基于MATLAB的CDMA系统仿真姓名：班级：学号：指导老师：日期：作业要求1.分析附录的源程序，逐行给出中文注释，并分析仿真结果。
2.按照下列框图设计一个CDMA系统，并进行仿真。
1.分析附录的源程序，逐行给出中文注释，并分析仿真结果。
%main_IS95_forward.m%此函数用于IS-95前向链路系统的仿真，包括扩%频调制，匹配滤波，RAKE接收等相关通信模块。
%仿真环境: 加性高斯白噪声信道.%数据速率= 9600 KBps%clear allclose allclcdisp('--------------start-------------------');global Zi Zq Zs show R Gi Gqclear j;show = 0; %控制程序运行中的显示SD = 0; % 选择软/硬判决接收%-------------------主要的仿真参数设置------------------BitRate = 9600; %比特率ChipRate = 1228800; %码片速率N = 184; %源数据数MFType = 1; % 匹配滤波器类型--升余弦R = 5;%+++++++++++++++++++Viterbi生成多项式++++++++++++++++++G_Vit = [1 1 1 1 0 1 0 1 1; 1 0 1 1 1 0 0 0 1];%Viterbi生成多项式矩阵K = size(G_Vit, 2); %列数L = size(G_Vit, 1); %行数%++++++++++++++++++++++++++++++++++++++++++++++++++++++%++++++++++++++++++++++Walsh矩阵++++++++++++++++++++++++ WLen = 64; %walsh码的长度Walsh = reshape([1;0]*ones(1, WLen/2), WLen , 1); %32个1 0行%Walsh = zeros(WLen ,1);%++++++++++++++++++++++++++++++++++++++++++++++++++++++%++++++++++++++++++扩频调制PN码的生成多项式++++++++++++++%Gi = [ 1 0 1 0 0 0 1 1 1 0 1 0 0 0 0 1]';%Gq = [ 1 0 0 1 1 1 0 0 0 1 1 1 1 0 0 1]';Gi_ind = [15, 13, 9, 8, 7, 5, 0]'; %i路PN码生成多项式参数Gq_ind = [15, 12, 11, 10, 6, 5, 4, 3, 0]'; %q路PN码生成多项式参数Gi = zeros(16, 1); %16×1的0矩阵Gi(16-Gi_ind) = ones(size(Gi_ind));%根据Gi_ind配置i路PN码生成多项式Zi = [zeros(length(Gi)-1, 1); 1];% I路信道PN码生成器的初始状态Gq = zeros(16, 1); %16×1的0矩阵Gq(16-Gq_ind) = ones(size(Gq_ind)); %根据Gq_ind配置q路PN码生成多项式Zq = [zeros(length(Gq)-1, 1); 1];% Q路信道PN码生成器的初始状态%++++++++++++++++++++++++++++++++++++++++++++++++++++++%+++++++++++++++++++扰码生成多项式++++++++++++++++++++++Gs_ind = [42, 35, 33, 31, 27, 26, 25, 22, 21, 19, 18, 17, 16, 10, 7, 6, 5, 3, 2, 1, 0]'; Gs = zeros(43, 1); %43×1的0矩阵Gs(43-Gs_ind) = ones(size(Gs_ind)); %根据Gs_ind配置扰码生成多项式Zs = [zeros(length(Gs)-1, 1); 1];% 长序列生成器的初始状态%++++++++++++++++++++++++++++++++++++++++++++++++++++++%++++++++++++++++++++++AWGN信道++++++++++++++++++++++++ EbEc = 10*log10(ChipRate/BitRate);%处理增益EbEcVit = 10*log10(L);EbNo = [-2 : 0.5 : 6.5]; %仿真信噪比范围(dB)%EbNo = [-2 : 0.5 : -1.5];%++++++++++++++++++++++++++++++++++++++++++++++++++++++%------------------------------------------------------%-------------------------主程序-------------------------ErrorsB = []; ErrorsC = []; NN = [];if (SD == 1) % 判断软/硬判决接收fprintf('\n SOFT Decision Viterbi Decoder\n\n');elsefprintf('\n HARD Decision Viterbi Decoder\n\n');endfor i=1:length(EbNo) %根据EbNo多次运行fprintf('\nProcessing %1.1f (dB)', EbNo(i));%输出当前EbNo值iter = 0; ErrB = 0; ErrC = 0;while (ErrB <300) & (iter <150)drawnow;%++++++++++++++++++++++发射机+++++++++++++++++++++++TxData = (randn(N, 1)>0);%生成源数据% 