.4.
MB-OFDM.
2.1.2.1.
n
(data scrambler).
bit .
bit 0
1.
bit
,
.
,
.
PLCP
header
QPSK/DCM
mang pilot,
,
mang null
& IFFT
/
Song
song
.
.
.
.
.
.
Song
song /
PLCP
preamble
RF
Re{x
l
(n)}
s
RF
(t)
X
l
(0)
X
l
(N
FFT
-1)
x
l
(0)
x
l
(N
FFT
-1)
Im{x
l
(n)}
X
l
(k)
RF
OLA
CP
(FFO)
FO
FFT
kênh,
RFO
kênh,
Viterbi
,
x
l
(n)
- 10 -
(convolution encoder)
(puncturer).
(SNR) . Khi
,
,
,
.
-368
5 : 1/3, 11/32, 1/2, 5/8 3/4.
1/3
. ,
Viterbi (Viterbi decoder)
.
.
bit 0
.
(bit interleaver).
. ênh,
.
,
.
,
.
(constellation
mapper).
.
200
Mbps,
.
320 Mbps,
.
X
l
(n),
n N
FFT
1 l N
packet
- 1.
.
,
(frequency-domain spreading) trong 1 (time-domain
spreading) qua 2
.
122 con
128 ,
100 , 12 hoa tiêu, 10
, 6 0. n
l I
x
l
(n),
n N
FFT
1 l N
packet
- 1.
2.1.2.2.
-OFDM,
3
(TFC)
.
,
. 2.2
1 = [1 2 3 1 2 3].
-368,
1, 2, 3, 4 6 10
; 5 3 TFC.
x
l
(t)
l
x
l
(n)
(DAC)
( ) ( ) ( )
l I Q
x t x t jx t
(2.2)
,
( ) Re{ ( )}
Il
x t x t
( ) Im{ ( )}
Ql
x t x t
x
l
(t).
,
x
l
(t)
(up-convert)
- 11 -
(mixer)
ic,
,
ic,
i = 1, 2, 3 trung tâm
1, 2, 3 3432 MHz, 3960
4488 MHz.
.
T
SYM
= 312.5 ns,
T
ZP
.
(frequency synthesizer) 3
ic,
,
. 2.5 2.6
RF
MB-OFDM.
2.5.
MB-OFDM.
2.6.
MB-OFDM [9].
DAC
DAC
BPF
PA
1,c
2,c
3,c
TFC
Re{ ( )}
l
xt
Im{ ( )}
l
xt
Cos
Sin
Re{ ( )}
l
xn
Im{ ( )}
l
xn
s
RF
(t)
BPF
LNA
LPF
LPF
ADC
ADC
AGC
AGC
1,c
2,c
3,c
Cos
Sin
- 12 -
2.2.
K UWB ,
[8].
,
. ,
,
,
,
. 0.3
1 ns.
7.5 GHz, nên
133
.
n
, 1
m,
.
Saleh-Valenzuela (S-V) (2.7)
802.15.3a v
UWB.
:
,
(LOS).
4
(channel model CM),
CM1, CM2, CM3
CM4,
(LOS) hay
(NLOS) .
1
4 m.
2
1,
. Kênh CM3
4 10 m. Kênh CM4 tron
(25 ns). 2.2 4
.
2.2. .
Kênh
CM1
CM2
CM3
CM4
(m)
0 4
0 4
4 10
10
LOS
NLOS
NLOS
NLOS
802.15.3a [8]
,,
00
( ) ( )
LK
i i i i
i k l l k l
lk
h t X t T
(2.3)
:
- {
i
lk,
} k
l (realization)
i.
- {
i
l
T
} l i.
- {
i
lk,
}
k
trong l.
- {X
i
}
i.
802.15.3
:
- T
l
l.
-
.
-
.
- 13 -
: t = 0,
T
0
= 0,
l
l,0
= 0.
,
Poisson,
.
:
11
exp|
llll
TTTTP
,
l > 0 (2.4)
lkklklk
p
),1(1),1(,
exp|
,
k > 0 (2.5)
2.7.
-V
.
:
lkllklk
p
,,,
(2.6)
),(log20
2
2
2
1,,10
lklkl
hay
20
,
21,
10
nn
lkl
lk
(2.7)
n
1
),0(
2
1
n
2
),0(
2
2
.
lk
l
eeE
T
lkl
,
0
2
,
(2.8)
, T
l
l
0
(),
1
,
lk
p
/
l
T
e
/
,lk
e
1/
1/
T
0
T
1
T
2
T
3
0
1
2
3
- 14 -
( -1).
