recurse_other.m

Hierarchical－QAM的程序

function [err_value] = recurse_other(position, d_input_vector, snr)

% This function recursively finds out the ber of bits in positions i_{1} 
% to i_{n-1}

m=length(d_input_vector);
d_output_vector1=zeros(1,m-1);
d_output_vector2=zeros(1,m-1);

if( m > 2) 
	if( position < m )
		alpha=d_input_vector(m-1)+d_input_vector(m);
		beta=d_input_vector(m-1)-d_input_vector(m);
    		for i=1:m-2
                        d_output_vector1(i)=d_input_vector(i);
		        d_output_vector2(i)=d_input_vector(i);
		end;               
       			d_output_vector1(m-1)=alpha;
			d_output_vector2(m-1)=beta;
d_output_vector1;
d_output_vector2;
position;
snr;

		err_value=0.5*recurse_other(position, d_output_vector1, snr)+0.5*recurse_other(position, d_output_vector2, snr);
	elseif(position == m);
		err_value=lsb_error_pam(d_input_vector, snr);
	end;
elseif( m==2 )
    if(position == 1)
	    err_value = 0.25*( erfc((d_input_vector(1)+d_input_vector(2))/snr ) + erfc((d_input_vector(1)-d_input_vector(2))/snr ) );
    elseif(position == 2)
        
err_value=0.5*erfc( (d_input_vector(2))/snr )-0.25*erfc( (2*d_input_vector(1)+d_input_vector(2))/snr )+ 0.25*erfc( (2*d_input_vector(1)-d_input_vector(2))/snr );
	end;  
end;