速率为19.2Kcps[TxChips, Scrambler] = PacketBuilder(TxData, G_Vit, Gs); %产生IS-95前向链路系统的发送数据包% 速率为1.2288Mcps[x PN MF] = Modulator(TxChips, MFType, Walsh);%实现IS-95前向链路系统的数据调制%++++++++++++++++++++++++++++++++++++++++++++++++++++++%++++++++++++++++++++++++信道+++++++++++++++++++++++++++noise = 1/sqrt(2)*sqrt(R/2)*( randn(size(x)) + j*randn(size(x)))*10^(-(EbNo(i) - EbEc)/20);%生成噪声序列r = x+noise;%加入噪声%++++++++++++++++++++++++++++++++++++++++++++++++++++++%+++++++++++++++++++++++++接收机++++++++++++++++++++++++RxSD = Demodulator(r, PN, MF, Walsh); %软判决，速率为19.2 KcpsRxHD = (RxSD>0); % 定义接收码片的硬判决if (SD)[RxData Metric]= ReceiverSD(RxSD, G_Vit, Scrambler); %软判决else[RxData Metric]= ReceiverHD(RxHD, G_Vit, Scrambler); %硬判决end%++++++++++++++++++++++++++++++++++++++++++++++++++++++if(show)subplot(311); plot(RxSD, '-o'); title('Soft Decisions'); %软判决结果图subplot(312); plot(xor(TxChips, RxHD), '-o'); title('Chip Errors');%RAKE接收机输入符号与发送码相比出错的码subplot(313); plot(xor(TxData, RxData), '-o'); %硬判决接收机与发送数据相比的出错码title(['Data Bit Errors. Metric = ', num2str(Metric)]);pause;endif(mod(iter, 50)==0) %每50次保存一次fprintf('.');save TempResults ErrB ErrC N iter %保存结果endErrB = ErrB + sum(xor(RxData, TxData));%求出错比特数ErrC = ErrC + sum(xor(RxHD, TxChips)); %求出错码数iter = iter+ 1;%迭代次数endErrorsB = [ErrorsB; ErrB]; %存储各EbNo值下的出错比特数ErrorsC = [ErrorsC; ErrC]; %存储各EbNo值下的出错码数NN = [NN; N*iter]; %存储各EbNo值下的总数据码数目save SimData * %保存当前迭代的数据end%+++++++++++++++++++++++++误码率计算++++++++++++++++++++++++PerrB = ErrorsB./NN; %出错比特比例%PerrB1 = ErrorsB1./NN1;PerrC = ErrorsC./NN; %出错码比例Pbpsk= 1/2*erfc(sqrt(10.^(EbNo/10))); %EbNo的余误差PcVit= 1/2*erfc(sqrt(10.^((EbNo-EbEcVit)/10)));%EbNo-EbEcVit的余误差Pc = 1/2*erfc(sqrt(10.^((EbNo-EbEc)/10)));%EbNo-EbEc的余误差%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++%%+++++++++++++++++++++++++性能仿真显示++++++++++++++++++++++ figure;semilogy(EbNo(1:length(PerrB)), PerrB, 'b-*'); hold on;%信噪比误码率图% %semilogy(EbNo(1:length(PerrB1)), PerrB1, 'k-o'); hold on;% semilogy(EbNo(1:length(PerrC)), PerrC, 'b-o'); grid on;% semilogy(EbNo, Pbpsk, 'b-.^');% %semilogy(EbNo, PcVit, 'k-.x'); ylabel('BER');% semilogy(EbNo, Pc, 'b-.x');xlabel('信噪比/dB');ylabel('误码率');grid on;% legend('Pb of System (HD)', 'Pb of System (SD)', 'Pc before Viterbi of System',% ... 'Pb of BPSK with no Viterbi (theory)', 'Pc on Receiver (theory)');%% legend('Pb of System', 'Pc before Viterbi of System', ...