function demap_out = qam_demod(demap_int);
    global Mod_type Tx_num Ofdm_bits
    for t = 1:Tx_num-1
        tempt = dec2bin(demap_int(t,:),Mod_type);
        for n = 1:Ofdm_bits
            demap_out(t,(n-1)*Mod_type+1:n*Mod_type) = tempt(n,1:Mod_type)-48;     
        end
    end