LT码在高斯信道下的误码率仿真

Question

请给出LT码在高斯信道下的误码率随信噪比变化的曲线，译码用LLR-BP算法，编码的度分布就用经典的泊松度分布,k=512

Answer 1

K = 500;
m = K;
u = 0;
degree = 40; %迭代次數
sigema =sqrt(0.5); % %(0.5/r)10^(-0.1(Eb_N0));% Eb_N0 = 1 ; %单位：dB % n = 10;% r = m/n;%
P = [0.015 0.495 0.167 0.082 0.071 0.049 0.048 0.05 0.023];
P_du = [1 2 3 4 5 8 9 19 66];
sum = 0;
for i = 1:length(P) %将K换掉
sum = sum + P(i);
sum_1(i) = sum;
end
sum_1;
expense = [700,800,900,1000,1100,1200,1300];
run_freq_1 = 40;
tol_stats = zeros(7,run_freq_1);
tol_stats1 = zeros(7,run_freq_1);
for count_iii = 1:7
n = expense(count_iii);
for count_ii = 1:run_freq_1
Pgenerate = rand(1,n);
label = zeros(1,n);
for j_jj = 1:n
for i_ii = 1:10
if Pgenerate(j_jj)<=sum_1(i_ii)
label(j_jj)= P_du(i_ii);
break;
end
end
end
label;
for j = 1:n
a = zeros(1,m);
vector = randperm(m,label(j));
for i = 1:label(j)
a(vector(i)) = 1;
end
G(1:m,j) = a;
end
G;
x_1 = rand(1,m)<0.5;
y_1 = mod(x_1*G,2);
for i = 1:length(y_1)
if y_1(i) == 1
y_2(i) = -1;
else
y_2(i) = 1;
end
end
y_2;
y_22 = y_2 + sigema*randn(1,n)+u;
Lch = (2*y_22)/sigema/sigema;
LchLch = Lch;
for j = 1:n
for i = 1:m
if G(i,j)==1
Lch_1(j,i) = Lch(j);
end
end
end
for Loop = 1:degree
if Loop == 1
Lvc = zeros(m,n);
end
for j = 1:n
for i = 1:m
if G(i,j)==1
prod = 1;
for k = 1:m
if G(k,j)==1
if k=i
prod = prodtanh(0.5Lvc(k,j));
end
end
end
Lcv(j,i) = 2atanh((tanh(0.5Lch_1(j,i)))*prod);
else
Lcv(j,i) = 0;
end
end
end
for i = 1:m
for j = 1:n
if G(i,j)==1
sum_Lvc = 0;
for k = 1:n
if G(i,k)==1
if k=j
sum_Lvc=sum_Lvc+Lcv(k,i);
end
end
end
Lvc(i,j) = sum_Lvc;
else
Lvc(i,j) = 0;
end
end
end
end
for i = 1:m
sum = 0;
for j = 1:n
sum = sum + Lcv(j,i);
end
sum_judge(i) = sum;
end
for i = 1:m
if sum_judge(i)>0
sum_recode(i) = 0;
else
sum_recode(i) = 1;
end
end
sum_recode;
sum_error = 0;
for i = 1:m
if sum_recode(i)~=x_1(i)
sum_error = sum_error + 1;
end
end
ber = sum_error/m;
ber1(count_ii)=ber;
end
tol_stats(count_iii,1:run_freq_1) = ber1(1,1:run_freq_1);
end