基带ofdm全系统MATLAB代码实现

function output_frame = demodulation(input_modu, index) % demodulation for IEEE802.11a % Input: input_modu, complex values representing constellation points % index % Output: output_frame, output bit stream (data unit is one bit) % In this version, increase the quatilization levels into 8. % note: Matlab index starts from 1 Q_length=length(input_modu); QAM_input_I = real(input_modu); QAM_input_Q = imag(input_modu); output_frame = zeros(1,length(input_modu)*index); switch index case 1, BPSK_Demodu_I = [0 1]; %f(m)=(m+1)/2 + 1, so I=-1 ---> 1, I=1 ---> 2 idx = find(QAM_input_I>1); QAM_input_I(idx) = 1; idx = find(QAM_input_I<-1); QAM_input_I(idx) = -1; output_frame = BPSK_Demodu_I(round((QAM_input_I+1)/2) + 1); case 2, QPSK_Demodu_IQ = [0 1]; %f(m)=(m+1)/2 + 1, so I=-1 ---> 1, I=1 ---> 2 QAM_input_I = QAM_input_I*sqrt(2); QAM_input_Q = QAM_input_Q*sqrt(2); idx = find(QAM_input_I>1); QAM_input_I(idx) = 1; idx = find(QAM_input_I<-1); QAM_input_I(idx) = -1; idx = find(QAM_input_Q>1); QAM_input_Q(idx) = 1; idx = find(QAM_input_Q<-1); QAM_input_Q(idx) = -1; output_frame(1:2:end) = QPSK_Demodu_IQ(round((QAM_input_I+1)/2) + 1); output_frame(2:2:end) = QPSK_Demodu_IQ(round((QAM_input_Q+1)/2) + 1); case 3, remapping=[0 0 0;0 0 1;0 1 0;0 1 1;1 0 0;1 0 1;1 1 0;1 1 1].'; for i=1:Q_length phase_det=[2<QAM_input_I(i)&0<QAM_input_Q(i) 0<QAM_input_I(i)&QAM_input_I(i)<2&0<QAM_input_Q(i) QAM_input_I(i)<-2&0<QAM_input_Q(i) -2<QAM_input_I(i)&QAM_input_I(i)<0&0<QAM_input_Q(i) QAM_input_I(i)<-2&QAM_input_Q(i)<0 QAM_input_I(i)<0&-2<QAM_input_I(i)&QAM_input_Q(i)<0 2<QAM_input_I(i)&QAM_input_Q(i)<0 0<QAM_input_I(i)&QAM_input_I(i)<2&QAM_input_Q(i)<0] a=find(phase_det); output_frame((1+(i-1)*3):(3+(i-1)*3))=remapping((1+(a-1)*3):(3+(a-1)*3)); end case 4, QAM_16_Demodu_IQ = [0 1 3 2]; %f(m)=(m+3)/2 + 1, so I=-3 ---> 1, I=1 ---> 3 QAM_input_I = QAM_input_I*sqrt(10); QAM_input_Q = QAM_input_Q*sqrt(10); idx = find(QAM_input_I>3); QAM_input_I(idx) = 3; idx = find(QAM_input_I<-3); QAM_input_I(idx) = -3; idx = find(QAM_input_Q>3); QAM_input_Q(idx) = 3; idx = find(QAM_input_Q<-3); QAM_input_Q(idx) = -3; tmp = round((QAM_input_I+3)/2) + 1; output_frame(1:4:end) = bitget(QAM_16_Demodu_IQ(tmp),2); output_frame(2:4:end) = bitget(QAM_16_Demodu_IQ(tmp),1); tmp = round((QAM_input_Q+3)/2) + 1; output_frame(3:4:end) = bitget(QAM_16_Demodu_IQ(tmp),2); output_frame(4:4:end) = bitget(QAM_16_Demodu_IQ(tmp),1); case 5, remapping=[0 0 0 0 0;0 0 0 0 1;0 0 0 1 0;0 0 0 1 1;0 0 1 0 0;0 0 1 0 1;0 0 1 1 0;0 0 1 1 1; 0 1 0 0 0;0 1 0 0 1;0 1 0 1 0;0 1 0 1 1;0 1 1 0 0;0 1 1 0 1;0 1 1 1 0;0 1 1 1 1; 1 0 0 0 0;1 0 0 0 1;1 0 0 1 0;1 0 0 1 1;1 0 1 0 0;1 0 1 0 1;1 0 1 1 0;1 0 1 1 1; 1 1 0 0 0;1 1 0 0 1;1 1 0 1 0;1 1 0 1 1;1 1 1 0 0;1 1 1 0 1;1 1 1 1 0;1 1 1 1 1].'; for i=1:Q_length