信号与系统奥本海姆Matlab simulation of OFDM.docxVIP

Matlab simulation of OFDM 梁锦豪 刘乙樽 张了 Introduction：The full name of OFDM is Orthogonal Frequency Division Multiplexing,which is a method of encoding digital data on multiple carrier frequencies.It has high spectral efficiency and can decease the narrow-band co-channel interference. %1 Creating the example bit sequence（information）at the very beginning, and it’s easy to change it into time domain by IDFT LengthMessage = 8; Information = [1 2 3 4 5 6 7 8]; InformationIFFT = ifft(Information); subplot(2,1,1),stem(Information),xlabel(The input signal) ; subplot(2,1,2),stem(abs(InformationIFFT)),xlabel(Inverse DTF ofThe input signal) %2. Add the CP in the front of the InformationIFFT , we set the length of CP is 2. Change the discrete signal into analogy signal.And chose the proper carry frequency by analyzing its spectral. CPLength =2; TxSignal =[InformationIFFT(end-CPLength+1:end) InformationIFFT]; %加CP后的信号 T=0.001; t=[0.001:0.001:10]; for i=1:(1/T) %把它扩展成连续信号 TxSignalThen1(i)= TxSignal(1); TxSignalThen2(i)= TxSignal(2); TxSignalThen3(i)= TxSignal(3); TxSignalThen4(i)= TxSignal(4); TxSignalThen5(i)= TxSignal(5); TxSignalThen6(i)= TxSignal(6); TxSignalThen7(i)= TxSignal(7); TxSignalThen8(i)= TxSignal(8); TxSignalThen9(i)= TxSignal(9); TxSignalThen10(i)= TxSignal(10); end TxSignalThen=[TxSignalThen1 TxSignalThen2 TxSignalThen3 TxSignalThen4 TxSignalThen5 TxSignalThen6 TxSignalThen7 TxSignalThen8 TxSignalThen9 TxSignalThen10]; subplot(2,1,1),plot(t,abs(TxSignalThen)),xlabel(time domain) TxSignalThenfreq=fftshift(T*fft(TxSignalThen)); %傅立叶变换成频域观察 w1=-(pi/T)+(0:9999)*(2*pi/(10000*T)) subplot(2,1,2),plot(w1,abs(TxSignalThenfreq)),xlim([-300 300]),xlabel(frequency domain) % chose the proper carry frequency wc=50*pi %3 After DAC,we modulate the signal added cp.(dealing with the real part and imagine part of CT signal) wc=50*pi; TxSignalThenReal=real(TxSignalThen); %加CP后信号的实部 TxSignalThenRealcos= TxSignalThenReal.*cos(wc*t); %实部调制 TxSignalThenImag=im