%'Pb of BPSK with no Viterbi (theory)',%'Pc before Viterbi (theory)', 'Pc on Receiver (theory)');%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++disp('--------------end-------------------');%------------------------------------------------------% ************************beginning of file*****************************%PacketBuilder.mfunction [ChipsOut, Scrambler] = PacketBuilder(DataBits, G, Gs);%此函数用于产生IS-95前向链路系统的发送数据包%+++++++++++++++++++++++variables++++++++++++++++++++++++++++% DataBits 发送数据（二进制形式）% G Viterbi编码生成多项式% Gs 长序列生成多项式（扰码生成多项式）% ChipsOut 输入到调制器的码序列（二进制形式）% Scrambler 扰码%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ global Zs %扰码状态K = size(G, 2); %维特比多项式的长度L = size(G, 1); %每个数据比特的码片数N = 64*L*(length(DataBits)+K-1);% 码片数(9.6 Kbps -> 1.288 Mbps)chips = VitEnc(G, [DataBits; zeros(K-1,1)]); % Viterbi编码% 交织编码INTERL = reshape(chips, 24, 16); % IN：列, OUT：行chips = reshape(INTERL', length(chips), 1); %速率=19.2 KBps% 产生扰码[LongSeq Zs] = PNGen(Gs, Zs, N);%根据生成多项式和输入状态产生长度为N的PN序列Scrambler = LongSeq(1:64:end);%扰码ChipsOut = xor(chips, Scrambler); %加扰%************************end of file***********************************% ************************beginning of file*****************************%VitEnc.mfunction y = VitEnc(G, x);% 此函数根据生成多项式进行Viterbi编码%+++++++++++++++++++++++variables++++++++++++++++++++++++++++% G 生成多项式的矩阵% x 输入数据（二进制形式）% y Viterbi编码输出序列%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++K = size(G, 1); %每个数据比特的码片数L = length(x); %输入数据的长度yy = conv2(G, x'); %二维卷积yy = yy(:, 1:L); %根据L重新设定yy长度y = reshape(yy,K*L, 1);%矩阵变形y = mod(y, 2); %模二运算% ************************end of file*********************************** % ************************beginning of file***************************** %PNGen.mfunction [y, Z] = PNGen(G, Zin, N);%% 此函数是根据生成多项式和输入状态产生长度为N的伪随机序列%+++++++++++++++++++++++variables++++++++++++++++++++++++++++% G 生成多项式% Zin 移位寄存器初始化% N PN序列长度% y 生成的PN码序列% Z 移位寄存器的输出状态%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ L = length(G);%扰码生成多项式长度Z = Zin; % 移位寄存器的初始化y = zeros(N, 1);%N*1的0矩阵for i=1:Ny(i) = Z(L); %获取当前状态输出值（移位寄存器的最后一位输出）Z = xor(G*Z(L), Z); %生成移位寄存器次态Z = [Z(L); Z(1:L-1)]; %移位寄存器后移1位end%yy = filter(1, flipud(G), [1; zeros(N-1, 1)]);%yy = mod(yy, 2);%************************end of file*********************************** % ************************beginning of file***************************** %Modulator.mfunction [TxOut, PN, MF] = Modulator(chips, MFType, Walsh);%此函数用于实现IS-95前向链路系统的数据调制%+++++++++++++++++++++++variables++++++++++++++++++++++++++++% chips 发送的初始数据% MFType 成型滤波器的类型选择% Walsh walsh码% TxOut 调制输出信号序列% PN 用于扩频调制的PN码序列% MF 匹配滤波器参数%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ global Zi Zq show R Gi GqN = length(chips)*length(Walsh); %输出数据的数目% 输入速率= 19.2 KBps, 输出速率= 1.2288 Mcpstmp = sign(Walsh-1/2)*sign(chips'-1/2); %求扩频调制码数目的中间变量chips = reshape(tmp, prod(size(tmp)), 1);%矩阵变形[PNi Zi] = PNGen(Gi, Zi, N);%i路PN序列生成[PNq Zq] = PNGen(Gq, Zq, N);%q路PN序列生成PN = sign(PNi-1/2) + j*sign(PNq-1/2); %i、q路以复数形式合并chips_out = chips.