lsb_error_pam.m

Hierarchical－QAM的程序

function [err_value] = lsb_error_pam(d_input_vector, snr)

% This function calculates the BER for the LSB.


m=length(d_input_vector);

%%%%% Calculate the actual coordinate vectors (x).

x=zeros(2^(m), 1);
d_0=zeros(2^(m-1), 1);
d_1=zeros(2^(m-1), 1);
B=zeros(2^(m-1), 1);

for i=2^(m-1):2^(m)-1
    index=i;
    mult=zeros(1,m);
    for j=m:-1:1
        mult(j)=2*mod(index,2)-1; % The 'for' loop generates b_{i,k} in (1)
        index=floor(index/2);
    end;
    x(i+1)=sum(mult .* d_input_vector); 
end;

for i=1:2^(m-1)
    x(i)=-x(2^(m)+1-i);
end;

%%% Generate d_0

d_0(1)=x(1);
d_0(2^(m-1))=x(2^m);
for i=2:2:2^(m-1)-1
	d_0(i)=x(2*i);
	d_0(i+1)=x(2*i+1);   %%% Note that x(2(i+1)-1)= x(2i+1)
end;

%%% Generate d_1 now

for i=1:2:2^(m-1)
	d_1(i)=x(2*i);
	d_1(i+1)=x(2*i+1);  %%% Again x(2(i+1)-1)=x(2i+1)
end;

%%% Now generate the B vector

for j=1:2^(m-1)
	B(j)=0.5*( x(2*j-1) + x(2*j) );
end;

B;
d_0;
d_1;

%%%%% Now B, d_0 and d_1 vectors are ready. Calculate the Error
err=0;
for i=1:1:2^(m-1)
    for j=1:2^(m-1)  
        err=err+((-1)^(j+1))*0.5*erfc((B(j,1)-d_0(i,1))/snr);
    end;
    err;
end;

for i=1:1:2^(m-1)
    for j=1:2^(m-1)
        err=err+ ((-1)^(j))*0.5*erfc((B(j,1)-d_1(i,1))/snr);
    end;
    err=err+1;
end;

err_value=err/(2^(m));