function error_ratio = err_static(demap_out,sig_code)
global Ofdm_bits Mod_type Tx_num
sig_all_num = Ofdm_bits*Mod_type*Tx_num;
error_ratio = 0;
error_num = 0;
error_matrix = zeros(Tx_num,Ofdm_bits*Mod_type);
for t = 1:Tx_num 
    for n = 1:Ofdm_bits*Mod_type   
        if demap_out(t,n)~=sig_code(t,n)
            error_num = error_num+1;
            error_matrix(t,n) = 1;
        end
    end
end
error_ratio = error_num/sig_all_num;