*PN;%得到复数形式的码序列chips = [chips_out, zeros(N, R-1)];%码序列0插值chips = reshape(chips.' , N*R, 1);%矩阵变形%成型滤波器switch (MFType) %根据MFType选择滤波器类型case 1%升余弦滤波器L = 25;L_2 = floor(L/2);n = [-L_2:L_2]; %升余弦滤波器点数B = 0.7; %B越大拖尾越小MF = sinc(n/R).*(cos(pi*B*n/R)./(1-(2*B*n/R).^2)); %升余弦滤波器形状MF = MF/sqrt(sum(MF.^2)); %升余弦滤波器特性曲线case 2%矩形滤波器L = R;L_2 = floor(L/2);MF = ones(L, 1); %1->0,锐截止MF = MF/sqrt(sum(MF.^2)); %矩形滤波器特性曲线case 3%汉明滤波器L = R;L_2 = floor(L/2);MF = hamming(L);%生成汉明滤波器MF = MF/sqrt(sum(MF.^2));%汉明滤波器特性曲线endMF = MF(:); %转置TxOut = sqrt(R)*conv(MF, chips)/sqrt(2);%通过成型滤波器TxOut = TxOut(L_2+1: end - L_2); %限定序列区间if (show)figure;subplot(211); plot(MF, '-o'); title('Matched Filter'); grid on;%成型滤波器特性曲线图subplot(212); psd(TxOut, 1024, 1e3, 113); title('Spectrum'); %功率谱密度估计end% ************************end of file***********************************% ************************beginning of file*****************************%Demodulator.mfunction [SD] = Demodulator(RxIn, PN, MF, Walsh);% 此函数是实现基于RAKE接收机的IS-95前向信链路系统的数据包的解调%+++++++++++++++++++++++variables++++++++++++++++++++++++++++% RxIn 输入信号% PN PN码序列（用于解扩）% MF 匹配滤波器参数% Walsh 用于解调的walsh码% SD RAKE接收机的软判决输出%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++% DEMODULATOR This function performs demodulation of the forward% Channel packet, based on RAKE Receiver% Block Diagram% Input Signal -> [Matched Filter] -> [Sampler] -> [RAKE Receiver] -> [Walsh] -> [DeSpreading]% Inputs: RxIn - input signal (I/Q) analoge% PN - PN sequence (used for De-spreading)% MF - matched filter taps% Walsh - Used row of Walsh matrix for recovering %% Outputs: SD - Soft Decisions of RAKE receiver%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++global RN = length(RxIn)/R; %有用码的个数L = length(MF);L_2 = floor(L/2);rr = conv(flipud(conj(MF)), RxIn); %通过匹配接收滤波器rr = rr(L_2+1: end - L_2); %限定接收符号序列长度Rx = sign(real(rr(1:R:end))) + j*sign(imag(rr(1:R:end)));%接收符号采样Rx = reshape(Rx, 64, N/64); %列导向Walsh = ones(N/64, 1)*sign(Walsh'-1/2);%行导向walsh码PN = reshape(PN, 64, N/64)';%矩阵变形PN = PN.