OFDM MATLAB 通信系统仿真程序

%main_OFDM.m

%这是一个相对完整的 OFDM 通信系统的仿真设计，包括编码，调制，IFFT，

%上下变频，高斯信道建模，FFT，PAPR 抑制，各种同步，解调和解码等模

%块，并统括系统性能的仿真验证了系统设计的可靠性。

clear all

close all

clc

%++++++++++++++++++++++++++全局变量++++++++++++++++++++++++++++++

global seq_num

global count_dds_up

global count_dds_down

global count_dds_down_tmp

global dingshi

global m_syn

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

% SNR_Pre 设定用于仿真的信噪比的初值

% interval_SNR 设定用于仿真的信噪比间隔

% frame_num 每一个信噪比下仿真的数据帧数

interval_SNR=1;

for SNR_System=SNR_Pre:interval_SNR:5

frame_num=152;

dingshi=250;

err_int_final=0;

fwc_down=16.050;

fre_offset=0;

k0=1;

G=[1 0 1 1 0 1 1;1 1 1 1 0 0 1 ];

for seq_num=1:frame_num, %frame_num 帧数

datain=randint(1,90);

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

%++++++++++++++++++++++以下为信道卷积编码部分+++++++++++++++++++++

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

%+++++++++++++++++++++++++以下为 QPSK 调制部分+++++++++++++++++++++

QPSKdata=qpsk(interlacedata);

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

%+++++++++++++++++++++++++++生成训练序列+++++++++++++++++++++++++

if seq_num<3

trainsp_temp=seq_train();

end

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

PILOT=(1+j);

m_QPSKdata=QPSKdata;

data2fft_temp=[m_QPSKdata(1:8),PILOT,m_QPSKdata(9:16),PILOT,m_QPSKdata(17:24),PILO

T,m_QPSKdata(25:32),PILOT,m_QPSKdata(33:40),PILOT,m_QPSKdata(41:48),m_QPSKdata(4

OT,m_QPSKdata(81:88),PILOT,m_QPSKdata(89:end)];

trainsp_temp2=[trainsp_temp,zeros(1,128)];

trainsp=[trainsp_temp2(65:256),trainsp_temp2(1:64)];

matix_data=nyquistimp_PS();

matrix_mult=data2fft_temp*matix_data;

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

data2fft2=[matrix_mult(65:128),zeros(1,128),matrix_mult(1:64)];

%++++++++++++++++++++++++++++ifft 运算+++++++++++++++++++++++++++

elseif seq_num==2

ifftin=trainsp;

else

% plot(real(IFFTdata))

% figure

% plot(imag(IFFTdata))

% xlabel('imagIFFTdata')

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

%+++++++++++++++++++以下为插入循环前后缀，2 倍升采样+++++++++++++++

data2fir=add_CYC_upsample(IFFTdata,2);

% ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

% +++++++++++++++++++++++++fir 低通滤波++++++++++++++++++++++++++

guiyi_a=[0.0017216 0.010162 0.025512 0.028801 -0.0059219 -0.060115 -0.0496

0.091431 0.29636 0.3956 0.29636 0.091431 -0.0496 -0.060115 -0.0059219

0.028801 0.025512 0.010162 0.0017216 ];

txFIRdatai=filter(guiyi_a,1,real(data2fir));

txFIRdataq=filter(guiyi_a,1,imag(data2fir));

%+++++++++++++++++++++++++发射机 cic 滤波++++++++++++++++++++++++++

CICidatai=cic_inter(txFIRdatai,20);

CICidataq=cic_inter(txFIRdataq,20);

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

fwc_up=16; %控制字可以选择

DUCdata=up_convert_ofdm(fwc_up,CICidatai,CICidataq);

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

%++++++++++++++++++++++++++高斯白噪声信道++++++++++++++++++++++++

awgn_data=awgn(DUCdata,SNR_System);

%+++++++++++++++++++++++++++++下变频+++++++++++++++++++++++++++++

DUCdata_tmp=awgn_data;

CICddataq=cic_deci(DDCdataq,40,40);

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

%++++++++++++++++++++++++++++fir 低通滤波++++++++++++++++++++++++

guiyi_b=[ 0.019527-0.03934 0.049055 -0.018102 -0.1003 0.5944 0.5944 -0.1003 -

0.018102 0.049055 -0.03934 0.019527];

%抽样截止频率为 64kHZ,通带截止频率为 20kHZ，阻带截止频率为 30kHZ，带内纹波动小

rxFIRdatai=filter(guiyi_b,1,CICddatai);

rxFIRdataq=filter(guiyi_b,1,CICddataq);

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

q_rxFIRdatai=sign(rxFIRdatai);

q_rxFIRdataq=sign(rxFIRdataq);

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

if seq_num<3

end

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

fre_offset=fre_syn(rxFIRdatai,rxFIRdataq);

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

if seq_num>2

seq_num-2

rxFIRdata_syn=rxFIRdatai(fftw:fftw+255)+j*rxFIRdataq(fftw:fftw+255);

%++++++++++++++++++++++++++降 PAPR 逆矩阵变换++++++++++++++++++++++

fftdata_reg=[FFTdata(193:256),FFTdata(1:64)];

%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

% figure

% plot(rx_qpsk_din_th,'.')

% xlabel('星座图')

datatemp4=deqpsk(rx_qpsk_din_th);

datatemp4=sign(datatemp4);

for m=1:192

if datatemp4(m)==-1

datatemp4(m)=1;

elseif datatemp4(m)==1

datatemp4(m)=0;

end

end

%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

interdout=interlacedecode(datatemp4,8,24);

%++++++++++++++++++++以下为 viterbi 译码部分++++++++++++++++++++++

decodeDATA=viterbi(G,k0,interdout);

%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

err_final=sum(abs(decodeDATA-datain))

err_int_final=err_int_final+err_final

end

end

disp('------------------------------------------------------');