cdma.rar_CDMA通信_cdma_cdma matlab_interleaving cdma_通信系统发送

<matalb> CDMA信道仿真-AWGN多径衰落信道 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % % 该函数仿真CDMA系统的信道，在输入所需用户序列和其他干扰用户序列后 % % 在信号上叠加高斯白噪声，干扰用户多径干扰和所需用户的多径干扰和衰落。 % % 并根据输入延时曲线产生信道延时，输出mul_fad_sequence为信道信号输出 % % max_delay为信道最大延迟，fade_sign为瑞利信道中最大幅度分量的衰落量 % % mpath_amp为信道多径的幅度因子 % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% function [mul_fad_sequence,max_delay,fade_sign,rake_rev_sequence,mpath_amp] = cdma_channel_simulation(... sequence,sf,mpath_delay,eb_no,k_factor) % sequence 发射机的输出序列 % sf 扩频因子 % mpath_delay 多径传输延时 % snr 信道信噪比 % k_factor 莱斯k因子 mpath_delay = sort(mpath_delay); % 保证多径延时按照升序排列 eb_no_linear = 10^(eb_no/10); % 转换信号噪声比 [signal_row,signal_len] = size(sequence); if signal_row == 1 % 初始化干扰用户数目 interfering_num = 0; else interfering_num = signal_row - 1; end %% mpath_len = length(mpath_delay); % 多径成分，得到多径延迟曲线的长度 mpath_amp(2:mpath_len) = rand(1,mpath_len-1); % 随机生成多径成分幅度 scatter_power = mpath_amp*mpath_amp'; % 多径成分离散功率 mpath_amp(1) = sqrt(scatter_power*k_factor); % 视距成分的幅度(LOS) [max_mpath_amp,max_index] = max(mpath_amp); % 得到多径分量的最大幅度 mpath_amp = mpath_amp/max_mpath_amp; % 归一化多径衰落幅度，最大幅度因子为1 % 设计衰落信号的IIR滤波器 FilterOrder = 4; Ripple = 0.5; BW = 0.01; % 滤波器阶数为4，通带衰减为0.5，带宽0.01 [b,a] = cheby1(FilterOrder,Ripple,BW); % 得到切比雪夫1型滤波器的参数 %% %生成信道噪声 noise_amplitude = sqrt(sf/(2*eb_no_linear)); % 计算噪声的强度，如果扩频因子越大，信号对扩频序列的影响也越大 % 信道噪声与信噪比成反比，信噪比越大，噪声幅度越小 max_delay = max(mpath_delay); % 得到最大延时 len = signal_len; desired_noise = noise_amplitude*randn(1,len+max_delay); % 所需的噪声序列，长度要比信源序列的长度长最大延时单位 rake_desired_noise = desired_noise(1:len); %% mpath_len = length(mpath_delay); % 多径成分的向量长度 interfering_sequence = sequence(2:(interfering_num+1),:); if interfering_num > 0 % 如果存在干扰器 interfering_signal = zeros(interfering_num,len+max_delay); % 初始化干扰器的信号 rake_interfering_signal = zeros(mpath_len,len); for k = 1:mpath_len % 利用多径延时曲线成员的数量开始循环 rake_interfering_signal(k,:) = sum(mpath_amp(k)*... interfering_sequence,1); % 多径叠加，但消除延迟 index = 1+mpath_delay(k):len+mpath_delay(k); % 设置索引号 interfering_signal(:,index) = ... % 多径干扰信号采用加性叠加的方式 interfering_signal(:,index) + ... mpath_amp(k)*interfering_sequence; % mpath_amp相当于干扰码序列的权重因子 end end %% zf = zeros(FilterOrder,mpath_len); desired_sequence = sequence(1,:); desired_mpath_signal = zeros(1,len+max_delay); % 初始化所需的多径信号 rake_mpath_signal = zeros(mpath_len,len); for k = 1:mpath_len if k == 1 fading = ones(1,len); else fading = randn(1,len/(2^sf-1)) + k*randn(1,len/(2^sf-1)); % 信道模型，瑞利随机过程发生器 [fading zf(:,k)] = filter(b,a,fading,zf(:,k)); fading = interp(fading,(2^sf-1)); fading = abs(fading/sqrt(mean(fading.*conj(fading)))); end if k == max_index fade_sign = sign(fading); end rake_mpath_signal(k,:) = (mpath_amp(k)*fading).*desired_sequence; % rake不含延时的所需用户的多径衰落分量 index = 1+mpath_delay(k):len+mpath_delay(k); desired_mpath_signal(index) = ... % 利用瑞利随机过程发生器生成的随机衰落序列 desired_mpath_signal(index)+... % 产生衰减的效果 (mpath_amp(k)*fading).*desired_sequence; end %% if interfering_num > 0 % 合并用户多径信号，干扰用户多径信号和信道高斯白噪声 mul_fad_sequence = desired_mpath_signal + ... sum(interfering_signal,1) + desired_noise; for k = 1:mpath_len rake_rev_sequence(k,:) = rake_mpath_signal(k,:) + ... rake_interfering_signal(k,:) + rake_desired_noise; end else mul_fad_sequence = desired_mpath_signal + desired_noise; for k = 1:mpath_len rake_rev_sequence(k,:) = rake_mpath_signal(k,:) + rake_desired_noise; end end