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(2*Dqpsk(1:end-(Len*Nc-length(seridata1)))-1,N,M)]';
        %计算误码率
        %err_num          = Len*Nc/4-length(find(msg==Dqpsk_decode(1:Len*Nc/4)));
        %Error            = Error + err_num;
        Rimages = [Rimages,[Dqpsk_decode(1:Len*Nc/4)]'];