QPSK.rar_qpsk matlab

clear all; clc; IFFT_bin_length=64;%FFT变换的点数 symbols_per_carrier=2048;%每路载波上的符号数 bits_per_symbol=2; GI=8;%保护间隔的大小 N_snr=60; snr=2; N_number=IFFT_bin_length*symbols_per_carrier*bits_per_symbol; %----------------------------------- %QPSK调制 X=zeros(1,N_number); X=randint(1,N_number); s=(X.*2-1)/sqrt(2); sreal=s(1:2:N_number); simage=s(2:2:N_number); X1=sreal+j.*simage; %------------------------------------ %串并转换 X2=reshape(X1,IFFT_bin_length,symbols_per_carrier); %------------------------------------ %IFFT X3=ifft(X2); %------------------------------------ %加保护间隔 for k=1:symbols_per_carrier; for i=1:IFFT_bin_length; X4(i+GI,k)=X3(i,k); end for i=1:GI; X4(i,k)=X3(i+IFFT_bin_length-GI,k); end end %------------------------------------ %并串转换 X5=reshape(X4,1,symbols_per_carrier*(IFFT_bin_length+GI)); %------------------------------------ %多径干扰 % r=8; % a=[0.09 0.1 0.09 0.082 0.11 0.091 0.1 0.12]; %多径的幅度 % d=[4 5 7 8 9 10 11 12]; % channel1=[zeros(1,d(1)),a(1)*X5(1:length(X5)-d(1))]; % channel2=[zeros(1,d(2)),a(2)*X5(1:length(X5)-d(2))]; % channel3=[zeros(1,d(3)),a(3)*X5(1:length(X5)-d(3))]; % channel4=[zeros(1,d(4)),a(4)*X5(1:length(X5)-d(4))]; % channel5=[zeros(1,d(5)),a(5)*X5(1:length(X5)-d(5))]; % channel6=[zeros(1,d(6)),a(6)*X5(1:length(X5)-d(6))]; % channel7=[zeros(1,d(7)),a(7)*X5(1:length(X5)-d(7))]; % channel8=[zeros(1,d(8)),a(8)*X5(1:length(X5)-d(8))]; % X6=X5+channel1+channel2+channel3+channel4+channel5+channel6+channel7+channel8; X6=X5; %------------------------------------ %加高斯白噪声 Error_ber=[]; %误比特率 for snr_db=0:snr:N_snr code_power=0; code_power=[norm(X5)]^2/(length(X5));%信号的符号功率 bit_power=code_power/bits_per_symbol;%比特功率 noise_power=10*log10((bit_power/(10^(snr_db/10))));%噪声功率 noise=wgn(1,length(X5),noise_power,'complex');%产生GAUSS白噪声信号 Tx_data=X6+noise; %----------------------------------- Y5=Tx_data; %----------------------------------- %串并变换 Y4=reshape(Y5,IFFT_bin_length+GI,symbols_per_carrier); %------------------------------------ %去保护间隔 for k=1:symbols_per_carrier; for i=1:IFFT_bin_length; Y3(i,k)=Y4(i+GI,k); end end Y2=fft(Y3); %---------------------------------- %并串转换 Y1=reshape(Y2,1,IFFT_bin_length*symbols_per_carrier); %---------------------------------- %QPSK解调 y_real=sign(real(Y1)); y_image=sign(imag(Y1)); y_re=y_real./sqrt(2); y_im=y_image./sqrt(2); Rx=[y_re;y_im]; Y=reshape(Rx,1,N_number); %------------------------------------ % dif_bit=s-Y; ber_snr=0; for k=1:N_number; if dif_bit(k)~=0; ber_snr=ber_snr+1; end end; Error_ber=[Error_ber,ber_snr]; end %------------------------------------ %计算误码率 BER=zeros(1,length(0:snr:N_snr)); BER=Error_ber./N_number; BER1=[]; for snr_db=0:snr:N_snr; BER1=[BER1,(erfc(snr_db/sqrt(2)))/2]; end %------------------------------------ i=0:snr:N_snr; semilogy(i,BER,'-*red','linewidth',2); hold on; axis([min(i) max(i) 0.00000001 1]) %semilogy(i,BER1,'-ob'); grid on; %title('QPSK调制解调');