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KHOA VIN THNG 1HI THO TI KHCN CP HC VIN TI:M S TI:
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Mc chMc tiu:Xy dng chng trnh m phng knh MIMO, chng trnh m phng
tch tn hiu trong h thng MIMO-V-BLAST, phc v cng tc nghin cu khoa hc
v o to ca Hc vin.Ni dung:Tng quan h thng MIMO: M hnh h thng v phn
loiM hnh knh MIMO.Nghin cu MIMO-V-BLAST kt hp vi my thu a ngi
dng.Nghin cu cc gii thut tch tn hiu trong h thng MIMOGii thut:
V-BLAST/ZFGii thut: V-BLAST/LLSEGii thut: V-BLAST/ZF/MAP.Gii thut:
V-BLAST/LLSE/MAP.Xy dng chng trnh m phng knh MIMO, v tch sng
MIMO-V-BLAST gm: V-BLAST/ZF; V-BLAST/LLSE; V-BLAST/ZF/MAP;
V-LAST/LLSE/MAP.Kin ngh ng dng chng trnh m phng vo nghin cu khoa hc
& o to Hc vin.Kt qu:Ti liu khoa hc; M hnh h thng-Gii thut-Chng
trnh m phng trn a CD; Bi bo khoa hc c ng trn tp ch hoc hi ngh khoa
hc.
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NI DUNG
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S tng qut knh MIMOc tnh knh v tuyn v m hnh knh MIMO
Ngun pht
Ngun thu
iu ch v m ha
Gii iu ch v gii m
1
n
1
n
t
r
h
11
h
1n
r
h
n
t
1
h
n n
t
r
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Cc hm knh MIMOp ng xung kim knh SISOp ng xung kim knh MIMOc tnh
knh v tuyn v m hnh knh MIMO
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M hnh knh MIMO SVD
Tx1
Tx2
Txm
Rx1
Rx2
Rxn
Y1(k)
Y2(k)
Yn(k)
Xm(k)
X2(k)
X1(k)
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M hnh knh MIMO SVD
Ngun pht
Ngun thu
S/P
P/S
V
UH
H
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SVD (Singular Value Decomposition) ca ma trn knh HTrong U v V l
cc ma trn nht phn, h l chuyn v Hermitian v M hnh knh MIMO SVD
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U.UH = UH.U = IV.VH = VH.V = IN = min(nr,nt)M hnh knh MIMO
SVD
V
VH
U
UH
Knh MIMO
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M hnh my phtM hnh knh MIMO SVD
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M hnh knh MIMO SVDM hnh tp m v nhiu
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M hnh my thuM hnh knh MIMO SVD
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M hnh knh MIMO SVDM hnh my thu
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tng ch o l chn ui mt cch thch ng gim thiu li trung bnh qun phng
MSE
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Trng hp 1: C nhiu v tp m l mt chui cc vector ngu nhin Gaussian
iid
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Dng cc chuyn i kh o V v U chuyn h thng thnh nhiu knh AWGN song
songDung lng di K hn ch cng sut trung bnh
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Trng hp 2: Rww khng phi l bi ca ma trn n v Nghim cho ma trn nh
dng my thu
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Chin lc pht cn ti u n gin
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Gii thut LMS: Thc hin qu trnh lp
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Bt u
Xc nh v nhp cc thng ss anten pht: mS anten thu: nS k hiu uc m
phng: NTn s Doppler:fDThi gian m phng:TSim
nh dng ma trn knhH = Zeros(m,n,N)
k1 < m
k2 < n
Kt qu
Sai
Sai
ng
ng
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k < N
Hr = H(:,1:r,k);Ryy = (P/r)*Hr*Hr' + Rww;Ryx = (P/r)*Hr;U_MSE =
Ryy\Ryx;H_new= sqrt(P/r)*HrHI_new= sqrt(I/K)*H_I(:,:,k)
Hin th ht qu
Rww = (I/K)*H_I(:,:,k)*H_I(:,:,k)' + sigma2*eye(n); H_p=
chol(Rww)'\H(:,:,k);
mu= 0.1;x = sqrt(P/r/2)*(randn(r,1) + i*randn(r,1));x_I=
sqrt(I/K/2)*(randn(K,1) + i*randn(K,1));z =
sqrt(sigma2/2)*(randn(n,1) + i*randn(n,1));y = Hr*x +
H_I(:,:,k)*x_I + z;U= U + 2*mu/(0.1*mu + norm(y)^2)*y*(x -
U'*y)';H_new= sqrt(P/r)*Hr;HI_New=sqrt(I/K)*H_I(:,:,k)
Kt thc
Sai
ng
n = Size(H,1)m = Size(H,2)N = Size(H,3)K = Size(H_I,3)r =
min(m,n)
U = Zeros(N,r)C_op = Zeros(N,1)C_LMS = Zeros(N,1)C_MSE =
Zeros(N,1)
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Bm nghim MMSEKhi chin lc pht n gin kt hp vi nh dng my thu MMSE
cho ta hiu nng gn vi hiu nng ti u nu bm nghim MMSE. V vy, cn phi
kim tra kh nng bm ca cc gii thut thch ng khi nghim thay i theo thi
gian di dng dung lng knh.M phng cho trng hp:1. Ma trn li knh H thay
i do phainh.2. Ma trn li nhiu HI thay i do phainh.
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Trng hp 1: Cc thc th ca H l cc qu trinh phainh Rayleigh c lp vi
li trung binh n v v tn s Doppler fD = 40 Hz. Khng c ngun nhiu ngoi
(HI=0).Tp m my thu c phng sai l Cng sut pht tngTn s ly mu l
2048Hz.
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Kt qu m phng khi m=2 v n=4:Hiu nng bm ca gii thut LMS l km
hn
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L do: Tc hi t ca gii thut LMS ph thuc trc tip vo s lng iu kin ca
ma trn tng quanKhi m=2 v n=2 thi thnh phnc hng y l 2 v c s iu kin
va phi. Vi vy, tnh hi t ca gii thut LMS tng i nhanh
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Khi m=2 v n=4 thi thnh phnC s lch ln gia cc gi tr ring trong Ryy
dn n nhiu iu kin hn v hiu nng bm chm hn.Tng s anten thu th nghim
MMSE tr nn thay i theo thi gian hn v nhy cm vi cc thay i trong knh
hn.
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Trng hp 2: H l ngu nhin nhng c c nh trong mi m phng.HIl qu trnh
phainh Rayleigh c lp c cc li n v trung bnh v tn s Doppler fD:40
Hz.S ngun nhiu: K=2 S anten pht:m=2 S anten thu:n=4Cng sut pht tng
l: 1Cng sut ca mi ngun nhiu l:1/2Phng sai tp m ti mi anten thu
l:0,02
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Kt lun
