m基于OFDM+QPSK和turbo编译码以及LS信道估计的无线图像传输matlab仿真

1.算法仿真效果

matlab2022a仿真结果如下：

 

2.算法涉及理论知识概要

       正交频分复用（OFDM）技术将图像数据分成多个子载波进行传输，使用QPSK调制对信号进行调制，通过Turbo编码增强信号的纠错能力，并采用LS信道估计技术来估计信道状态。

 

系统原理：

 

 

3.MATLAB核心程序 `%以单天线方式产生测试信号

        %msg                            = rand(Len*Nc/4,1)>=0.5;

        msg                            = [datbin(Iimage_len*(iii-1)+1:Iimage_len*iii)]';

        %turbo编码

        seridata1                      = func_turbo_code(msg,N,M);

        seridata                       = [seridata1,zeros(1,Len*Nc-length(seridata1))]';

        %QPSK映射

        [Qpsk0,Dqpsk_pilot,symbol_bit] = func_piQPSK_mod(seridata);

        %变换为矩阵   

        Qpsk_matrix                    = reshape(Qpsk0,fftlen,Nc);

        [Pilot_in,pilot_num,Pilot_seq,pilot_space] = func_insert_pilot(Dqpsk_pilot,Qpsk_matrix,pilot_type,T,TG);

        Pilot_in                       = fft(Pilot_in);

        %sub carrier mapping

        Pilot_in                       = func_subcarrierMap(Pilot_in);

        %IFFT transform，产生OFDM信号

        ifft_out                       = ifft(Pilot_in);

        %插入包含间隔     

        Guard_int                      = ceil(BWs/fftlen);  

        Guard_int_ofdm                 = func_guard_interval_insert(ifft_out,fftlen,Guard_int);

        %将矩阵数据转换为串行进行输出

        Guard_int_ofdm_out             = reshape(Guard_int_ofdm,1,(fftlen+Guard_int)*(Nc+pilot_num));

        

............................................................................

       %%

        %开始接收

        Guard_int_remove = func_guard_interval_remove(Rec_ofdm_symbol,(fftlen+Guard_int),Guard_int,(Nc+pilot_num));

        %FFT

        fft_out          = fft(Guard_int_remove);

        %sub carrier demapping

        fft_out          = func_desubcarrierMap(fft_out);

        fft_out          = ifft(fft_out);

        %信道估计

        %ls

        [Sig_Lrmmse,Hs]  = func_ls_estimation(fft_out,pilot_space,Pilot_seq,pilot_num);

        %解调

        Dqpsk            = func_pideMapping(Sig_Lrmmse,fftlen*Nc);

        %turbo解码

        Dqpsk_decode     = [func_turbo_decode(2Dqpsk(1:end-(LenNc-length(seridata1)))-1,N,M)]';

        %计算误码率

        %err_num          = LenNc/4-length(find(msg==Dqpsk_decode(1:LenNc/4)));

        %Error            = Error + err_num;

        Rimages = [Rimages,[Dqpsk_decode(1:Len*Nc/4)]'];`