m基于OFDM+QPSK和turbo编译码以及MMSE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
基于OFDM+QPSK和Turbo编码以及MMSE信道估计的无线图像传输是一种高效可靠的无线通信系统，广泛应用于图像传输领域。该系统利用正交频分复用（OFDM）技术，将图像数据分成多个子载波进行传输，利用QPSK调制进行信号调制，通过Turbo编码增强信号容错能力，并使用MMSE（最小均方误差）信道估计技术来减小信道传输误差。

3.MATLAB核心程序
``` for iii=1:length(datbin)/Iimage_len
[i,iii]
%%
%以单天线方式产生测试信号
%msg = rand(LenNc/4,1)>=0.5;
msg = [datbin(Iimage_len(iii-1)+1:Iimage_leniii)]';
%turbo编码
seridata1 = func_turbo_code(msg,N,M);
seridata = [seridata1,zeros(1,LenNc-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));

   %%
    %Step1：大规模MIMO信道
    [Hm,Hmmatrix]            = func_mychannels(Radius,Scale1,Scale2,Nh,Nv);       
    %Step2：多径参数和大规模MIMO参数输入到信道模型中
    %信道采样点数，每个调制符号采一个点
    [passchan_ofdm_symbol]   = func_conv_channels(Hmmatrix,Guard_int_ofdm_out,Nmultipath,Pow_avg,delay_multi,Fre_offset,timeval,iii);
    %Step3：噪声信道 
    Rec_ofdm_symbol          = awgn(passchan_ofdm_symbol,SNR_dB(i),'measured');

   %%
    %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
    %mmse
    [Sig_Lrmmse,Hs]  = func_mmse_est(fft_out,pilot_space,Pilot_seq,pilot_num,delay_avg/timeval,4e-6/timeval,10^(SNR_dB(i)/10));
    %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)]'];
end

```