*Walsh;%walsh正交% 输入速率= 1.2288 Mpbs, 输出速率= 19.2 KBpsSD= PN*Rx;%解扩SD= real(diag(SD));%确定软判决输出% ***********************end of file***********************************% ************************beginning of file*****************************%ReceiverSD.mfunction [DataOut, Metric] = ReceiverSD(SDchips, G, Scrambler);% 此函数用于实现基于Viterbi译码的发送数据的恢复%+++++++++++++++++++++++variables++++++++++++++++++++++++++++% SDchips 软判决RAKE接收机输入符号% G Viterbi编码生成多项式矩阵% Scrambler 扰码序列% DataOut 接收数据（二进制形式）% Metric Viterbi译码最佳度量%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++if (nargin == 1)%判断只有SDchips传入时在此生成Viterbi编码生成多项式矩阵G = [1 1 1 1 0 1 0 1 1; 1 0 1 1 1 0 0 0 1];end% 速率=19.2 KBpsSDchips = SDchips.*sign(1/2-Scrambler);%解扰INTERL = reshape(SDchips, 16, 24);%解交织SDchips = reshape(INTERL', length(SDchips), 1); % 速率=19.2 KBps[DataOut Metric] = SoftVitDec(G, SDchips, 1);%实现软判决输入的Viterbi译码% ************************end of file**********************************% ************************beginning of file*****************************%SoftVitDec.mfunction [xx, BestMetric] = SoftVitDec(G, y, ZeroTail);%% 此函数是实现软判决输入的Viterbi译码%+++++++++++++++++++++++variables++++++++++++++++++++++++++++% G 生成多项式的矩阵% y 输入的待译码序列% ZeroTail 判断是否包含‘0’尾% xx Viterbi译码输出序列% BestMetric 最后的最佳度量%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++L = size(G, 1); % 输出码片数K= size(G, 2); % 生成多项式的长度N = 2^(K-1); % 状态数T = length(y)/L; % 最大栅格深度OutMtrx = zeros(N, 2*L); %输出矩阵的定义for s = 1:Nin0 = ones(L, 1)*[0, (dec2bin((s-1), (K-1))-'0')];in1 = ones(L, 1)*[1, (dec2bin((s-1), (K-1))-'0')];out0 = mod(sum((G.*in0)'), 2);out1 = mod(sum((G.*in1)'), 2);OutMtrx(s, :) = [out0, out1]; %生成输出矩阵endOutMtrx = sign(OutMtrx-1/2);PathMet = [100; zeros((N-1), 1)]; % 初始状态= 100PathMetTemp = PathMet(:,1); %副本Trellis = zeros(N, T); %栅格的矩阵Trellis(:,1) = [0 : (N-1)]';%给第一列赋值y = reshape(y, L, length(y)/L);%矩阵按输出码片数变形for t = 1:T %主栅格计算循环yy = y(:, t); %取出y的第t列for s = 0:N/2-1[B0 ind0] = max( PathMet(1+[2*s, 2*s+1]) + [OutMtrx(1+2*s, 0+[1:L]) * yy; OutMtrx(1+(2*s+1), 0+[1:L])*yy] );[B1 ind1] = max( PathMet(1+[2*s, 2*s+1]) + [OutMtrx(1+2*s, L+[1:L]) * yy; OutMtrx(1+(2*s+1), L+[1:L]) * yy] );PathMetTemp(1+[s, s+N/2]) = [B0; B1]; %改变状态Trellis(1+[s, s+N/2], t+1) = [2*s+(ind0-1); 2*s + (ind1-1)];%生成栅格矩阵endPathMet = PathMetTemp;%赋状态值endxx = zeros(T, 1);%生成单列0矩阵,输出变量if (ZeroTail) %确定最佳度量BestInd = 1;else[Mycop, BestInd] = max(PathMet); %非‘0’尾，取最大值所在位置endBestMetric = PathMet(BestInd); %得到最后的最佳度量xx(T) = floor((BestInd-1)/(N/2)); %赋值xx最后一个数NextState = Trellis(BestInd, (T+1)); %从栅格矩阵获得初态for t=T:-1:2xx(t-1) = floor(NextState/(N/2));%倒序生成xxNextState = Trellis( (NextState+1), t); %从栅格矩阵获得次态endif (ZeroTail)xx = xx(1:end-K+1);%限定译码输出序列长度end% ************************end of file***********************************% ************************beginning of file*****************************%ReceiverHD.mfunction [DataOut, Metric] = ReceiverHD(HDchips, G, Scrambler);% 此函数用于实现基于Viterbi译码的硬判决接收机%+++++++++++++++++++++++variables++++++++++++++++++++++++++++%HDchips 硬判决RAKE接收机输入符号% G Viterbi编码生成多项式矩阵% Scrambler 扰码序列% DataOut 接收数据（二进制形式）% Metric Viterbi译码最佳度量%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++if (nargin == 1) %判断只有HDchips传入时在此生成Viterbi编码生成多项式矩阵G = [1 1 1 1 0 1 0 1 1; 1 0 1 1 1 0 0 0 1];end% 速率=19.2 KBpsHDchips = xor(HDchips, Scrambler);%解扰INTERL = reshape(HDchips, 16, 24);%解交织HDchips = reshape(INTERL', length(HDchips), 1);%速率=19.2 KBps[DataOut Metric] = VitDec(G, HDchips, 1);%维特比解码%************************end of file***********************************% ************************beginning of file*****************************%VitDec.mfunction [xx, BestMetric] = VitDec(G, y, ZeroTail);%% 此函数是实现硬判决输入的Viterbi译码%+++++++++++++++++++++++variables++++++++++++++++++++++++++++% G 生成多项式的矩阵% y 输入的待译码序列% ZeroTail 判断是否包含‘0’尾% xx Viterbi译码输出序列% BestMetric 最后的最佳度量%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++L = size(G, 1); % 输出码片数K= size(G, 2); % 生成多项式长度N = 2^(K-1); % 状态数T = length(y)/L; % 最大栅格深度OutMtrx = zeros(N, 2*L);%输出矩阵的定义for s = 1:Nin0 = ones(L, 1)*[0, (dec2bin((s-1), (K-1))-'0')];in1 = ones(L, 1)*[1, (dec2bin((s-1), (K-1))-'0')];out0 = mod(sum((G.*in0)'), 2);out1 = mod(sum((G.*in1)'), 2);OutMtrx(s, :) = [out0, out1];%生成输出矩阵endPathMet = [0; 100*ones((N-1), 1)];%初始状态为0PathMetTemp = PathMet(:,1);%副本Trellis = zeros(N, T);%栅格的矩阵Trellis(:,1) = [0 : (N-1)]';%给第一列赋值y = reshape(y, L, length(y)/L);%矩阵按输出码片数变形for t = 1:T %主栅格计算循环yy = y(:, t)';%取出y的第t列for s = 0:N/2-1[B0 ind0] = min( PathMet(1+[2*s, 2*s+1]) + [sum(abs(OutMtrx(1+2*s, 0+[1:L]) - yy).^2); sum(abs(OutMtrx(1+(2*s+1), 0+[1:L]) - yy).^2)] );[B1 ind1] = min( PathMet(1+[2*s, 2*s+1]) + [sum(abs(OutMtrx(1+2*s, L+[1:L]) - yy).^2); sum(abs(OutMtrx(1+(2*s+1), L+[1:L]) - yy).^2)] );PathMetTemp(1+[s, s+N/2]) = [B0; B1];%改变状态Trellis(1+[s, s+N/2], t+1) = [2*s+(ind0-1); 2*s + (ind1-1)];%生成栅格矩阵endPathMet = PathMetTemp;%赋状态值endxx = zeros(T, 1);%生成单列0矩阵,输出变量if (ZeroTail) %确定最佳度量BestInd = 1;else[Mycop, BestInd] = min(PathMet);%非‘0’尾，取最小值所在位置endBestMetric = PathMet(BestInd);%得到最后的最佳度量xx(T) = floor((BestInd-1)/(N/2));%赋值xx最后一个数NextState = Trellis(BestInd, (T+1));%从栅格矩阵获得初态for t=T:-1:2xx(t-1) = floor(NextState/(N/2)); %倒序生成xxNextState = Trellis( (NextState+1), t);%从栅格矩阵获得次态endif (ZeroTail)xx = xx(1:end-K+1); %限定译码输出序列长度end% ************************end of file***********************************运行结果：图1 升余弦滤波器时的结果图2 矩形滤波器时代结果图3 矩形滤波器时代结果2.按照下列框图设计一个CDMA系统，并进行仿真。