phase_det=[4<QAM_input_I(i)&0<QAM_input_Q(i)&QAM_input_Q(i)<2;2<QAM_input_I(i)&QAM_input_I(i)<4&0<QAM_input_Q(i)&QAM_input_Q(i)<2;0<QAM_input_I(i)&QAM_input_I(i)<2&0<QAM_input_Q(i)&QAM_input_Q(i)<2;4<QAM_input_I(i)&2<QAM_input_Q(i)&QAM_input_Q(i)<4; 2<QAM_input_I(i)&QAM_input_I(i)<4&2<QAM_input_Q(i)&QAM_input_Q(i)<4;0<QAM_input_I(i)&QAM_input_I(i)<2&2<QAM_input_Q(i)&QAM_input_Q(i)<4;2<QAM_input_I(i)&QAM_input_I(i)<4&4<QAM_input_Q(i);0<QAM_input_I(i)&QAM_input_I(i)<2&4<QAM_input_Q(i); QAM_input_I(i)<-4&0<QAM_input_Q(i)&QAM_input_Q(i)<2;-4<QAM_input_I(i)&QAM_input_I(i)<-2&0<QAM_input_Q(i)&QAM_input_Q(i)<2;-2<QAM_input_I(i)&QAM_input_I(i)<0&0<QAM_input_Q(i)&QAM_input_Q(i)<2;QAM_input_I(i)<-4&2<QAM_input_Q(i)&QAM_input_Q(i)<4; -4<QAM_input_I(i)&QAM_input_I(i)<-2&2<QAM_input_Q(i)&QAM_input_Q(i)<4;-2<QAM_input_I(i)&QAM_input_I(i)<0&2<QAM_input_Q(i)&QAM_input_Q(i)<4;-4<QAM_input_I(i)&QAM_input_I(i)<-2&4<QAM_input_Q(i);-2<QAM_input_I(i)&QAM_input_I(i)<0&4<QAM_input_Q(i); QAM_input_I(i)<-4&-2<QAM_input_Q(i)&QAM_input_Q(i)<0;-4<QAM_input_I(i)&QAM_input_I(i)<-2&-2<QAM_input_Q(i)&QAM_input_Q(i)<0;-2<QAM_input_I(i)&QAM_input_I(i)<0&0<QAM_input_Q(i)&QAM_input_Q(i)<0;QAM_input_I(i)<-4&-4<QAM_input_Q(i)&QAM_input_Q(i)<-2; -4<QAM_input_I(i)&QAM_input_I(i)<-2&-4<QAM_input_Q(i)&QAM_input_Q(i)<-2;-2<QAM_input_I(i)&QAM_input_I(i)<0&-4<QAM_input_Q(i)&QAM_input_Q(i)<-2;-4<QAM_input_I(i)&QAM_input_I(i)<-2&QAM_input_Q(i)<-4;-2<QAM_input_I(i)&QAM_input_I(i)<0&QAM_input_Q(i)<-4; 4<QAM_input_I(i)&-2<QAM_input_Q(i)&QAM_input_Q(i)<0;2<QAM_input_I(i)&QAM_input_I(i)<4&-2<QAM_input_Q(i)&QAM_input_Q(i)<0;0<QAM_input_I(i)&QAM_input_I(i)<2&0<QAM_input_Q(i)&QAM_input_Q(i)<0;4<QAM_input_I(i)&-4<QAM_input_Q(i)&QAM_input_Q(i)<-2; 2<QAM_input_I(i)&QAM_input_I(i)<4&-4<QAM_input_Q(i)&QAM_input_Q(i)<-2;0<QAM_input_I(i)&QAM_input_I(i)<2&-4<QAM_input_Q(i)&QAM_input_Q(i)<-2;2<QAM_input_I(i)&QAM_input_I(i)<4&QAM_input_Q(i)<-4;0<QAM_input_I(i)&QAM_input_I(i)<2&QAM_input_Q(i)<-4]; a=find(phase_det); output_frame((1+(i-1)*5):(5+(i-1)*5))=remapping((1+(a-1)*5):(5+(a-1)*5)); end %5+i 3+i 1+i 5+3*i 3+3*i 1+3*i 3+5*i 1+5*i -5+i -3+i -1+i -5+3*i -3+3*i -1+3*i -3+5*i -1+5*i -5-i -3-i -1-i -5-3*i -3-3*i -1-3*i -3-5*i -1-5*i 5-i 3-i 1-i 5-3*i 3-3*i 1-3*i 3-5*i 1-5*i case 6, QAM_64_Demodu_IQ = [0 1 3 2 6 7 5 4]; %f(m)=(m+7)/2 + 1, so I=-7 ---> 1, I=1 ---> 5 idx = find(QAM_input_I>7); QAM_input_I(idx) = 7; idx = find(QAM_input_I<-7); QAM_input_I(idx) = -7; idx = find(QAM_input_Q>7); QAM_input_Q(idx) = 7; idx = find(QAM_input_Q<-7); QAM_input_Q(idx) = -7; tmp = round((QAM_input_I+7)/2) + 1; output_frame(1:6:end) = bitget(QAM_64_Demodu_IQ(tmp),3); output_frame(2:6:end) = bitget(QAM_64_Demodu_IQ(tmp),2); output_frame(3:6:end) = bitget(QAM_64_Demodu_IQ(tmp),1); tmp = round((QAM_input_Q+7)/2) + 1; output_frame(4:6:end) = bitget(QAM_64_Demodu_IQ(tmp),3); output_frame(5:6:end) = bitget(QAM_64_Demodu_IQ(tmp),2); output_frame(6:6:end) = bitget(QAM_64_Demodu_IQ(tmp),1); end