matlab卷积码程序

1、1、卷积码编码functionoutput=cnv_encd(input)%output=cnv_encd(g,k0,input)卷积码编码函数%g生成矩阵%k0输入码长%input输入信源序列%output输出卷积编码序列g=111;101;编码矩阵k0=1;input=1101;ifrem(length(input),k0)>0input=input,zeros(size(1:k0-rem(length(input),k0);endn=length(input)/k0;ifrem(size(g,2),k0)>0error('Error,gisnotoftherights

2、ize.')endli=size(g,2)/k0;n0=size(g,1);u=zeros(size(1:(li-1)*k0),input,zeros(size(1:(li-1)*k0);u1=u(li*k0:-1:1);fori=1:n+li-2u1=u1,u(i+li)*k0:-1:i*k0+1);enduu=reshape(u1,li*k0,n+li-1);output=reshape(rem(g*uu,2),1,n0*(n+li-1);2、Viterbi译码程序1)functiony=bin2deci(x)l=length(x);y=(l-1:-1:0);y=2.Ay;y=x*

3、y'2)functiony=deci2bin(x,l)y=zeros(1,l);i=1;whilex>=0&i<=ly(i尸rem(x,2);x=(x-y(i)/2;i=i+1;endy=y(l:-1:1);3)functiondistance=metric(x,y)ifx=ydistance=0;elsedistance=1;end4)functionnext_state,memory_contents=nxt_stat(current_state,input,L,k)binary_state=deci2bin(current_state,k*(L-1);bina

4、ry_input=deci2bin(input,k);next_state_binary=binary_input,binary_state(1:(L-2)*k);next_state=bin2deci(next_state_binary);memory_contents=binary_input,binary_state;5)functiondecoder_output,survivor_state,cumulated_metric=viterbi(channel,snr_db)G=111;101;%G卷积编码矩阵，如(2,1,3)卷积码生成矩阵111;101,可以根据自己的需要输入编码矩阵

5、k=1;%k信息源输入端口数k=1channel=110101001011;%信源编码snr_db=6;%信噪比，可以通过调节信噪比大小观察viterbi译码的性能%bpsk调制channel_output=bpsk(channel,snr_db);%调用bpsk函数，得到信道编码n=size(G,1);%n编码输出端口数量，(2,1,3)中n=2ifrem(size(G,2),k)=0%当G列数不是k的整数倍时error('SizeofGandkdonotagree')%发出出错信息endifrem(size(channel_output,2),n)=0%当输出量元素个数不是

6、输出端口的整数倍时error('channeloutputnotoftherightsize')endN=size(G,2)/k;%得出移位数，即寄存器的个数M=2Ak;number_of_states=2A(k*(N-1);%状态数forj=0:number_of_states-1%j表示当前寄存器组的状态因为状态是从零%开始的，所以循环从0到number_of_states-1form=0:M-1%m为从k个输入端的信号组成的状态，总的状%态数为2Ak,所以循环从0到2Ak-1%nxt_stat完成从当前的状态和输入的矢量得出下寄存器组的一个状态next_state,mem

7、ory_contents=nxt_stat(j,m,N,k);%调用nxt_stat函数input(j+1,next_state+1)=m;branch_output=rem(memory_contents*G',2);nextstate(j+1,m+1)=next_state;output(j+1,m+1)=bin2deci(branch_output);endend%state_metric数组用于记录译码过程在每状态时的汉明距离%state_metric大小为number_of_states2,(:,1)当前%状态位置的汉明距离，为确定值，而(：,2)为当前状态加输入%得到的下一

8、个状态汉明距离，为临时值state_metric=zeros(number_of_states,2);depth_of_trellis=length(channel_output)/n;channel_output_matrix=reshape(channel_output,n,depth_of_trellis);survivor_state=zeros(number_of_states,depth_of_trellis+1);fori=1:depth_of_trellis-N+1flag=zeros(1,number_of_states);if(i<=N)step=2A(k*(N-i)

9、;elsestep=1;endforj=0:step:number_of_states-1form=0:M-1branch_metric=0;binary_output=deci2bin(output(j+1,m+1),n);forll=1:nbranch_metric=branch_metric+metric(channel_output_matrix(ll,i),binary_output(ll);end%选择码间距离较小的那条路径%选择方法：%当下一个状态没有被访问时就直接赋值，否则，用比它小的将其覆盖if(state_metric(nextstate(j+1,m+1)+1,2)>

