pi/4 QDPSK 仿真

%-----------------------------pi/4-QDPSK---------------------------------- clear all; close all; clc; %-------------------------------------------------------------------------- %参数设置 Fc = 5e6; data_len=10000; %-------------------------------------------------------------------------- %随机产生传输信号 rand_data_len =randn(1,data_len); for i=1:data_len if rand_data_len(i)>=0.5 input(i)=1; else input(i)=0; end end %-------------------------------------------------------------------------- %串并转换 for i=1:data_len if rem(i,2)==1 if input(i)==1 I(i)=-1; I(i+1)=-1; else I(i)=1; I(i+1)=1; end else if input(i)==1 Q(i-1)=-1; Q(i)=-1; else Q(i-1)=1; Q(i)=1; end end end %-------------------------------------------------------------------------- % 码变换 I_diff=zeros(1,data_len); Q_diff=zeros(1,data_len); I_diff(1)=I(1); Q_diff(1)=Q(1); for i=2:data_len if I(i)==1&&Q(i)==1 % 0->+1 1->-1 if I_diff(i-1)==1&&Q_diff(i-1)==1 I_diff(i)=1; Q_diff(i)=1; elseif I_diff(i-1)==-1&&Q_diff(i-1)==1 I_diff(i)=-1; Q_diff(i)=1; elseif I_diff(i-1)==-1&&Q_diff(i-1)==-1 I_diff(i)=-1; Q_diff(i)=-1; else I_diff(i)=1; Q_diff(i)=-1; end elseif I(i)==-1&&Q(i)==1 if I_diff(i-1)==1&&Q_diff(i-1)==1 I_diff(i)=-1; Q_diff(i)=1; elseif I_diff(i-1)==-1&&Q_diff(i-1)==1 I_diff(i)=-1; Q_diff(i)=-1; elseif I_diff(i-1)==-1&&Q_diff(i-1)==-1 I_diff(i)=1; Q_diff(i)=-1; else I_diff(i)=1; Q_diff(i)=1; end elseif I(i)==-1&&Q(i)==-1 if I_diff(i-1)==1&&Q_diff(i-1)==1 I_diff(i)=-1; Q_diff(i)=-1; elseif I_diff(i-1)==-1&&Q_diff(i-1)==1 I_diff(i)=1; Q_diff(i)=-1; elseif I_diff(i-1)==-1&&Q_diff(i-1)==-1 I_diff(i)=1; Q_diff(i)=1; else I_diff(i)=-1; Q_diff(i)=1; end else if I_diff(i-1)==1&&Q_diff(i-1)==1 I_diff(i)=1; Q_diff(i)=-1; elseif I_diff(i-1)==-1&&Q_diff(i-1)==1 I_diff(i)=1; Q_diff(i)=1; elseif I_diff(i-1)==-1&&Q_diff(i-1)==-1 I_diff(i)=-1; Q_diff(i)=1; else I_diff(i)=-1; Q_diff(i)=-1; end end end %-------------------------------------------------------------------------- %零内插 zero=5; % 采样率为25MHz for i=1:zero*data_len if rem(i,zero)==1 Izero(i)=I_diff(fix((i-1)/zero)+1); Qzero(i)=Q_diff(fix((i-1)/zero)+1); else Izero(i)=0; Qzero(i)=0; end end %-------------------------------------------------------------------------- %脉冲成形滤波器 NT =50; N=2*zero*NT; Fs=25e6; rf=0.1; psf=rcosfir(rf,NT,zero,Fs,'sqrt'); Ipulse= conv(Izero,psf); Qpulse= conv(Qzero,psf); %-------------------------------------------------------------------------- %调制 for i=1:zero*data_len+N t(i)=(i-1)/(Fc*zero); Imod(i)=Ipulse(i).*sqrt(2)*cos(2*pi*Fc*t(i)); Qmod(i)=Qpulse(i).*(-sqrt(2)*sin(2*pi*Fc*t(i))); end sum=Imod+Qmod; %-------------------------------------------------------------------------- %加噪声 for SNR=0:10 sum1 = awgn(sum,SNR); %-------------------------------------------------------------------------- %解调 %-------------------------------------------------------------------------- %相乘器 for i=1:zero*data_len+N Idem(i)=sum1(i).