16QAM_matlab.rar

% Designed By yandong, ZHANG % email: [email protected] % Peking University function [mymessage,mysignal_base_band]=Receiver2(y_receive,fc,INSERT_TIMES,MES_LEN,SYM_LEN,BETA,PETAL); %-------------------------接收机---------------------------------- %解调 t=0:1/INSERT_TIMES:SYM_LEN-1/INSERT_TIMES; signal_receiveI=2*y_receive.*cos(2*pi*fc*t); signal_receiveQ=-2*y_receive.*sin(2*pi*fc*t); %解调后滤波 [b,a]=butter(2,2/8); %设计巴特沃斯滤波器 signal_receiveI=filtfilt(b,a,signal_receiveI); signal_receiveQ=filtfilt(b,a,signal_receiveQ); % signal_receiveI=signal_receiveI*1.7; % signal_receiveI=signal_receiveI*1.7; %4倍下采样 signal_after_4downsampleI = signal_receiveI(1:4:end); signal_after_4downsampleQ = signal_receiveQ(1:4:end); signal_after_4downsampleI=[signal_after_4downsampleI(5:end),0,0,0,0]; signal_after_4downsampleQ=[signal_after_4downsampleQ(5:end),0,0,0,0]; signal_after_4downsampleI=1.85*signal_after_4downsampleI;%幅度补偿 signal_after_4downsampleQ=1.85*signal_after_4downsampleQ; figure; subplot(2,1,1) stem([1:20*INSERT_TIMES],signal_after_4downsampleI(1:20*INSERT_TIMES),'.r'); title('接收机4倍下采样后的同相分量'); grid on; subplot(2,1,2) stem([1:20*INSERT_TIMES],signal_after_4downsampleQ(1:20*INSERT_TIMES),'.r'); title('接收机4倍下采样后的正交分量'); grid on; %匹配滤波 signal_after_filterI = rcosflt(signal_after_4downsampleI,1,2,'fir/fs/sqrt',BETA,PETAL+1)'; signal_after_filterQ = rcosflt(signal_after_4downsampleQ,1,2,'fir/fs/sqrt',BETA,PETAL+1)'; signal_after_filterI = signal_after_filterI(2*(PETAL+1)+1:end-2*(PETAL+1)); signal_after_filterQ = signal_after_filterQ(2*(PETAL+1)+1:end-2*(PETAL+1)); figure; subplot(2,1,1) stem([1:20*INSERT_TIMES],signal_after_filterI(1:20*INSERT_TIMES),'.r'); title('接收机匹配滤波后的同相分量'); grid on; subplot(2,1,2); stem([1:20*INSERT_TIMES],signal_after_filterQ(1:20*INSERT_TIMES),'.r'); title('接收机匹配滤波后的正交分量'); grid on; %2倍下采样 signal_after_downsampleI = signal_after_filterI(1:2:end); signal_after_downsampleQ = signal_after_filterQ(1:2:end); figure; subplot(2,1,1) stem([1:20*INSERT_TIMES],signal_after_downsampleI(1:20*INSERT_TIMES),'.r'); title('接收机2倍下采样后的同相分量'); grid on; subplot(2,1,2) stem([1:20*INSERT_TIMES],signal_after_downsampleQ(1:20*INSERT_TIMES),'.r'); title('接收机2倍下采样后的正交分量'); grid on; %星座图 figure; plot(signal_after_downsampleI, signal_after_downsampleQ,'r+'); axis([-2 2 -2 2]); xlabel('I路'); ylabel('Q路'); title('接收机解调信号星座图'); axis([-5,5,-5,5]); grid on; %符号判决 mysignal_base_bandI=zeros(1,SYM_LEN); mysignal_base_bandQ=zeros(1,SYM_LEN); for i=1:1:SYM_LEN if signal_after_downsampleI(i)>=2 mysignal_base_bandI(i)=3; elseif signal_after_downsampleI(i)>=0 mysignal_base_bandI(i)=1; elseif signal_after_downsampleI(i)>=-2 mysignal_base_bandI(i)=-1; else mysignal_base_bandI(i)=-3; end; if signal_after_downsampleQ(i)>=2 mysignal_base_bandQ(i)=3; elseif signal_after_downsampleQ(i)>=0 mysignal_base_bandQ(i)=1; elseif signal_after_downsampleQ(i)>=-2 mysignal_base_bandQ(i)=-1; else mysignal_base_bandQ(i)=-3; end; end; mysignal_base_band=zeros(1,SYM_LEN); mysignal_base_band=mysignal_base_bandI+mysignal_base_bandQ*j; %符号到比特变换 mymessage=zeros(1,MES_LEN); for i=1:1:SYM_LEN tempS=[mysignal_base_bandI(i),mysignal_base_bandQ(i)]; tempB=zeros(1,4); if tempS== [-3,-3] tempB=[1,1,0,0]; elseif tempS== [-3,-1] tempB=[1,1,0,1]; elseif tempS== [-3, 1] tempB=[1,0,0,1]; elseif tempS== [-3, 3] tempB=[1,0,0,0]; elseif tempS== [-1,-3] tempB=[1,1,1,0]; elseif tempS== [-1,-1] tempB=[1,1,1,1]; elseif tempS== [-1, 1] tempB=[1,0,1,1]; elseif tempS== [-1, 3] tempB=[1,0,1,0]; elseif tempS== [ 1,-3] tempB=[0,1,1,0]; elseif tempS== [ 1,-1] tempB=[0,1,1,1]; elseif tempS== [ 1, 1] tempB=[0,0,1,1]; elseif tempS== [ 1, 3] tempB=[0,0,1,0]; elseif tempS== [ 3,-3] tempB=[0,1,0,0]; elseif tempS== [ 3,-1] tempB=[0,1,0,1]; elseif tempS== [ 3, 1] tempB=[0,0,0,1]; elseif tempS== [ 3, 3] tempB=[0,0,0,0]; else null; end; mymessage((i-1)*4+1:i*4)=tempB; end;