w4_zj_2.rar_等增益合并

% This program is reprogramed and tested by Zhang Jing, Shanghai Normal University, % simulates the bit-error-rate (BER) performance of OSTBC,encoding rate 1/2 % with L=4 transmit antennas and R =2 receiver antenna with equal gain combination over the frequency flat Rayleigh block fading channel % modulation- 16 QAM with gray coding resulting in 2 bits/sec/H % this program is reference to the OSTBC program by Samat Shabdanov, February 2007 clc %16 QAM constellation x=[-3 -3 -3 -3 -1 -1 -1 -1 3 3 3 3 1 1 1 1 ]; y=[3 1 -3 -1 3 1 -3 -1 3 1 -3 -1 3 1 -3 -1 ]; Qam=x+y*i; Es=5; %average constellation energy for d=2; index=1; %set SNR step step=3; % SNR range is here for SNR=0:step:21 %number of bit errors set to zero count=0; %number of iterations N=10^4; if SNR==20 N=3*10^4; end; % increase for higher SNR for it=1:N %generate 16 bits uniformly distributed A=round(rand(1,16)); % TX symbols s1=Qam(bi2de(A(1:4),'left-msb')+1); s2=Qam(bi2de(A(5:8),'left-msb')+1); s3=Qam(bi2de(A(9:12),'left-msb')+1); s4=Qam(bi2de(A(13:16),'left-msb')+1); C1=[s1 s2 s3 s4; -s2 s1 -s4 s3; -s3 s4 s1 -s2; -s4 -s3 s2 s1]; C=[C1; conj(C1)]; %Channel coefficients Z=0; K1=1/sqrt(2)*(randn(4,1)+i*randn(4,1)); % normalize to the variance 1 CN(0,1) K2=1/sqrt(2)*(randn(4,1)+i*randn(4,1)); % normalize to the variance 1 CN(0,1) %AWGN channel N0=(4*Es/10^(SNR/10)); Z1=sqrt(N0/2)*(randn(8,1)+i*randn(8,1)); % variance N0 Z2=sqrt(N0/2)*(randn(8,1)+i*randn(8,1)); % variance N0 %RX symbols R1=C*K1+Z1; R2=C*K2+Z2; %decoding ML OSTBC H1=[K1(1) K1(2) K1(3) K1(4); K1(2) -K1(1) K1(4) -K1(3); K1(3) -K1(4) -K1(1) K1(2); K1(4) K1(3) -K1(2) -K1(1)]; H2=[K2(1) K2(2) K2(3) K2(4); K2(2) -K2(1) K2(4) -K2(3); K2(3) -K2(4) -K2(1) K2(2); K2(4) K2(3) -K2(2) -K2(1)]; H1_1=[H1;conj(H1)]; H2_1=[H2;conj(H2)]; R1_1=[R1(1:4); conj(R1(5:8))]; R2_1=[R2(1:4); conj(R2(5:8))]; S1= H1_1'*R1_1/(2*sum(abs(K1).^2)); S2 = H2_1'*R2_1/(2*sum(abs(K2).^2)); S = 0.5*S1+0.5*S2; %symbol decoding for 16-QAM L=[abs(Qam-S(1)); abs(Qam-S(2)); abs(Qam-S(3)); abs(Qam-S(4))]; [D,I]=min(L,[],2); %TX bits dec_bits(1,1:4)=de2bi(I(1)-1,4,'left-msb'); dec_bits(1,5:8)=de2bi(I(2)-1,4,'left-msb'); dec_bits(1,9:12)=de2bi(I(3)-1,4,'left-msb'); dec_bits(1,13:16)=de2bi(I(4)-1,4,'left-msb'); %count errors count=count+sum(abs(A-dec_bits)); end; B_err(index)=count/(N*16) index=index+1; end; semilogy(0:step:21, B_err); hold on;