*sqrt(2)*cos(2*pi*Fc*t(i)); Qdem(i)=sum1(i).*(-sqrt(2)*sin(2*pi*Fc*t(i))); end %-------------------------------------------------------------------------- %匹配滤波器 mtf= rcosfir(rf,NT, zero,Fs,'sqrt'); Imat = conv(Idem,mtf); Qmat = conv(Qdem,mtf); %-------------------------------------------------------------------------- %抽取 for i=1:zero*data_len Isel(i)=Imat(i+N); Qsel(i)=Qmat(i+N); end %-------------------------------------------------------------------------- %采样 for i = 1:data_len Isam(i)= Isel((i-1)*zero+1); Qsam(i)= Qsel((i-1)*zero+1); end %-------------------------------------------------------------------------- %判决 threshold = 0.2; for i = 1:data_len if Isam(i)>= threshold I_final(i)= 0; else I_final(i)= 1; end if Qsam(i) >= threshold Q_final(i) = 0; else Q_final(i)= 1; end end %-------------------------------------------------------------------------- % 码反变换 I_abs=zeros(1,data_len); Q_abs=zeros(1,data_len); I_abs(1)=I_final(1); Q_abs(1)=Q_final(1); for i=2:data_len if I_final(i-1)==0&&Q_final(i-1)==0 %前一输入双比特为00 if I_final(i)==0&&Q_final(i)==0 %本时刻输入00 I_abs(i)=0; Q_abs(i)=0; %输出数据00 elseif I_final(i)==0&&Q_final(i)==1 %本时刻输入01 I_abs(i)=0; Q_abs(i)=1; %输出数据01 elseif I_final(i)==1&&Q_final(i)==1 %本时刻输入11 I_abs(i)=1; Q_abs(i)=1; %输出数据11 else %本时刻输入10 I_abs(i)=1; Q_abs(i)=0; %输出数据10 end elseif I_final(i-1)==0&&Q_final(i-1)==1 %前一输入双比特为01 if I_final(i)==0&&Q_final(i)==0 %本时刻输入00 I_abs(i)=1; Q_abs(i)=0; %输出数据10 elseif I_final(i)==0&&Q_final(i)==1 %本时刻输入01 I_abs(i)=0; Q_abs(i)=0; %输出数据00 elseif I_final(i)==1&&Q_final(i)==1 %本时刻输入11 I_abs(i)=0; Q_abs(i)=1; %输出数据01 else %本时刻输入10 I_abs(i)=1; Q_abs(i)=1; %输出数据11 end elseif I_final(i-1)==1&&Q_final(i-1)==1 %前一输入双比特为11 if I_final(i)==0&&Q_final(i)==0 %本时刻输入00 I_abs(i)=1; Q_abs(i)=1; %输出数据11 elseif I_final(i)==0&&Q_final(i)==1 %本时刻输入01 I_abs(i)=1; Q_abs(i)=0; %输出数据10 elseif I_final(i)==1&&Q_final(i)==1 %本时刻输入11 I_abs(i)=0; Q_abs(i)=0; %输出数据00 else %本时刻输入10 I_abs(i)=0; Q_abs(i)=1; %输出数据01 end else %前一输入双比特为10 if I_final(i)==0&&Q_final(i)==0 %本时刻输入00 I_abs(i)=0; Q_abs(i)=1; %输出数据01 elseif I_final(i)==0&&Q_final(i)==1 %本时刻输入01 I_abs(i)=1; Q_abs(i)=1; %输出数据11 elseif I_final(i)==1&&Q_final(i)==1 %本时刻输入11 I_abs(i)=1; Q_abs(i)=0; %输出数据10 else %本时刻输入10 I_abs(i)=0; Q_abs(i)=0; %输出数据00 end end end %-------------------------------------------------------------------------- %并串转换 for i = 1:data_len if rem(i, 2)== 1 if I_abs(i)== 1 final(i)=1; else final(i)=0; end else if Q_abs(i) == 1 final(i)=1; else final(i)=0; end end end %-------------------------------------------------------------------------- %计算误码率 [num,ber(SNR+1)] = symerr(final,input); end semi