基于快速MIMO-OFDM(9)

沈阳航空航天大学电子信息工程学院毕业设计（论文）

figure(2); hold on

semilogy (SNRin,vblast_ber1,'-*') semilogy (SNRin,vblast_ber2,'-+') semilogy (SNRin,vblast_ber3,'-o') grid on;

xlabel('Eb/No in dB'); ylabel('error probability');

%hold off

V-BLAST子程序：

function [Ber0,Ber1,Ber2,Ber3,Ber4] = vblast(SNRindB) Tx_n = 4; Rx_n = 4; index = 2;

frame_length=120000; % SNRindB=0:2:20;

for i=1:length (SNRindB),

SNR(i)=10^(SNRindB(i)/10); a=rand(1,frame_length); for L=1:frame_length if a(L)>.5 a(L)=1; else a(L)=0; end end

a1=modulation(a,index);

a2=reshape(a1,Tx_n,frame_length/index/Tx_n); sigma = 1/sqrt(2*Rx_n*SNR(i)); AWGN_noise

sigma*(randn(Rx_n,frame_length/index/Tx_n)+j*randn(Rx_n,frame_length/index/Tx_n)); dec0 = zeros(4,frame_length/index/Tx_n); dec1 = zeros(frame_length/index , index); dec2 = zeros(frame_length/index , index); dec3 = zeros(frame_length/index , index); dec4 = zeros(frame_length/index , index); for col_idx = 1:frame_length/index/Tx_n

=

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沈阳航空航天大学电子信息工程学院毕业设计（论文）

H=(randn(Rx_n,Tx_n)+j*randn(Rx_n,Tx_n))/sqrt(2); h=H;

r=H*a2(:,col_idx)+AWGN_noise(:,col_idx); G=pinv(H);

G1=inv(H'*H+sigma.^2*eye(Tx_n))*H'; [gk1 p0]=min(sum(abs(G1).^2,2)); [gk k0]=min(sum(abs(G).^2,2)); r_ic = r; % ML

count=0:1:15;

count1=zeros(4,256); a4=zeros(4,256); for n1=1:16 for n2=1:16

d=[-1,1];

c1=de2bi(count(n2),4); c1=d(c1+1);

c2=de2bi(count(n1),4); c2=d(c2+1); c=c1+j*c2;

count1(:,(n1-1)*16+n2)=c.';

a4(:,(n1-1)*16+n2)=r-H*count1(:,(n1-1)*16+n2); end;% n2 end; % n1

[gk k2]=min(sum(abs(a4).^2,1)); dec0(:,col_idx)=count1(:,k2);

% % ZF det_zf = G*r;

dec2((col_idx-1)*Tx_n+[1:Tx_n],:) = reshape(demodulation(det_zf.',index),2,Tx_n).'; % MMSE det_MMSE=G1*r;

dec3((col_idx-1)*Tx_n+[1:Tx_n],:) = reshape(demodulation(det_MMSE.',index),2,Tx_n).';

% SIC1

for m=1:Tx_n k1(m)=k0;

y=G(k1(m),:)*r_ic;

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沈阳航空航天大学电子信息工程学院毕业设计（论文）

dec1((col_idx-1)*Tx_n+k1(m),:) = demodulation(y,index); b=modulation(dec1((col_idx-1)*Tx_n+k1(m),:),index); r_ic = r_ic - b*H(:, k1(m)); H(:, k1(m))=zeros(Rx_n,1); G=pinv(H);

temp = sum(abs(G).^2,2); temp(k1(1:m)) = 1e10; [gk k0]=min(temp);

end; %m %SIC2

for n=1:Tx_n p1(n)=p0;

y1=G1(p1(n),:)*r;

dec4((col_idx-1)*Tx_n+p1(n),:) = demodulation(y1,index); b1=modulation(dec4((col_idx-1)*Tx_n+p1(n),:),index); r = r - b1*h(:, p1(n));

h(:, p1(n))=zeros(Rx_n,1);

G1=inv(h'*h+sigma.^2*eye(Tx_n))*h'; temp1 = sum(abs(G1).^2,2); temp1(p1(1:n)) = 1e10; [gk1 p0]=min(temp1); end; %m end % col_idx

dec0=reshape(dec0,1,frame_length/index); dec0=demodulation(dec0,index); NumErr0 =sum(dec0~=a)

NumErr1 =sum(abs(reshape(dec1.',1,frame_length)~=a)) NumErr2= sum(abs(reshape(dec2.',1,frame_length)~=a)) NumErr3= sum(abs(reshape(dec3.',1,frame_length)~=a)) NumErr4= sum(abs(reshape(dec4.',1,frame_length)~=a)) Ber0(i) = NumErr0/frame_length; Ber1(i) = NumErr1/frame_length; Ber2(i) = NumErr2/frame_length; Ber3(i) = NumErr3/frame_length; Ber4(i) = NumErr4/frame_length; end; % Eb/N0

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沈阳航空航天大学电子信息工程学院毕业设计（论文）

目 录

第1章 绪 论 ................................................................................................................... - 1 - 1.1 研究背景 .............................................................................................................. - 1 - 1.2 研究意义 .............................................................................................................. - 2 - 1.3 研究状况 .............................................................................................................. - 3 - 1.4 本文主要内容与结构 .......................................................................................... - 4 - 第2章 OFDM基本原理 ................................................................................................ - 5 - 2.1 OFDM原理 .......................................................................................................... - 5 - 2.2 OFDM技术优点 .................................................................................................. - 7 - 2.3 OFDM技术缺点 .................................................................................................. - 8 - 2.4 本章小结 .............................................................................................................. - 9 - 第3章 STBC与VBLAST介绍 .................................................................................. - 10 - 3.1 MIMO简介 ........................................................................................................ - 10 - 3.1.1 MIMO的优势 ............................................................................................. - 11 - 3.2 STBC原理 ......................................................................................................... - 13 - 3.2.1 STBC编码 .................................................................................................. - 13 - 3.2.2 STBC解码 .................................................................................................. - 15 - 3.3 VBLAST原理 .................................................................................................... - 16 - 3.3.1 迫零线性算法 ............................................................................................. - 17 - 3.3.2 串行干扰消除 ............................................................................................. - 17 - 3.4 MRC原理 .......................................................................................................... - 20 - 3.5 本章小结 ............................................................................................................ - 20 - 第4章 多天线OFDM系统的性能分析 ..................................................................... - 21 - 4.1 平台介绍 ............................................................................................................ - 21 - 4.1.1 OFDM调制 ................................................................................................ - 21 - 4.1.2 STBC编码 .................................................................................................. - 23 - 4.2 性能分析 ............................................................................................................ - 24 -

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沈阳航空航天大学电子信息工程学院毕业设计（论文）

4.2.1 STBC性能分析 ......................................................................................... - 24 - 4.2.2 VBLAST性能分析 .................................................................................... - 25 - 4.2.3 STBC与VBLAST性能对比 .................................................................... - 26 - 第5章 结论 .................................................................................................................. - 28 - 致 谢 ........................................................................................................................ - 29 - 参考文献 ........................................................................................................................ - 30 - 附录 程序清单 ............................................................................................................ - 32 -

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