10、state_metric(j+1,1)+branch_metric)|flag(nextstate(j+1,m+1)+1)=0)state_metric(nextstate(j+1,m+1)+1,2)=state_metric(j+1,1)+branch_metric;survivor_state(nextstate(j+1,m+1)+1,i+1)=j;flag(nextstate(j+1,m+1)+1)=1;endendendstate_metric=state_metric(:,2:-1:1);endfori=depth_of_trellis-N+2:depth_of_trellisfla

11、g=zeros(1,number_of_states);%状态数从number_of_statesfnumber_of_states/2f.f2f1%程序说明同上，只不过输入矢量只为0last_stop=number_of_states/(2A(k*(i-depth_of_trellis+N-2);forj=0:last_stop-1branch_metric=0;binary_output=deci2bin(output(j+1,1),n);forll=1:nbranch_metric=branch_metric+metric(channel_output_matrix(ll,i),bina

12、ry_output(ll);endif(state_metric(nextstate(j+1,1)+1,2)>state_metric(j+1,1)+branch_metric)|flag(nextstate(j+1,1)+1)=0)state_metric(nextstate(j+1,1)+1,2)=state_metric(j+1,1)+branch_metric;survivor_state(nextstate(j+1,1)+1,i+1)=j;flag(nextstate(j+1,1)+1)=1;endendstate_metric=state_metric(:,2:-1:1);e

13、nd%从最佳路径中产生解码%译码过程可从数组survivor_state的最后一个位置向前逐级译码state_sequence=zeros(1,depth_of_trellis+1);state_sequence(1,depth_of_trellis尸survivor_state(1,depth_of_trellis+1);fori=1:depth_of_trellisstate_sequence(1,depth_of_trellis-i+1)=survivor_state(state_sequence(1,depth_of_trellis+2-i)+1),depth_of_trellis-i

14、+2);enddecoder_output_matrix=zeros(k,depth_of_trellis-N+1);fori=1:depth_of_trellis-N+1%根据数组input的定义来得出从当前状态到下一个状态的输入信号矢量dec_output_deci=input(state_sequence(1,i)+1,state_sequence(1,i+1)+1);dec_output_bin=deci2bin(dec_output_deci,k);%将一次译码存入译码输出矩阵decoder_output_matrix相应的位置decoder_output_matrix(:,i尸de

15、c_output_bin(k:-1:1)'enddecoder_output=reshape(decoder_output_matrix,1,k*(depth_of_trellis-N+1);cumulated_metric=state_metric(1,1);3、卷积码译码误码性能分析clearall;clc;cycl=50;snr_db=0:1:10;%输入信息msg=randint(1,1024);ber0=zeros(cycl,length(snr_db);berl=zeros(cycl,length(snr_db);ber2=zeros(cycl,length(snr_db)

16、;%Trellisestrel=poly2trellis(3,57);%Definetrellisforrate1/2code.forn=1:cyclforx=1:length(snr_db)%Codewordscode=convenc(msg,trel);%Encode.%Interleaverstate=20;inter=randintrlv(code,state);%BPSK调制s0=sign(msg-0.5);si=sign(inter-0.5);s2=sign(code-0.5);%AWGNChanneladd_noise0=awgn(s0,snr_db(x),'measur

17、ed');add_noise1=awgn(s1,snr_db(x),'measured');add_noise2=awgn(s2,snr_db(x),'measured');%Deinterleaverwithnoiseforsoftdecodingdeinter_noise=randdeintrlv(add_noise1,state);%解调r_0=0.5*sign(add_noise0)+0.5;r_1=0.5*sign(add_noise1)+0.5;r_2=0.5*sign(add_noise2)+0.5;%Deinterleaverdeinte

18、r_1=randdeintrlv(r_1,state);%Tracebacklengthtblen=5;%vitdec硬判决decodedi=vitdec(deinter_1,trel,tblen,'cont','hard');%vitdec软判决y,qcode=quantiz(deinter_noise,-.75-.5-.250.25.5.75,7:-1:0);decoded2=vitdec(qcode,trel,tblen,'cont','soft',3);%比较误码率num0,rat0=biterr(r_0,msg);num1,rat1=biterr(double(decoded1(tblen+1:end),msg(1:end-tblen);num2,rat2=biterr(double(decoded2(tblen+1:end),msg(1:end-tblen);ber0(n,x)=rat0;ber1(n,x)=rati;ber2(n,x)=rat2;endendber0=mean(ber0)