.
,
lk,
20
)10ln(
)10ln(
1010ln10
2
2
2
1
,
0
,
lk
l
lk
T
(2.9)
,
l
l,
lk,
k
l.
X
i
,
{
i
lk,
}
1
.
L
l
K
k
lk
0 0
2
,
1
(2.)
:
),0()(log20][
2
10 xii
XdBX
(2.10)
802.15.3
2.3.
2.3. [8].
CM1
CM2
CM3
CM4
- t
(ns
-1
)
0.0233
0.4
0.0667
0.0667
- t(ns
-1
)
2.5
0.5
2.1
2.1
- h
7.1
5.5
14.00
24.00
- h
4.3
6.7
7.9
12
1
-
(dB)
3.4
3.4
3.4
3.4
2
-
(dB)
3.4
3.4
3.4
3.4
x
-
X
i
(dB)
3
3
3
3
0
-
1
1
1
1
2.3.
{X
l
(k)}
i .
/
IFFT.
N
FFT
= 128
. n
l
:
1
2 ( )
0
1
( ) ( ) ( )
FFT
FFT
FFT
k
N
j n lN
N
l FFT l
k
FFT
x n x n lN X k e
N
(2.11)
- 15 -
lN
FFT
n < (l + 1)N
FFT
l N
packet
1,
N
packet
.
,
(Cyclic Prefix CP)
ISI do
gây ra. ,
.
. ,
ECMA-368
.
N
ZP
= 37
0, S (zero padding surfix)
(2.8b). Tuy nhiên, khi
S
(Overlap-and-Add),
CP [21].
S
. KN
SYM
= N
FFT
+ N
ZP
. i S :
()
()
0
l ZP
l
x n N
xn
(2.11), :
1
2 ( )
0
1
()
()
0
FFT
SYM ZP
FFT
k
N
j n lN N
N
l
l
k
FFT
X k e
xn
N
(2.12)
2.8
sau khi
S.
(a) T
S.
(b) Sau khi ZPS.
2.8.
.
l-1
N
FFT
ZPS
N
ZP
l
N
FFT
ZPS
N
ZP
l+1
N
FFT
ZPS
N
ZP
lN
SYM
lN
SYM
+ N
FFT
(l - 1)N
SYM
lN
SYM
+N
FFT
+N
ZP
=(l+1)N
SYM
lN
FFT
(l + 1)N
FFT
l-1
N
FFT
Sy
l
N
FFT
l+1
N
FFT
(l - 1)N
FFT
,
lN
SYM
n < lN
SYM
+ N
FFT
,
lN
SYM
+ N
FFT
n < (l + 1)N
SYM
,
lN
SYM
n < lN
SYM
+ N
FFT
,
lN
SYM
+ N
FFT
n < (l + 1)N
SYM
- 16 -
, N
FFT
l
:
1
2 ( )
0
1
( ) ( )
FFT
SYM ZP
FFT
k
N
j n lN N
N
ll
k
FFT
x n X k e
N
,
lN
SYM
n < lN
SYM
+ N
FFT
(2.13)
x
l
(t)
Re{ ( )}
l
xn
Im{ ( )}
l
xn
x
l
(n) trong (2.12) qua
(DAC) 2.9.
2.9.
[10].
1
2 ( )
0
1
()
()
0
FFT
k SYM ZP
N
j f t lT T
l
k
l
FFT
X k e
xt
N
(2.14)
,
f
k
= k/T
FFT
k
.
T
FFT
= 1/D
f
= N
FFT
/f
s
.
f
s
D
f
.
T
ZP
= N
ZP
/f
s
S.
T
SYM
= T
FFT
+ T
ZP
S.
i N
packet
OFDM x
l
(t)
,
2 ( )
c b c
fb
con
b.
p
:
1
0
( ) Re ( )exp( 2 ( ( ))
packet
N
RF l c
l
s t x t j f q l t
(2.15)
, Re[.] , N
packet
, f
c
(m)
m, q(l)
l
, x
l
(t)
l
trong (2.14), : x
l
(t) = 0
t
[0, T
SYM
).
l trong ,
PLCP preamble, PLCP header hay PSDU (
3.1).
DAC
DAC
Re{x
l
(n)}
Re{x
l
(t)}
Im{x
l
(n)}
Im{x
l
(t)}
,
lT
SYM
t < lT
SYM
+T
FFT
,
lT
SYM
+T
FFT
t < (l+1)T
SYM
